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Procedia - Social and Behavioral Sciences 68 (2012) 87 – 98

AicE-Bs 2012 Cairo ASIA Pacific International Conference on Environment-Behaviour Studies Mercure Le Sphinx Cairo Hotel, Giza, Egypt, 31 October

2 November 2012

-Cultural and

Lean Construction: Towards enhancing sustainable construction in Malaysia Mohd Arif Marhani*, Aini Jaapar, Nor Azmi Ahmad Bari Faculty of Architecture, Planning and Surveying, Universiti Teknologi MARA, Shah Alam 40450, Malaysia

Abstract Lean Construction (LC) is aimed at reducing waste, increasing productivity and health and safety in fulfilling the of the construction industry. This paper provided the fundamental knowledge of LC and highlighted its implementation in the construction industry. It was discovered that the knowledge of stakeholders are reasonably significant as the principles of LC is widely implemented in the work field. However, the stakeholders are indifferent in their understanding on the basic terminologies of LC hence unable to reap its full potential. It was proven that by implementing LC, the construction industry benefits by maximising value and improved sustainability. © Authors. by Elsevier Ltd.and Open access under CC BY-NC-ND license. © 2012 2012 The Published byPublished Elsevier Ltd. Selection peer-review under responsibility of the Centre for EnvironmentSelection and peer-review under responsibility of the Centre for Environment-Behaviour Studies (cE-Bs), of Behaviour Studies (cE-Bs), Faculty of Architecture, Planning and Surveying, Universiti Teknologi MARA,Faculty Malaysia. Architecture, Planning & Surveying, Universiti Teknologi MARA, Malaysia. Keywords: Lean construction; health and safety; sustainable construction; Malaysian construction industry

1. Introduction Egan (1998) proposed the United Kingdom construction industry to improve its capabilities and efficiency in modernising the industry and increasing user satisfaction. As a result of the statement, LC is a way forward to design production systems in minimising waste of materials, time and effort which leads to possible generation of maximum amount of value. Koskela and Howell (2002), insisted that the various parties involved in the industry such as the construction firms, non-profit organisations, and overseeing administrative bodies to have greater efforts towards sustainability and greener environment for better sustainable construction leading to the better future of the country.The Construction Industry Master Plan 2006-2015 (CIMP, 2006) highlighted one of the challenges facing by the Malaysian

* Corresponding author. Tel.: +6-03-55444376; fax: +6-03-55444353. E-mail address: [email protected].

1877-0428 © 2012 The Authors. Published by Elsevier Ltd. Open access under CC BY-NC-ND license.

Selection and peer-review under responsibility of the Centre for Environment-Behaviour Studies (cE-Bs), Faculty of Architecture, Planning & Surveying, Universiti Teknologi MARA, Malaysia. doi:10.1016/j.sbspro.2012.12.209

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construction industry is the availability of cheap foreign labour which encourages labour intensive construction methods over the use of more innovative methods. This hampers increase productivity and quality in the long run. Accordingly, the CIMP has recommended the industry to extend the use of modern construction methods and information technology. Specifically, the use of Industialised Building System (IBS) related systems may help to ease the pressures of labour requirements whilst boosting quality and productivity. The wider adoption of IBS is also encouraged as a means to overcome environmental issues associated with conventional methods. From the reviews of the literatures, LC is able to overcome the challenges highlighted previously. Womack and Jones (1996) suggested that lean production is able to reduce the overall cost especially the indirect cost while still maintaining the quality standards and reducing manufacturing cycle time. Ballard and Howell (1998) added that LC is different from other construction management due to its clear set of objectives. Its aimed for the delivery process, concurrent product design and process, and production control throughout the life of the project. Black (2008) stated that LC extends from the objectives of a lean production system, which are maximising value and minimising waste; to specific techniques and applies them in a new project delivery process. Having said that, Lim (2008) concluded that the Malaysian construction level of knowledge on LC were high. However, they are unable to fully understand the terminology of LC even though its principles is applied in their work field. This scenario was proven from the preliminary investigation done earlier on tw sation. LC principles are claimed being applied in the construction process, yet the technical methodology of LC was not fully utilised in the production process. The main objective of this paper is to provide a basis of fundamental knowledge and understanding on LC for Malaysia construction stakeholders. An extensive literature review was conducted in order to achieve the objectives of this paper. This paper is also aimed at highlighting on how to incorporate the LC concept in the construction industry to promote sustainable construction. 2. The Historical of Lean Construction Basically, LC is a big scale of adaptation from the Japanese manufacturing principles and the concept is implemented to the construction process (Bertelsen, 2004). Cullen et al. (2005) stated that the principles of LC, which arose from adapting the concepts of lean production had been developed by leadership of Taiichi Ohno. Starting from efforts to reduce machine set up time and influenced by total quality management, he developed a simple set of objectives for the design of the production system, which is to produce a car to the requirements of a specific customer, deliver it instantly, and maintain no inventories or intermediate stores (Lim, 2008). Lean production methods have been applied in the Japanese car industry as a key to success from According to Murman et al. (2002), lean production or manufacturing concept comprises a variety of production systems that share certain principles, including waste minimisation, responsiveness to change, just-in-time, effective relationships within the value stream, continuous improvement, and quality from the beginning. This concept continues to evolve but the basic outline is clear, which designs a production system that will deliver a custom product instantly in order but maintain no intermediate inventories (Howell, 1999).

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3. The Evolution of Lean Construction 3.1. Global evolution LC has been introduced as a new management approach to the construction industry by Koskela and Howell (2002). It is hoped the successful adaptation of this concept will not only be beneficial to the clients but also to the communities and environment itself. According to Howell (1999), there were many barriers in implementing lean concepts in the construction fields. This point of view is affirmed by Senaratne and Wijesiri (2008), which stated that if a company successfully implements the concept of LC, it would be able to gain significant cost advantage by eliminating cost-consuming flow activities and become a cost leader. Furthermore, based on Johansen and Walter (2007), construction industries all over the world such as Australia, Brazil, Denmark, Ecuador, Finland, Peru, Singapore, United Kingdom, United States of America and Venezuela have implemented the lean concepts within the industry and have reaped its benefits. Moreover, according to Salem et al. (2005) the LC approach is different from the normal practices as LC is based on production management principles and it gained better results in complex, uncertain and quick projects. In addition, Jorgensen and Emmitt (2008) said common elements as tself have expressively shown focus on specific aspects which are proven to be capable of bringing benefits. 3.2. The current evolution of lean construction in Malaysia needs without compromising the opportunity and ability for future generation needs (WCED, 1987). In materialising this effort, the construction industry is urged to move from traditional, labour consuming, energy inefficient and waste generated method of construction to more environmentally friendly, energy efficient and less waste generation of the construction environment. Pratt (2000) stated that Malaysian projects in the last decade, especially the magnificent monuments were not cost and function effective. On certain construction projects, the budgets were overstepped, longer construction period and quality of the end products were poor (Ibrahim et al., 2010). Furthermore, due to health and safety issues, according to the statistics reported by the Social Security Organisation (SOCSO) the numbers of fatality cases in the construction industry are among the highest in the 10 categorised industries in Malaysia (SOCSO 2004). The fatality rate of cases in the Malaysia construction industry was more than 3 times of other workplace with 3.3% as compared to 1.1% for other workplaces such as manufacturing and mining and quarrying (SOCSO, 2000). In Malaysia other than Lim (2008), among other pioneer researches on LC was conducted by Abdullah et al. (2009). The study concluded that the application of LC is limited due to the nature of the construction industry, which is very unique, high risks and one-off. Lim (2008) added earlier that its knowledge has been widely accepted by the stakeholders. From the literature research, it was indicated that there is a need for more holistic approaches such as incorporating the other important aspects to the LC key concepts towards sustainable and better future environment. According to Bashir et al. (2011), health and safety has been considered in the implementation of lean principles. Through proper health and safety assessment implemented on construction project, it will assist a construction company in dealing and assuring their health and safety risks and improving their performance e.g. Occupational Health and Safety Assessment Series (OHSAS) 18001. By implementing OHSAS 18001, which is for health and safety management systems, it will provide improvement in worker safety consciousness and morale,

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reductions in accidents, claims and lost work days, and better prepare for regulatory inspections (National Quality Assurance USA, 2012). 4. Definitions and Concept of Lean Construction 4.1. The Definitions From the literature reviews conducted, many definitions of LC have been discovered indicating the positive evolution of lean methodology as well as its diversity. The definitions stated below would best describe the methodology and application of LC:Koskela (1992) Advantages of the new production philosophy in terms of productivity, quality, and indicators were solid enough in practice in order to enhance the rapid diffusion of the new principles Howell (1999) Lean construction is much like the current practice as the goal of better meeting customer needs while using less of everything Lukowski (2010) Lean construction is the practical application of lean manufacturing principles, or lean thinking, to the building environment Yahya and Mohamad (2011) Lean construction is about managing and improving the construction process to profitability deliver what the customer needs by eliminating waste in the construction flow by using the right principle, resources and measure to deliver things right first time The first definition can be considered a concise definition of LC which acknowledges the key essentials of LC. The second and third definition by Howell (1999) and Lukowski (2010) reflected the first definition, as well as it provides a linkage between them. The fourth definition by Malaysian researchers (Yahya and Mohamad, 2011) emphasised on the key features of LC which is eliminating construction waste. The evolution of the LC definitions is elaborated further by the Lean Construction is a production management-based approach to project delivery - a new way to design and build capital facilities. Lean production management has caused a revolution in manufacturing design, supply and assembly. LC extends from the objectives of a lean production system maximise value and minimise waste - to specific techniques and applies them in a new project delivery A in Malaysia would be: LC is a concurrent and continuous improvement to the construction project by reducing waste of resources and at the same time able to increase productivity and secure a better health and safety greener environment. 4.2. The concept of lean construction The core concept behind lean production is to enable the flow of value creating work steps while eliminating non-value steps e.g. waste by focusing on fast cycle times. When waste is removed from the production process, cycle times drop until physical limits are reached. Value-adding activities are however, first improved through internal continuous improvement and fine-tuning of existing machinery. Only after these improvement potentials are realised, major involvements in new technology are

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Japanese term for the activity that is to avoid waste of time, money, equipment etc. (Shingo, 1992). LC accepts Ohno's production system design criteria (Cullen et al., 2005) as a standard of perfection (Howell, 1999). Waste is defined by the performance criteria for the production system and failure to oskela, 1992). Waste in construction and manufacturing arises from the same activity centered thinking. However, Howell (1999), argues that there is a need to maintain pressure on every activity to ensure continuous improvement through the reduction of cost and duration of each activity. Lean theory, principles and techniques, taken together, provide the foundation for a new form of project management. LC recommends the simultaneous consideration of product and process development. According to Howell (1999), managing construction under lean is different from typical contemporary practice because it has a clear set of objectives in the delivery process, which is aimed at maximising the performance for the end user at the project level. By implementing the lean concept, production control should be done throughout the life of the project. Walter and Johansen (2007) described the application of the lean concept in the construction industry was still restricted and sluggish. In addition, many ideas from manufacturing have been rejected by the stakeholders because of the belief that both industries were not alike (Howell, 1999). The uniqueness of the construction project with deficiency of repetition and doubt in the environment (Koskela, 1992) under great time and schedule pressure was fundamentally in contrast to manufacturing industry (Ballard and Howell, 1998). From the discussion, the authors highly suggested LC concept to be applied extensively in order to manage and enhance the process of construction not only to cater with the client s need but beneficial to the environment and communities. This is in accordance to Howell (1999), which emphasised continuous improvement should be carried concurrently in the construction process and the participation of all stakeholders will influence whether a construction project is successful or not in implementing the concept. 5. The Lean Construction Principles From the literature research, in order to implement the LC, Koskela (1992) identified eleven LC principles to be implemented to the total flow process and its sub process in the construction industry (see Table 1). The principles are to reduce the share of non value-adding activities, increase output value through systematic consideration of customer requirements, reduce variability, reduce cycle time, minimise the number of steps, parts and linkages, increase output flexibility, increase process transparency, focus control on the complete process, build continuous improvement into the process, balance flow improvement with conversion improvement and benchmarking. On the other hand, Womack and Jones (1996) discovered there were five principles of lean construction, which are specify value-creating flow, achieving customer pull at the right time and pursue perfection for continuous improvement. In addition, Lim (2008), Lean Enterprise Institute (2009) and Bashir et al. (2011) have the same point of view with Womack and Jones, but Lean Enterprise Institute used different keywords: (see Fig. 1). Meanwhile, Cain (2004) described six principles of construction best practice on LC (see Table 2). The principles are delighted end users, end users benefitting from the lowest optimum cost of ownership, elimination of inefficiency and waste in the use of labour and materials, the involvement of specialist suppliers to achieve integration and buildability, a single point of contact for the most effective coordination and clarity of responsibility and establishment of current performance and improvement

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achievements by measurement. On the other hand, Salem and Zimmer (2005) suggested the five lean principles that applicable in the construction industry are customer focus, culture/people, workplaces standardisation, waste elimination and continuous improvement/built-in quality. Table 1. Lean construction principles Authors

LC Principles

Koskela (1992)

Reduce non value-adding activities Increase output value Reduce variability Reduce cycle time Minimise the number of steps, parts and linkages Increase output flexibility Increase process transparency Focus control on the complete process Build continuous improvement into the process Balance flow improvement with conversion improvement Benchmarking

Womack and Jones (1996), Lim (2008) and Bashir et al. (2011)

Specify value Identify the value stream Flow Pull Pursue perfection

Lean Enterprise Institute (2009)

Identify value Map the value stream Create flow Establish pull Seek perfection

Table 2. Lean construction principles in construction Authors Cain (2004)

1. 2. 3. 4. 5. 6.

Salem and Zimmer (2005)

1. 2. 3. 4. 5.

LC Principles in Construction Delighted end users End users benefitting from the lowest optimum cost Elimination of inefficiency and waste The involvement of suppliers to achieve integration and buildability A single point of contact for the most effective coordination and clarity of responsibility Establishment of current performance and improvement achievements by measurement Customer focus Culture/people Workplaces standardisation Waste elimination Continuous improvement/built-in quality

Mohd Arif Marhani et al. / Procedia - Social and Behavioral Sciences 68 (2012) 87 – 98

1. Identify value 2. Map the value stream

5. Seek perfection

3. Create flow

4. Establish

Fig. 1. Lean construction principles. source: lean enterprise institute (2009)

From the discussion, the authors agree with Womack and Jones (1996), Lim (2008), Lean Enterprise Institute (2009) and Bashir et al. (2011) on the five principles of LC but believe that LC as stated by Koskela (1992) should be focused on value rather than on cost only and as well as seeks to remove all non-value adding components and processes. Lean principles can only be applied fully and effectively in the construction industry by focusing on improving the whole process, integration among the stakeholders of a project and increase transparency especially on health and safety issues. With continuous improvement (Japanese: Kaizen) done and with waste eliminated along the flow process, perfection is the ultimate sweet reward that companies can achieve (Womack and Jones, 1996). 6. Incorporating Lean Construction in Construction Process It is important for the stakeholders to incorporate LC in the construction process. Koskela (1992) expressed lots of benefits when implementing LC in construction projects. The greater benefit is construction companies can reduce the construction cost by using precise materials and fewer waste. In addition, by having a proper strategic planning, the construction period will be shortened. There were many of key concepts of LC that can be implemented by the stakeholders. Alinaitwe (2009) described the concepts included Just-In-Time (JIT), Total Quality Management (TQM), Business Process Reengineering (BPR), Concurrent Engineering (CE) and Last Planner System (LPS); Teamwork and Value Based Management (VBM) (Harris and McCaffer, 1997); and OHSAS 18001. The authors believe that most of these concepts are interconnected and it is important to understand all the key concepts of LC, which may improve performance while minimising construction waste. (see Table 3) The authors suggest OHSAS 18001 as one of the key concept of LC that can be implemented in the construction process. OHSAS 18001 is a series of Occupation Health and Safety Assessment Series for health and safety management systems, which is intended to help a construction company to manage their occupational health and safety risks (OHSAS 18001, 2012). Although OHSAS 18001 is not a legal requirement, it is proven and internationally recognised. In addition, OHSAS 18001 is a combination of the management organisational systems that can improve health and safety performance by having planning and review, the consultative arrangements and the specific program elements (Biggs et al., 2005).

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Table 3. Key concepts of lean construction Key concepts

Essential Factors

Authors

Just-In-Time (JIT)

Three methods linked with JIT: optimise inventories according to backward requests (Japanese: Kanban), construction leveling and decreasing the number of setup activities.

Salem et al. (2006)

Related to the waste concept.

Koskela (1992)

Continuous improvement of procedures, equipment and processes in order to eliminate waste. Total Quality Management (TQM)

As an integrated management thinking and actions encouraged an organisation-wide focus on quality.

Small et al. (2011)

An quality of goods and services.

George and Jones (2008)

Effective organisations needed an accurate understanding of customers' expectation.

Summers (2005)

Improvement through rapid and substantial gains in organisational performance by starting from scratch in designing or redesigning the foundation business development.

Small et al. (2011)

Business process involved any activity that was fundamental for fast delivery of goods and services to customers, or that promotes high quality and low cost.

George and Jones (2008)

Concurrent Engineering (CE)

Deal primarily with product design base, incorporating the constraints of subsequent phases into the conceptual phase and tightening of change control towards the end of the design process

Koskela (1992)

Last Planner System (LPS)

To achieve lean goals of reducing waste, increasing productivity and decreasing unpredictability mainly throughout a social process, by trying to make planning mutual attempt and by increasing the reliability of commitments of team members

Seppanen et al. (2010)

In construction, LPS was a method that forms workflow and deal with project variability.

Salem et al.(2005)

Teamwork

Teamwork was complementary skills groups of people with who were committed to a common purpose and hold themselves mutually accountable for its achievement, in which they develop a different identity and work together in a co-ordinated and mutually supportive way

Excellence (2004)

Value Based Management (VBM)

Value based management approach in which indicate that product value for the customers is considered product value while value for the workers and project participants was termed process value.

Bertelsen (2004)

OHSAS 18001

Steps taken to improve existing features, or the consistency of their application and elimination in frequency if particular undesired incidents

Mohd Yunus (2006)

Business Process Reengineering (BPR)

By having an efficient implementation in construction projects, OHSAS 18001 will provide a safe and conducive working environment at workplaces and all workers will feel secure and comfortable (Khalid 1996). As a key concept of LC, fewer accidents will occur and it will increase the rate of safety in workplaces. Hence, it will increase the productivity, profit and job satisfaction of the client due to the commitment of all workers.

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Table 4. Key concepts of lean construction in construction process Authors

Just-InTime (JIT)

Small et al. (2011)

Total Quality Management (TQM)

Business Process Reengineering (BPR)

Pre-construction

Design

Construction

Pre-

Concurrent Engineering (CE)

Last Planner System (LPS)

Teamwork

Value Based Management (VBM)

OHSAS 18001

construction Construction

Seppanen et al. (2010)

Construction

George and Jones (2008) Salem et al. (2006)

Pre-construction Construction

Preconstruction Construction

Construction

Construction

Mohd Yunus (2006)

Construction

Summers (2005)

Pre-construction Construction Use

Excellence (2004)

Construction

Bertelsen (2004) Koskela (1992)

Construction

Construction

Design

Construction

Pre-

Use

construction Construction

Table 4 explains the interaction of key concepts of LC in regards to the construction process. Construction process included preparation: appraisal and design brief design: concept, design development and technical design pre-construction: product information, tender documentation and tender action construction: mobilisation and construction to practical completion use: post practical completion (RIBA Plan of Work, 2012). The researchers such as Koskela (1992), Salem et al. (2006), George and Jones (2008), Small et al. (2011), Summers (2005), Excellence (2004), Seppanen et al. (2010), Bertelsen (2004) and Mohd Yunus (2006) described how to incorporate the key concepts of LC in the construction process. The majority of the researchers suggested pre-construction and construction are the best time to synergise the LC concepts. Both of these stages are crucial due to determination of material, equipment and labour during pre-construction (Koskela, 1992) and elimination of construction waste during construction (Yahya and Mohamad, 2011). The authors agree with the researchers but believe that some

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of the key concepts of LC should be introduced at the earliest stage e.g. JIT, teamwork, LPS and OHSAS 18001. By doing so, competent workers and project team can identify the waste and diminish volatility as well as able to control health and safety risk of construction project. In addition, the authors suggest that the end requirements should be taken into consideration (Jorgensen and Emmitt, 2008) and their involvement should be throughout the whole construction process starting from the preparation until use stage. 7. Discussion and Conclusion Based on the literature review, it can be concluded that the current application and implementation of LC in the Malaysian construction industry is still in its infancy or in a very early stage even though it is known to provide a good platform for the stakeholders to achieve value for money for their projects. Its full implementation in the Malaysian construction industry in particular is not an easy task as it will need more effort from all related parties such as the education system, the practitioners, related authorities as well as the clients of the industry. By incorporating health and safety in LC principles, the chances of success in achieving maximum value in construction projects will be very high. From the above discussion, it was clearly shown that LC as well as the process safety and health shared the same perspective, which is safer and conducive working environment will increase workers' performance at workplaces. Hence, it will increase the productivity of the project. LC principles have been applied by local construction players such as SSE Enterprise Sdn. Bhd. and PLB-KH Bina Sdn. Bhd. From the investigation, it was found that the understanding of lean is merely an academic knowledge even though lean approaches can be applied in the construction process. More information on how LC to be implemented to construction project should be provided in order to improve the lean practices among construction players. It is suggested that the government of Malaysia should initiate an official website to facilitate this LC concept. Besides, in order to make the LC concept to be more popular, the Construction Industry Development Board Malaysia (CIDB) should provide more opportunity for industrial training sessions to the practitioners. Moreover, lots of alternatives shown to the stakeholders on how to implement the LC in the construction project. Key concepts of implementing LC such as JIT, teamwork, LPS and OHSAS 18001 should be adapted, through research and further analysis as to familiarise the methods inclusively to the construction process. On the other hand, this area is believed to have potential for further research since many aspects can still be explored. The process of maximising value in the construction process from start to finish of the project must be observed. Moreover, there is a need for an indicator to measure LC performance. The indicator is prudent for continuous improvement. It is hoped that by having the process of LC to be implemented in the local construction management processes e.g. design process, material process and work process, it will be able to assist the industry to move away from the traditional construction and method of doing things, which is beneficial to stakeholders towards a more synergistic, sustainable and greener future hence resulted to a better value of future construction project. Future research in similar area, will be conducted on companies that have implemented LC concept by observing their practices on site. References Abdullah, S., Abdul Razak, A., Abu Bakar, A. H. & Mohammad, I. S. (2009). Towards Producing Best Practice in the Malaysian Construction Industry: The Barriers in Implementing the Lean Construction Approach. Retrieved 26 August 2011 from http://eprints.usm.my

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ScienceDirect Procedia Computer Science 100 (2016) 634 – 643

Conference on ENTERprise Information Systems / International Conference on Project MANagement / Conference on Health and Social Care Information Systems and Technologies, CENTERIS / ProjMAN / HCist 2016, October 5-7, 2016

The Integration of Lean Construction and Sustainable Construction: A Stakeholder Perspective in Analyzing Sustainable Lean Construction Strategies in Malaysia Ahmad Huzaimi Abd Jamila,b,*, Mohamad Syazli Fathia a

Universiti Teknologi Malaysia (UTM) Razak School of Engineering and Advanced Technology, Jalan Sultan Yahya Petra, 54100 Kuala Lumpur, Malaysia b Faculty of Industrial Management, Universiti Malaysia Pahang (UMP), Lebuhraya Tun Razak, 26600 Gambang, Kuantan, Pahang, Malaysia

Abstract The simultaneous implementations of Sustainable Construction (SC) and Lean Construction (LC) concepts/practices are feasible in a strategic approach to accomplish improvement in reducing waste, which resulted in both positive environment and economic outcomes. Although both concepts/practices are capable of attaining significant environmental and economical benefits, organizations still experiencing difficulty to integrate the concepts successfully. The literature indicates that the construction industry in many countries have encountered poor implementation and integration of both concepts. Therefore, this paper aims to lay the groundwork for future empirical study by investigating on various dimensions of SC and LC, where the theoretical and practical findings provided a foundation for integrating the two initiatives to yield the efficient use of valuable resources. © Published by Elsevier B.V. B.V. This is an open access article under the CC BY-NC-ND license ©2016 2016The TheAuthors. Authors. Published by Elsevier (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the organizing committee of CENTERIS 2016. Peer-review under responsibility of the organizing committee of CENTERIS 2016 Keywords: Lean construction; sustainable construction; stakeholder involvement; strategy

*

Corresponding author. Tel.: +603-2615 4524; fax: +603-2180 5130 E-mail address: [email protected]

1877-0509 © 2016 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the organizing committee of CENTERIS 2016 doi:10.1016/j.procs.2016.09.205

Ahmad Huzaimi Abd Jamil and Mohamad Syazli Fathi / Procedia Computer Science 100 (2016) 634 – 643

1. Introduction Lean construction (LC) promises outstanding results in managing the construction process and achieving the project’s goals by eliminating waste. In the case of Sustainable Construction (SC), systematic training and research are crucial to provide proper interaction and collaboration with the stakeholders, thus enhancing the quality of life for the future construction industry55. Usually, LC and SC practices are two separate and independent strategies, where Lean’s process goal is to improve economic standards, while sustainability aims to improve the environmental objectives. However, through enormous research and industry practices, it is found recently that the two practices are interdependent and shares the exact basics of waste elimination39. Therefore, components related to SC can be integrated into the concept of LC to enhance and preserve the natural resources, economic growth, and environment without compromising the future. This is possible because the integration of concepts will enhance the performance and the impact of building construction by realizing hidden cost reductions towards the environment 56,74 It is clear that the global construction industry will significantly benefit from adopting both SC and LC concepts, however the literatures revealed that the implementation process is fairly poor with slow or no progress. 16,22,67 Furthermore, lean process is problematic for the construction industry in many countries within the past years.9,10,16,25,49,57,72 Due to the actual scenario in the construction industry, many applied researchers have become increasingly interested in exploring the context of sustainable development, LC, and innovation. Despite these the heavy interest, a study by Common et al.,19 revealed that the emergence of lean culture within various European construction companies is actually lower than the expectation. Considerable gaps are found at the level of development as identified in the previous studies on LC within the context of structural and cultural aspects, namely human attitudinal, lack of adequate lean awareness and knowledge, and lack of top management commitment that hinders the successful implementation of LC in the UK construction industry19,67. Apart from the aforementioned aspects, some of the other factors that are hindering the successful implementation of SC were also discussed in the literature, namely inefficient strategy, improper management and leadership styles, inadequate stakeholder engagement, and reluctant to foster sustainability as cultural values.7,22,31,46 Koskela and Howell35,43 highlighted that the involvement of various stakeholders in the industry is essential to deliver successful projects, which will reflect towards substantial effort in achieiving a greener environment28,61. Based on the above explanation, our study aims to provide the insights of the theoretical integration of LC and SC for the application and practice of Sustainable Lean Construction (SLC). The research work herein will contribute new ideas on the implementation of LC and SC, and concurrently enhances the performance and the productivity of construction projects. The central research question of the proposed research is: What are the fundamental characteristics of SC and LC, how can SC and LC be integrated strategically into SLC? The structure of this paper is as the followings, section 2 introduces the research methodology that details out the various aspects of the proposed research. Section 3 aims to provide a comprehensive review that supports the contextual settings of SC, LC, and the disputes of integrating the SC and LC concepts into an overall concept of SLC. Subsequently, section 4 analyzes and synthesizes the literatures in the area of SLC to develop a framework on the strategy of SLC integration. 2. Research approach The focus of this paper is on SLC conceptualization and implementation, and the paper consists of an integrative literature review50,65, and a coding framework15. In the literature review, the aim is to provide a better understanding of the SLC concept in both theoretical and practical aspects, hence the concepts of SC and LC are explored, discussed, and synthesized into an SLC concept. Theoretically, sustainable construction emphasizes reductions in building energy use, water use, materials employed, and pollution4. On the other hand, lean construction emphasizes reductions in the waste present in the processes used to design and construct buildings in producing products valuable to the customer, while eliminating all other unnecessary activities, defined as waste34,42. SC and LC both

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exhibit significant synergies on minimizing resource use as both “strive for the efficient use of resources through the reduction of waste”64, while the practical contribution to the current practice and the future empirical work are explained in the findings section and future work section within this paper. In a nutshell, this paper improves the existing literature by integrating SC and LC concepts, where the major research highlight is that the integrative approach adopts the stakeholder approach. The importance of choosing the stakeholder approach is to understand and analyze the project stakeholders’ environment, consequently enabling to determine the right type of approach according to the stakeholders1,21, where approaches can be either SC, LC or an integrated SC and LC concepts. 3. Findings of the review The systematic literature review of the previous empirical studies is presented in Table 1, where all three aspects of SC, LC, and SLC will be discussed, namely the theoretical foundations of the literature, the principles that underlie these foundations, and the sources in the literature that reports these foundations and principles. Under the subsections within this section, the contents of Table 1 will be explained in detail. Table 1. SC and LC practices. Theoretical foundations

Principles

Sources

Sustainable construction practices -The integration of Social, Economic, and Environmental attributes -Design & Procurement

-Innovative business strategies that improved the lifecycle of the production with additional focus on the waste reduction.

8,14,17,59,70

-Improved the project’s lifecycle value through green design and the promotion of best construction procurement practice throughout the supply chain -Enhanced the company’s capacity towards technology & innovation to empower sustainability concept throughout the construction process.

23,66,71

-The organizational structure & process.

-Reorganized the organizational process to facilitate the implementation of sustainable policy and strategy

30,53

-Education and training

-Increased organizations’ commitment to SC through better education and training for project stakeholders. -Development of existing benchmarks that evaluated the companies’ environmental and social performance and consequently identified the areas for improvement

18,24,58

-LC was designed as a production management based approach for project delivery: a new method to design and build capital facilities. -New production philosophy to maximize value, minimize waste and resources to enhance customer values.

5,12,43,52,54,80

-A balanced use of people, materials, and resources. -Reduced costs, eliminated waste and delivered projects on time.

51 27,34,42

- An enormous number of construction projects suffered due to the inadequate attention on environmental issues. -The crucial elements to the success of SLC implementation that affected the structural relationship between cultural values and coping behaviors in implementing SLC concept.

72

-Limited experience and knowledge led to the significant amount of waste.

41,79

-Technology and innovation.

-Measurement and reporting

Lean Construction -The revolution of manufacturing principles in building environment and meeting customer needs. -Balanced use of resources

Disputes to integrating SC and LC concepts. -Lack of focus to environmental elements. -The integration of team accountability, base organization, cultural issues, and leadership management -Inadequate commitment and

22,38,40,76

63,77,81

26,35,56,57,68,82

6,10,32,37,44,47,54,55

Ahmad Huzaimi Abd Jamil and Mohamad Syazli Fathi / Procedia Computer Science 100 (2016) 634 – 643

knowledge integration. -Transparent communication.

-The effects of contractual arrangements design-build (DB) on communication. -The commitment to open, frequent and genuine communication at all levels of the integrated design team.

36 6,37,44,62,74

3.1. Sustainable Construction Sustainable construction is a comprehensive integration of environment, social and economic issues. The aspects that are important in this matter are the quality of life, work efficiency, and a healthy work environment. The practices in the concept of SC enables to enhance the capacity of technology and innovation, which directly improves the strategy and practice of construction business right from the start and up to the end process that manages the waste.22,76 By implementing a clear sustainability strategy, contractors will be enable to identify and select their specific SC practices that focuses on their commitments and improves their knowledge. Most related researches reported that proper education and training will increase stakeholders’ commitments and knowledge at every level. Furthermore, according to Abdullah et al.,3, commitment and knowledge were the vital elements to a successful implementation of sustainable concepts.22 The case studies so far have justified that firms will benefit more from the sustainability implementation if it is holistically applied throughout the organization rather than only in the projects.11,41 Meng et al.,56 argued that insufficient commitment and knowledge had led to one of the common factors that produced the current barriers.37 Apart from that, adequate knowledge will boost stakeholders’ performance and motivation, especially in an increasingly technology-savvy environment with more transparent workforce that provides an enhanced communication medium and sharing of knowledge.76,77 Despite the benefits of SC, unsustainable design and construction processes, and constant degradation of the environment due to the construction process still exist in most developing countries, and Malaysia is part of the negative processes.54,55 In line with this issue, Lam et al.46 explored factors impeding to the successful execution of sustainable specification in construction. Some of the factors are cultural barriers, lack of green technology and techniques, reliability, quality of specification, leadership and responsibility, stakeholder involvement, and guide and benchmarking systems.22,67,68 On the other hand, both developed and non-developed countries struggle with the SC concept. Although several efforts have been carried out by developed nations to fully transform into sustainable construction practices, however a large number of empirical studies reported that many barriers prevent the development of sustainable construction in these countries.7,13,31,67 Many sustainable practices that comprised of topics on safety, efficiency, productivity, and waste minimization, are actually interlinked.27,41 and difficult to be implemented. Accordingly, Houvila and Koskela34 strongly suggested that a concrete methodology for implementing all these sustainable construction topics was imperative for a sustainable development. 3.2. Lean Construction The major concern related to the ‘rethinking construction’ as reported by Egan 24 is the development to improve the culture, organizational and managerial style of the industry to breakthrough the hurdles, attitude, roles, relationships, actions and communications among the project stakeholders.43,68 Likewise, the culture, and the organizational and managerial styles are the crucial pillars for a continuous improvement, which implied a constant delivery of greater value and increasing mutual competitive advantages.3,43 Through stakeholder collaboration and continuous improvement, the team members can identify opportunities to eliminate the activities that do not add value.56,68,82 Conversely, Lim51 suggested that Lean is all about achieving a balanced use of people, materials, and resources. In other words, lean implementation facilitates an organization to reduce costs, eliminate wastes, and deliver projects on time.27,34,42 According to Bertelsen12, LC is similar to the current practice that aims of to enhance customer satisfaction and performance of the firms. The primary objective is to minimize the waste to improve and support the new

637

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production philosophy.26,35 Howell35 characterized LC as a conceptual foundation and understanding of waste resource, which explains the projects that are managed on a traditional basis experienced adversaries and difficulty in controlling the outcome. In traditional case, the practice is to optimize the piece, while lean aims to optimize at the project level, and it requires a different approach towards managing work. 79 Though LC efforts could have been proven to be highly rewarding for the construction industry, it does not seem to be adopted in the global construction industry.67,68 Furthermore, there appears to be some significant structural and cultural barriers towards the adoption, namely inadequate lean awareness, knowledge and skills, and lack of top management commitment, technology limitation, poor implementation strategy, inefficient stakeholder relationship management, the lack of supportive organization and teamwork, inefficiency communication in sharing vision and consensus, and other minor problems that consequently hindered the construction industry from following the objectives of lean concept. 3,16,54,55,68 Malaysia, as a developing country, the concept of lean construction in the industry is still considerably new and fresh.55 A major reason that Malaysia has limited implementation and scarce research framework of lean concept is a concomitant factor with the developed nations that similarly hesitate to adopt the concept. 3 According to Johansen and Walter79, the implementation of the lean concept in the construction industry is still restrained and sluggish. This issue had been supported by Common et al.,18 based in the United Kingdom and by Johansen and Walter79 based in the Netherlands, where these authors clearly stated that there has been a slow progress in the construction industry in promoting lean concepts. Although many companies employed skilled professionals that are well versed in the construction processes and aware of the changes and improvements within the industry, there are still issues hindering the implementation of lean concept. In the literature, it was evident that applying the lean principle or tool will be insufficient without a consistent strive for a lean culture.16,54,68 Therefore, it is essential to extensively engage in the lean concept in a balanced approach throughout a system with the following characteristics, namely personal focus, collaboration, and motivation in delivering value to customers.33,79 Therefore, our study strives to improve these lacking areas to enhance the performance of construction projects, which consequently will provide a better implementation platform for SLC. 3.3. Integrating SC and LC into SLC Some literatures contend that the theory of lean construction is already offering a conceptual basis and potential for novel methods and tools that foster sustainability concept at various perspectives. 3,34 Integration efforts are required for further development with the objective of enhancing the quality of life through the integration of SC and LC.47,54,55 The Pentagon and Toyota South Campus are two practical cases that have been thoroughly examined on the integration process of SC and LC concepts. 41,47 A study of the Pentagon renovation project showed that the integration process saved both money and time by demonstrating a strong relationship between sustainability and lean concepts. These projects have been completed by using an innovative contracting strategy and delivery process designed to eliminate many contractual barriers. As a result, the projects were able to build highly efficient facilities that are completed within project budget and schedule. 41,47 Due to the significant impacts from the construction activities toward the society and environment, global government bodies have introduced various policies and regulations to control the relative impacts. 76 However, it is found that the majority of the projects have suffered due to lack of consideration towards the environment. 72 Similarly, Scherrer-Rathjea et al.,69 stated that although the significant benefits offered by LC relative to waste reduction and improved business profit, the integration of LC and SC may result in better cost saving, waste reduction, and environmental impact.34,37 Therefore, there are actually synergies between lean and eco-sustainability. The strengths and weaknesses of lean and eco-sustainability revealed the significant opportunities for integrating initiatives to potentially achieve the LC and SC objectives.41,48 In order to effectively achieve the implementation of SLC, commitment and knowledge are the crucial elements.41,79 An empirical study conducted by Koranda et al.,41 investigated the relationships among worksite, design, environment, and SC and LC in perspective of small construction projects. The empirical evidence justified that many project managers were found to have insensibly applied lean concepts (such as the reduction of on-site inventory), and have limited experience and knowledge on sustainable and lean projects that led to a significant

Ahmad Huzaimi Abd Jamil and Mohamad Syazli Fathi / Procedia Computer Science 100 (2016) 634 – 643

639

amount of waste. Moreover, Koranda et al.41 ascertained that contractual arrangements were found to limit the interaction and the integration knowledge between designers and contractors. Frequent communication between parties helped to integrate knowledge and information related to, for example, regional conditions, materials, practices, and uncertainties.6,44 In the case of a Design-Build (DB), the project owner provides contract to DB firm during the early stage of the project development process, therefore the communication between the designers and contractors occurred frequently and openly than it does in conventional DB projects.36,74 Such communication helped the designers and contractors to align their project objectives and reduced design construction conflicts, which further facilitated the application of LC and SC.37,62 4. Discussion: Future work for improvement

Fig.1. A simplified model for integrating SC and LC in a Construction Project. Koranda et al., (2012)

It is widely acknowledged that developing countries have experienced great challenges in finding a holistic approach to guarantee sustainability in the construction industry. An enormous framework of literatures is available on the problems encountered by the global construction industry that is discussed in the previous sections. However, limited research has been carried out by academics and practitioners on the challenges faced by the local countries specifically in the Malaysian construction industry (MCI). 3,4,22,51,54,55,67 Abdul Rahman et al.,2, found 45.9 percent of delays actually occurred in the completion dates during the construction stage, and the construction projects were not cost effective.56 Another significant challenge in the MCI is an inadequate consideration of the important component of economic growth and social development,3,4,31,55 which has been the source of significant negative impact on the physical environment, such as soil erosion and sedimentation, flash floods, destruction of vegetation, dust pollution, noise pollution.43,56,68,75 There is an urgent need to address these issues in the MCI, where sustainability challenges have been taken into consideration. Since, the LC has demonstrated as sustainability, the adoption of LC in construction practices may lead to pollution reduction.20,54 Based on the literature review of the crucial elements on integrating SC and LC, our future empirical study will innovate a new operational framework by utilizing the model of integrating LC and SC practices. The similar model is shown in Fig.1 that was proposed by Koranda et al.,41 which will be an interpretation system in the context of project stakeholder analysis. The objective of the model attempts to simplify the process by integrating the findings of the study with the existing techniques and literature on the implementation of SC and LC concepts. The components of sustainable construction bearings that have value, focus on waste elimination, which are part of a process that will affect project schedules and costs will be documented extensively hence to integrate with lean construction. The components

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mainly emphasize the fundamental contribution of the flow view (eliminating waste). 42,43 The primary concerns of this model are two key issues, namely conflicts of delivering values and project stakeholder collaboration for integrating the SC and LC concepts. Every stakeholder should concentrate on maximizing the gains from a construction project,21,35 thus, the project team needs to clearly define the values for their project, identify waste, and unnecessary processes in their project.43 These values should be identified in the early stage of the project, which should be eliminated during the planning, scheduling, and construction stages. 41 The involvement of project managers from planning until project completion is vital in ensuring the materials are delivered efficiently. Therefore, lean process should be applied by all parties at all stages, aspects, and activities of the end-to-end project cycle.3,37,56 As a result, SC and LC implementations may be easier if the stakeholders are able to determine the right type of action at a various stages.1,21 The performance indicators are also highlighted in the bottom of the column of Fig.1, these indicators are the essential conditions for the designers and contractors to be able to integrate the LC and SC concepts. By checking these indicators, stakeholders may have a better understanding of their position in the integration progress of LC and SC.5,21,68,71 On the contrary, the model proposed by Koranda et al.,41 was derived from the case studies of small and medium construction projects, which only involved the architects, engineers, and contractors from the construction organizations. However, our study will extensively engage the project stakeholder analysis, simply because stakeholder engagement is highly regarded as part of the dimensions of SC practice. 29 In other word, stakeholder engagement is important because each stakeholders can have different perceptions of what constitutes the success of a project.1,21,61 The improved version of the model enables the project team members to recognize each LC and SC functions and priorities, therefore LC and SC are effective when all of the construction stakeholders involve holistically. The extensive collaboration is crucial among general contractors, construction managers, subcontractors, and material suppliers, of whom are committed to the concept that will result in an optimistic flow of the activities at different phases of the project.37,44,47 In future study, our empirical framework will also include constraint analysis as part of the activity , process and practice within the end-to-end production or project process that prevents inefficient flow. The analysis can be a useful feedback and gauging system for review and correction, which enables the stakeholders to identify the problems and provide continuous improvement effort because each constraint will add time and cost. 1,76 Once problems are identified, performance improvements should be carried out to eliminate or minimize each constraints to accomplish greater value.3,43 The improved model aims to apply an integrated stakeholder approach by using the Aaltonen1 themes with incentives to address the challenges of integrating SC and LC practices. The approach increases our understanding on the variance of the project stakeholder analysis, because previous literatures have provided limited attention to the project stakeholder analysis.1,61 Accordingly, the proposed model can be a comprehensive guideline for each stakeholder to articulate their performance requirements (the real value they desire in their new buildings), and allow their teams to develop solutions 21,55,68 by analyzing and understanding the nature of the issues related to LC and SC. As a result, organizations will have an understanding of the required improvement efforts, where these efforts should be focused on obtaining the best results to maximize value with fewer resources utilized throughout the integration process of LC and SC concept. 16,47,64 5. Conclusion This paper discusses what the characteristics of lean construction (LC) and sustainable construction (SC) are and how sustainable lean construction (SLC) serves to be effective strategies in establishing the linkage between LC and SC. The fields are at the forefront of rapidly emerging construction management strategies, as considerable publications exploring sustainability and lean construction date from recent years. Our future studies envision the main opportunities and challenges in extending the proposed model by incorporating Building Information Modeling (BIM) and Industrialized Building System (IBS) as the common tools that act as catalysts in developing conceptual framework for lean and sustainable integration. A simplified model as shown in Fig.1 can be used as a benchmark or reference for lean and sustainable improvements with the help of industry experts, project practitioners, project owners and stakeholders. The model demonstrates how the strategic implementation facilitates in LC and SC integration from design phase to the completion phase of a project. It indicates a systematic approach of LC and SC concepts that can be extensively used to achieve LC and SC integration.

Jestr

JOURNAL OF

Journal of Engineering Science and Technology Review 10 (4) (2017) 170- 177

Review Article

Engineering Science and Technology Review www.jestr.org

The Practical Relationships between Lean Construction Tools and Sustainable Development: A literature review M. S. Bajjou*, A. Chafi, A. Ennadi and M. El Hammoumi Science and Techniques, Sidi Mohammed Ben Abdellah University, B.P. 2202 - Route d’Imouzzer – FES, Morocco Received 16 February 2017; Accepted 14 September 2017

___________________________________________________________________________________________ Abstract The construction industry is considered among the largest consumers of natural resources (non-renewable materials, fossil fuels, water...). It is also an important source of generation of solid waste and greenhouse gas emissions. In addition to its negative impacts on the environment, most construction projects are characterized by the non-respect of the triptych (Cost, Time, Quality) and a high accident rate compared to other sectors. Lean construction (LC) is a new production philosophy which has the potential of bringing innovative improvements in the construction sector. It is a systemic approach to meeting customer expectations by maximizing added value and reducing all forms of waste. Based on international standards (AFNOR, GRI, UNEP, ISO 26000...) and recent researches published in the most reliable databases, this study aims at exploring the concept of sustainable development in the context of the construction industry and examines how the LC tools (Prefabrication, Value Stream Mapping, Poka-Yoke, visual Management, and 5S) can have an impact on the three dimensions of sustainable development (environment, economy, society). This work brings a new reflection by constructing an interaction matrix between the Lean Construction tools and sustainable development. Keywords: Lean Construction, Sustainable development, Interaction matrix

____________________________________________________________________________________________ 1. Introduction The sector of construction represents an integral part contributing tangibly to the economic growth of developing countries. At the national level, the sector of construction is considered amongst the most dynamic and the most promising of the Moroccan economy, it contributed by 6.3% of total value added created in 2014 with an increase of 4% compared to 2013 [1]. It employs nearly a million people (9,3% of the active population) [2]. On the other hand, even if the construction industry participates in strengthening the national economy and reducing the unemployment rate, this sector also has a huge impact on the environment compared with other industries, and it is considered within the most polluting sectors [3, 4]. The construction industry is a very large consumer of non-renewable resources. Similarly to its damaging effects, it is also an important source of natural resources waste (non-renewable materials, water...), solid waste generation and greenhouse gas emissions. In Morocco, almost 9 million tons of solid waste are dumped every year in nature [5]. Besides that, the Moroccan construction industry is considered as the largest consumer of energy; it accounts 36% of final energy consumption and 32% for the manufacturing sector [6]. Moreover, it is considered among the sectors of activities having a great impact on air pollution and the deterioration of the ozone ______________ *E-mail address: [email protected] ISSN: 1791-2377 © 2017 Eastern Macedonia and Thrace Institute of Technology. All rights reserved.

doi:10.25103/jestr.104.20

layer; it is a source of 45 million ton of CO2 (in 20 years, CO2 emissions have increased by more than 200 %) [7]. In addition to its negative impacts on the environment, most construction projects are characterized by high variability and high accident rate compared to other sectors [8]. According to the last studies carried out by Lean Construction Institute (LCI) [9], the sector of construction is characterized by a ratio production/waste higher than that of the manufacturing sector as could be seen in Fig. 1.

Fig. 1. Comparison of Production\/waste ratios between manufacturing sector and construction sector

It has become crucial to seek creative and innovative solutions that ensure better and more optimized modes of management. Because of its great potential in achieving customer expectations in terms of increasing the value and reducing all forms of waste, the Lean Construction philosophy is considered an alternative approach which can bring revolutionary changes to the construction industry. The LC is a concept that derives from the manufacturing industry, adopted in the industry of construction with its objectives to minimize waste and maximize the value added

M. S. Bajjou, A. Chafi, A. Ennadi, and M. El Hammoumi/Journal of Engineering Science and Technology Review 10 (4) (2017) 170-177

in construction projects. LC is a proven method for the management and optimization of the construction process, hence the requirements of customers can be reached using good resources and as well its ability to provide the best quality from the first time. Various lean tools for achieving sustainable development have been discussed by several authors. However, in the literature, there are only a very few studies that have explored various issues of sustainability by means of lean construction initiatives and established the benefits that can be derived by applying the lean tools. The purpose of this study is to analyze the concept of sustainability in the context of the construction industry based on a literature review of scientific contributions published in reliable journals. This work brings a new reflection focusing on the relationship between lean construction tools and the three challenges of sustainable development (environment, economy, society).

Economy

Cost saving

1

Increase added value5 Time reduction1 Partnering3 Competitiveness2 Waste Reduction1 Measure customer satisfaction5 Responsiveness3 Flexibility2 Increase workers productivity1 Material and resources6 Energy efficiency6

[3, 4, 14, 15] [3, 4, 11, 14, 15, 16] [3, 11, 13, 14] [3, 11, 14, 15] [3, 13] [6, 11] [3, 11, 13, 14, 17] [11,15, 16] [15, 18] [4, 14, 15] [11, 15] [3, 4, 16, 18, 19, 20] [3, 4, 16, 18, 19, 20] [3, 4, 16, 18, 19, 20] [3, 4, 19, 18, 20] [3, 16, 20] [16, 18, 20] [4, 16]

Emission of greenhouse gases8 Water efficiency6 Environment Solid wastes9 Resource depletion6 Pollution Prevention7 Production of toxic [3, 4, 16, 21] products7 9 Solid waste treatment [19, 22] Use of land6 [3, 4, 18] Working conditions10 [3, 4, 16] Health and safety (e.g. employees injuries, [3, 11, 16] fatalities) 10 Labor/Management [3, 11, 16] Society Relations10 11 Employment contribution [3, 4, 16] Education/training11 [3, 4, 16] human resource [3, 16] development11 12 Employment [3, 4, 12, 16, 23]

2. The concept of sustainable development 2.1 Sustainable construction Sustainable construction is mainly defined by the industry that ensures the conservation of natural resources throughout the life cycle of the building (energy, water, non-renewable materials), optimizing the consumption of raw materials in purpose to reduce the deterioration of the environment and to ensure social and economic comfort [10]. A sustainable and ecological construction project must necessarily take into account the objectives of sustainable development at every stage of decisions: design, construction, use, and demolition. In addition to these earnings to the level of socioeconomic development and the protection of the environment sustainable construction practices ensure other intangible benefits such as strengthening the company's name in the market, the resistance to global competition, improving the quality of infrastructure and creation of working conditions guaranteeing motivation and employee satisfaction [11].

The analysis of the data in Tab. 1 has allowed us to identify twelve main factors, as shown in Fig. 2, spread over the three dimensions of sustainable development (Economy, Environment, and Society). These main factors encompass the thirty factors that were found in the literature and international standards. They are identified in Tab. 1 by the exhibitors ranging from 1 to 12 depending on the correspond issue. These main factors will be used in the development of a matrix of interaction between LC tools and the three dimensions of sustainable development.

2.2 The main factors of sustainable development There are several definitions of sustainable development in the literature, especially that sustainable development is a broad concept that has been adopted and interpreted in many contexts. The most popular definition of sustainable development is that given in the Brundtland report [12]: “Development that meets the needs of the present without compromising that ability of future generations to meet their own needs”

3.1 Origin The study carried out by Pappas [24] in 1990 noted that only 11.4% of the time on construction site created addedvalue. Other Swedish studies in their turn, have observed that the operations which create added value represent only 30% of time spent on a construction site [25, 26]. LC is a new philosophy of production, representing the adaptation of the concept Lean manufacturing with the peculiarities of the construction industry. Due to its great potential in fulfilling objectives in term of increasing the added value and productivity LC has gradually interested stakeholders of the construction industry. The discussions relative with the concept of LC began in 1992 when Koskela thought of introducing Lean philosophy

In order to assess the impact and contribution of the lean construction philosophy in sustainable development, we have clarified the key factors of the three dimensions (economy, environment, and society) based on international standards (AFNOR, GRI, UNEP, ISO 26000...) and on recent research published in the most reliable international journals. The most common factors of sustainable development are shown in Tab. 1. Table 1. The factors of sustainable development Dimensions factors References Productivity/profitability1 [3, 4, 13, 14, 15] Quality1 [3, 4, 11, 15, 16]



Innovation/R&D4

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in the management of construction projects [27]. While taking as a starting point the model of Toyota Production System (TPS), Koskela invented theory TFV (Transformation, Flow, Value) [13] as is shown in Tab. 2.

The most common definitions used in the literature are cited in Tab. 3. Table 3. Definitions of Lean Construction

Fig. 2. The main factors of sustainable development

Table 2. TFV (Transformation-Flow-Value) theory of lean construction

Definitions

Dupin [28]

2014

LC aims to create value for the customer by the elimination of the waste, supported by collaborative project management tools, as part of a systematic and rigorous approach of continuous improvement.

Howell and Ballard [29]

1998

The LC is designed to better meet the needs of customers by using fewer resources.

Koskela [27]

1992

A way to design the production system to minimize waste of materials, time and efforts, in order to generate the maximum possible value of the end product.

Flow

Value

Concept of production

A transformatio n of inputs into outputs

A flow of materials, composed of transformati on processes, inspection processes, movements and waiting

A process where the value for the customer is created by the realization of its requirement s

The main Principle

To have an efficient production

Elimination of waste (non-valueadded activities)

Elimination of the losses of value (value obtained by report to the best possible value)

Practical contributio n

Take care of what must be done

Take care that what is nonnecessary should be reduced to the maximum

Take care to meet customer’s requirement s in the best possible way

3.3 Waste in the construction sector The seven forms of wastes in the construction industry are: waiting, motion, over processing, overproduction, transportation, inventory and defects [30]. Many scientist and professionals consider that the negligence of the seven form of waste by stakeholders during the construction phase is the main cause of the problems of cost overruns and delays in the construction industry [11, 28]. LC considers the construction process as a process flow, combined with transformation activities, contrary to the method of traditional construction which focuses only on the improvement of the steps which create the added value. According to Dupin [28], value-added activities (Direct work) don’t exceed in most of the time 32% of time spent on site, as shown in Fig. 3.

3.2 Definitions of Lean Construction LC philosophy doesn’t have a single definition in the scientific references, it’s still evolving as the academic research, in particular doctoral research, feed this concept.



Year

Overall, it can be concluded that LC is a new way to organize the management of construction projects in such a way as to reduce the sources of waste and generate the maximum value for the customer using the least resources.

3. Lean Construction

Transforma tion

Researchers

Fig. .3. Proportions of activities generating waste in the construction industry

172

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Most searches are focused more on the economic issues of the construction industry and optimization of the triptych (quality, cost, time). Various lean tools and techniques for enabling sustainability have been discussed by several authors. Some studies have explored various issues of sustainability by means of lean initiatives and established the benefits that can be derived by applying the lean principles/tools. This work follows the new paradigm of sustainable management of the construction projects as illustrated in Fig.4.

3.3 Lean Construction tools Many researchers have confirmed the usefulness of the LC concept for projects of construction [4, 15, 31]. The main advantage that companies could reduce the costs invested in construction projects by using fewer resources and reducing waste on production sites. In addition, by having a proper project planning, it would shorten the duration of the construction project. Based on an analysis of the scientific research conducted in several countries, we found that the most appropriate LC for the construction industry are as follows : Last Planner System (LPS), Visual management (VM), 5S, Value Stream Mapping (VSM), Building Information Modeling (BIM), Prefabrication, Analysis of roots causes (5 Why, the Ishikawa diagram , PDCA…), Just In Time, Poka-Yoke, as shown in Tab. 4.



Table 4. Lean Construction tools most used in the construction industry

×

×

×

[9]

×

× ×

×

×

×

×

[28]

×

× ×

×

×

×

×

[33]

×

Poka- Yoke

×

Just In Time

BIM

Root cause analysis Prefabricatio n

VSM

[32]

5S

VM Last planner system

Researche rs

×

Fig. 4. The new paradigm of sustainable management of the construction projects

×

[34]

In this study, we will focus on the direct interaction between five LC tools (Prefabrication, Value Stream Mapping (VSM), Poka-Yoke, Visual Management (MV), and 5 S) and twelve mains factors of sustainable development.

4.1 Prefabrication The existing literature has identified some modern methods as a means of reducing the production of waste in the construction industry. Prefabrication is one of the new techniques to ensure that the components are manufactured and assembled off-site. Several practical cases have shown the efficacy of this technique in reducing waste. For example, the two studies [37, 38] show that the tendency of the waste in the construction projects can be reduced to 52% and 84.7% respectively, compared to the traditional construction. The contribution of prefabrication in promoting the sustainability of construction projects, according to the three facets of sustainable development, is illustrated in Tab. 5.

4. The contribution development

Table 5. The contribution of prefabrication in sustainable development

×

×

[35]

×

×

×

×

×

[30]

×

× ×

×

×

×

[31]

×

×

×

×

×

[11]

×

× ×

of

×

LC

×

tools

×

in

sustainable

Dimensions

The promotion of the economy without taking into account other dimensions of sustainable development will certainly generate adverse effects on the environment and social comfort (health, safety, employment...). As well, the availability of natural resources on our planet (fossil fuels, water, steel, wood...) continues to decrease. Sustainable development is a development that meets the needs of the present without compromising the ability of future generations to meet their own needs. Indeed, Sustainable construction is the response of the construction industry to meet the challenge of sustainable development [31, 36]. In the literature, there is very little research which takes into account the contribution of LC philosophy on the three aspects of sustainable development (economy, environment, society).



Environment

173

Practical contributions

Ref

Reduces the impact on the environment due to the transfer of a large part of the construction process to a specialized factory in prefabrication. All these facts can be translated into many benefits such as less : storage of raw material, noise, air pollution (dust), waste and energy consumption

[34]

Prefabricated components are more likely to be easily

[14]

M. S. Bajjou, A. Chafi, A. Ennadi, and M. El Hammoumi/Journal of Engineering Science and Technology Review 10 (4) (2017) 170-177

Table 6. The contribution of Value Stream Mapping in sustainable development

disassembled in the demolition phase which facilitates their treatments (reuse, recycling, etc) and reduces solid waste

Economy

Selection of non-toxic, reusable and recyclable materials during the design phase.

[39]

Reducing waste on site reduces construction cost, allows to respect the deadline and to increase the quality of the project.

[38]

The development materials

Society

of

new

[14]

Flexibility and adaptability

[14]

Provides safer working conditions (e.g., Reducing dangerous tasks such as welding, cutting that may threaten the worker's safety)

[37]

The strengthening of a prefabrication industry will certainly contribute to the creation of employment opportunities and the development of the technical skills of the staff.

[34]

Dimensions

Practical contributions

Ref [40]

Environment

Allows to measure the consumption of any type of resource (water, energy, materials...), and quantify the sources of pollution (waste, emissions released into the atmosphere) The detection of the sources of waste allows to reduce the financial burden of the project and to shorten the time of completion of the project.

[14]

Economy

Facilitate workflow (load balancing, reducing the complexity of the process, minimizing unnecessary travel ...)

[28]

Society

4.3 Poka-Yoke Poka-Yoke, a Japanese word, is simply a mechatronics device that operates as a mistake-proofing to automatically prevent defects from flowing through the process (Fig. 5). Although this technique was used for the first time by Toyota to improve the quality of its products, the ideas behind this concept could be used to improve the productivity, quality, and safety of staff on construction sites. A typical example, such as controlling the addition of water during the production of mortar, as could be seen in Fig. 6.

Despite the great advantages of prefabrication, this technique shows some disadvantages. At the economic and social level, less labor is requested for projects based on prefabrication, thus fewer employment opportunities especially for staff working on construction sites. At the environmental level, this process can consume more energy for the transport of prefabricated products and emit more air pollution [14, 39]. A contractor applying prefabrication technique in its project should absolutely identify the best method of supply by using a holistic approach during the life cycle of the project.

Fig. 5. Using the Poka-Yoke devices in the construction process

4.2 Value Stream Mapping Value Stream Mapping (VSM) allows to graphically representing the set of steps constituting the construction process in such a way that the user of this technique can easily understand the circulation of the flow (materials, information). According to [14], in contrast to traditional methods the VSM helps to identify activities adding value for the customer and those without added value (non-value added activity). By analyzing the consumption of certain materials (brick, wood, concrete) in the walls construction process Rosenbaum [40] has verified the usefulness of the VSM in promoting the three dimensions of sustainable development. The contribution of the VSM in the promotion of the sustainability of construction projects is shown in Tab. 6. Fig. 6. Using Poka-Yoke devices during mortar production process



174

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Generally, this activity is carried out manually, without any strict control of water consumption which affects the quality of produced mortar. According to Dos Santos [41], the cost lost to solve the problems of non-compliance, errors and changes in construction projects are approaching 10% of the total project cost. The contribution of Poke-Yoke in the promotion of the sustainability of construction projects is shown in Tab. 7.

Make easier the sorting of the solid waste Reduce the variability of the construction process Economy

Table 7. The contribution of Poka-Yoke in sustainable development Dimensions

Practical contributions

[43]

Society

Ref

Strengthens the company position amongst competitors and gives confidence to the customer

[44]

A well-organized workplace allows to security and productivity among employees that the main cause of accidents on construction site is due to disorder noticed in site of construction

[8]

Reduces the consumption of resources (water, materials, energy) Environment Control emissions of pollutants (greenhouse gas, solid waste)

[41]

[41]

Economy

A positive impact on the triptych (quality, cost, time), therefore companies can better respond to customer requirements.

[8]

Society

The Poka-Yoke devices could also protect workers against excessive heat, noise, and some other dangers. In some cases, these devices are used as alarms to prevent labor from approaching or cross (e.g. Fall of objects, concrete in waiting for drying…)

Fig. 7. The traditional method of organizing construction sites

Besides these advantages, the implementation of this technique in construction projects will definitely contribute to the reinforcement of a specialized industry in developing Poka-Yoke devices, so more employment opportunities will be created. Training on this new technology will be necessary to improve the skills of the workforce working on construction and familiarize them with these new devices which lead to ongoing staff development and continuous improvement of the process of construction. 4.4 Visual Management and 5S 5S is the acronym for Sort (Seiri), Simplify (Seiton), Sweep (Seiso), Standardize (Seiketsu), and Self-discipline (Shitsuke). It helps to make a suitable site for the flow of value-added activities by holding everything in its place. The 5S process is considered among the first steps that an organization should take in implementing the LC philosophy. Visual management makes the construction process transparent, simple and safe for all stakeholders on site through digital billboards, signs of security and graphical dashboards. These tools allow to facilitate enormously the construction process and to improve the performance of the communication between the coordinators of the project. The comparison between Fig. 7 and Fig. 8 shows the usefulness of the visual management for the organization and transparency of construction projects [42]. The contribution of the visual management and 5S in the promotion of sustainability of construction projects according to the three facets of sustainable development is shown in Tab. 8.

Fig. 8. Organization of construction sites based on visual Management and 5S

4.4 Synthesis & Discussion Sustainable construction is a new concept that requires checking the objectives of sustainable development at all stages of decision making (design, construction, use, and demolition). In this study, we were based on the analysis of concrete results that have been observed during the execution of several projects of sustainable construction in many countries (United State, United Kingdom, China ...), and especially those adopting a strategy of resources optimization according to the LC philosophy. The objective of this study is to examine the practical relationship that may exist between the LC tools (prefabrication, Value Stream Mapping (VSM), Poka-yoke, visual management (VM), and 5S) and the sustainable development issues, which allows to have a feedback on the

Table 8. The contribution of Visual Management and 5S in sustainable development Dimensions Environment



Practical contributions

Ref

Reduce the waste of materials in stock

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level of impacts, either positive or negative, related to the application of the techniques of LC in sustainable construction projects. Tab. 9 represents an Interaction matrix that allows identifying the impacts of the different LC tools studied in this work. These impacts are divided into three categories: environmental, economic, and social.

both positive and negative. At the environmental level, prefabrication brings great benefits for sustainable construction by the use of non-toxic, recyclable, and easily removable materials during the phase of the demolition of building structures. However, this technique requires more energy resources for transportation of prefabricated products, therefore more greenhouse gases will be emitted into the atmosphere. At the social level, the strengthening of a structured prefabrication industry will certainly contribute to the creation of employment opportunities, the development of technical skills of staff and the improvement of working conditions as a result of the transfer of a large part of the process of construction to plants specialized in prefabrication. Even so, there are some problems related to the reduction of certain manual workstations that characterize the traditional construction system, so fewer employment opportunities will be created especially for the staff working on construction sites.

Table 9. The Practical Relationships between Lean Construction Tools and Sustainable Development Prefabrication

VSM

Poka Yoke

5S and visual Management

+

+

+

+

+

+

+

+

±

+

+

+

+

Productivity & Respect of the triptych (cost, quality, time)

+

+

Flexibility

+

Reactivity

+

Innovation / R&D

+

+

Customer satisfaction

+

+

Environment Resources consumption (materials, water, energy...) Pollution Prevention Emission of greenhouse gases Solid waste treatment

5. Conclusion The construction industry represents an integral part that contributes tangibly to the strengthening of the national economy and the reduction of unemployment. Nevertheless, this sector is considered among the main sources of greenhouse gas emissions and solid waste generation. Thus, it is one of the largest consumers of natural resources. Lean Construction is a way to design production systems in order to generate the maximum value for the customer by reducing the waste of materials, time, and efforts. It is a new concept which can bring revolutionary changes and great benefits to the construction industry. In this study, the practical relationships between lean construction tools and sustainable have been extensively explored. It has been established that the LC tools (Prefabrication, Value Stream Mapping, PokaYoke, visual Management &5S have a direct impact in promoting the main factors of sustainable development. Indeed, we have demonstrated that Lean Construction not only contributes to creating the economic value to the construction process but can also contribute to promoting the environmental and social issues. This philosophy represents a strong conceptual basis to achieve the objectives of sustainability. More empirical studies should be conducted in the future to quantify the influence of LC practices on the sustainable construction.

+

Economy +

+

+

+

+

+

+

+

Society Working conditions & Safety Employee involvement / Human resource development Employment

+

+

±

+

Acknowledgement The authors acknowledge the Laboratory of Industrial Techniques, Faculty of Sciences and Techniques of Fez-Morocco, for the provision of research facilities -This work has been supported by CNRST cooperation

This is an Open Access article distributed under the terms of the Tab. 9 shows the practical relationships between the Creative Commons Attribution Licence studied LC tools and the three dimensions of sustainable development (environment, economy, society). Generally, we can notice that most of these tools generate positive impacts on the majority of the issues of sustainable development, except for the prefabrication which could have ______________________________ References 1 2. 3.



Principaux Indicateurs du Secteur du Bâtiment et des Travaux Publics, Ministry of the habitat and city Policy. (2015) 2 p. Tableau de bord sectoriel, Ministry of economy and finance. (2015) 88 p. S. W. Whang and S. Kim, Energy Build. 96 76 (2015).

4. 5.

176

A.A.E. Othman, M.A. Ghaly, and N. Zainul Abidin, Manag. Constr. An Int. J. 6 917 (2014). H. Challot , BTP: 9 millions de tonnes de déchets déversées chaque année dans la nature

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APPLICATION OF LEAN CONCEPTS IN THE CONSTRUCTION INDUSTRY Madushan S.T.K, Hathurusinghe H.D.D.C, P.B.G.Dissanayake Department of Civil Engineering, University of Peradeniya, Peradeniya 20400, Sri Lanka

Abstract: Sri Lanka is a developing country experiencing a huge construction boom. All construction use various types of resources and waste of resources occur at all construction sites. These wastes include not only material resources but also labour, equipment, time, space, etc. The basic idea of lean is to create more value for the customer with fewer resources. Lean construction projects are easier to manage, safer, complete sooner and cost less and the end product is of better quality. The aim of this study is to understand the level of awareness on lean concepts in the construction industry of Sri Lanka, identify the wastes and classify using lean concept, identify barriers and difficulties that may be encountered in the implementation of lean concepts and propose effective and efficient means of lean construction management techniques to be adopted by the Sri Lankan construction industry. Keywords: Lean, Construction, Waste minimization 1. Introduction The simple idea of lean is creating more value for customers with fewer resources. Reducing waste along entire value streams, less capital, and less time, creates processes that need less human effort, less space, to make products and services at far less costs and with much fewer defects, compared with traditional business systems. Companies are able to respond to changing customer desires with a wide variety, high quality, low cost, and with a short period. Also, information management becomes more accurate and much simpler (Gilbert, 2008). Lean principles were originally derived from the Japanese auto industry, the Toyota Corporation. Lean Construction is a combination of operational research and practical development in design and construction with an adaption of lean manufacturing principles and construction process. Unlike manufacturing, construction is a project based-production process. (Remon, 2013). In the past several decades, the manufacturing industry changes with some technical and managerial levels. Once being the symbol of industrialization and development, the construction industry has been increasingly criticized for remaining

“backward” and being static parallel to the changes in the manufacturing industry. Coupled with various environmental dynamics, these criticisms have been turning into searches for a suitable improvement framework for the construction industry. (Low, 2013) The construction industry has wasteful practices and struggles to satisfy the parties involved. It is also an important and fundamental industry that its shortcomings create huge baneful effects. The people, who strive for a better construction context, set their eyes on the manufacturing industry. One of the revolutionary practices, rooted from the car manufacturing industry is lean production. Just after the 2nd World War, lean production helped the Japanese car manufacturers to compete against their Western competitors and spread rapidly in other countries. These days most of the companies are trying to apply the lean manufacturing methodologies/tools for their companies. There are many books, papers, societies, technical reports about lean production (Koskela, 1992). From the early 1990s, lean production techniques have been adopted by the researchers in the construction industry and the name “Lean Construction” originated from “Lean Production”. Especially via the

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universities located in the American continent and Northern Europe, lean construction is developing and lean practices are diffusing into the construction industry. Lean concepts suggest to construction industry to change their conventional management in to both flow and value management projects (Koskela, 1992). It also attempt to adapt the practical tools/ methodologies of lean production to the construction industry. Unlike other countries the Sri Lankan construction industry is yet to adopt lean construction management techniques. The main focus of this study is on the implementation of lean concepts and to analyse and propose effective and efficient means of lean construction management techniques to Sri Lankan construction industry. 1.1 Research objectives 1. What percentage of leading contractors is aware of lean construction techniques? 2. What extent has lean construction been accepted into practice by the construction industry 3. Identify the wastes sources classified under lean construction industry. 4. Study, analyse and propose effective and efficient means to improve lean construction management techniques to Sri Lankan construction industry. 2.0 Literature review 2.1 Beginning of the Lean Concept After the end of the Second World War Taiichi Ohno an engineer in the Toyoda Spinning and Weaving Corporation was called to the automotive side of the company. He was asked to improve operational productivity and drive in concepts of Just-In-Time and Jidoka. He was appointed as the machine shop manager of an engine plant and had to experiment many concepts in production in middle 90s. His work and effort was resulted in what is now achieved in the Toyota Production System. There are other people inside the company who contributed to the overall development of the Toyota Company and

its production system. The concept of Jidoka was the very first part of Toyota production system and it was created in 1902 by Toyoda founder. After that they were created a number of other tools and new ways, such as seven Wastes and eliminated techniques, kaizen, Andon, 5S, Error proofing, etc. (Meier, 2008). 2.2 Lean manufacturing The idea behind lean manufacturing is to enhance the value of the customer mean while eliminating the waste. Lean manufacturing lead the company to achieve high performance by generating more value using minimum resources. Waste is a nonvalue adding activity for a company. By reducing and eliminating waste in the manufacturing process, organizations could focus more on processes that need minimum human participation, minimum floor area and minimize lead times high quality manufacturing with a significant low cost than the traditional manufacturing. (Nilmini Thilakarathna, 2012). 2.3 Applying lean concepts in construction industry As a result of Lean construction, a new form of production management system came in to construction. Essential features of lean construction include a clear set of objectives for the delivery process, aimed at maximizing performance for the customer at the project level, construction, and the application of project control throughout the life cycle of the project from design to delivery. The lean concept has emerged and has been successfully applied to complex and simple construction projects. In general, lean construction projects are safer, easier to manage, completed on time and cost effective and are of better quality. This research discussed the implementation phases of lean construction showing the waste in construction and how it could be minimized (Remon, 2013) Projects are not permanent production systems, they are temporary production system. Therefore those systems are planned to complete the product while maximizing value and minimizing waste.

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Lean project management differs from traditional project management (Senaratne, n.d.). 3.0 Methodology The research methodology was used to achieve the objectives of the project. Basically we can identify the following steps. 3.1 Sample selection The method of the data collection for the project was through a questionnaire survey. The questionnaire was distributed among construction industry professionals working in the building construction industry. 3.2 The survey Survey questionnaire was divided in to three sections. The first, section was titled “Questions regarding the experience and the about company” The second section of survey was titled “Questions regarding the waste management of sites” These questions attempted to find out whether the company had proper management system to eliminate the waste and identified whether they use lean principle or any another method. The final section of this survey titled “Questionnaire regarding lean concept in construction industry”. The questions attempted to find barriers to implementing lean concept in construction industry in Sri Lanka, suggestion for implementing Lean concept and get an idea about their knowledge on lean principles.

The survey included eight types of wastes. The total outcome of this study was to find out whether the above mention wastes did occur at construction sites and whether there was a conventional procedure in eliminating those wastes. The questionnaire survey was focused on comparing evaluating merits and demerits of comparing conventional and lean construction management concepts. The survey was also used to analyse for possible barriers and difficulties in implementing Lean concept in construction industry in Sri Lanka. The questionnaire results were ranked according to Likert scale. The rank results were analysed according to the mean value calculation using equation 3.4.1. Mean value =∑ (ni×xi) ∕ ∑ni

equ (3.4.1)

xi= Likert scale for item, where I = 1,2,3,4,5 n = frequency of item 4.0 Results and Discussion Extracted information from questionnaires and direct interview can be present as follows. Survey questionnaire was designed in three sections. The first section included questions regarding the experience and background of the respondent and his company. This section helps to get an idea about responder’s position in this field. 4.1 Type of the company in responder work

The questionnaire survey was carried out using three methods. The questionnaire form was distributed among construction industry professionals by hand and via email. Face to face interviews were conducted with selected project managers, site managers and site engineers on a several projects. 3.3Analysis of responses

Fig 4.1 Type of the company in responder work

After the survey responses were received, analytical examination was carried out.

According to above result most of responders work as a contractor. Less number of persons works as a client.

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4.2 Position of the responder

Table 4.1 Analysis results of the difficulties in implementing of waste minimization Mean value

Fig 4.2 Position of the responder Working experience in construction industry responders experience was most effecting factor when doing this kind of survey. Therefore in this questionnaire form responder’s experience was categorized as follow. 1. <5 years 35 2. 5-10 years 17 3. 10-15 years 3 4. >15 years 2

Lack of promotion of waste minimisation extent Low financial incentive Expectations from client Competitive market Complicated sub-contraction system Lack of training awareness Lack of effective management tools Change of culture and behaviour

Rank

3.877

4

3.456

7

2.964

8

3.714

5

3.56

6

4.316

1

4.192

3

4.246

2

Fig 4.3 Working experience in construction industry The second section of survey included questions regarding the waste management of sites.

Fig 4.5 Responder’s familiarity with the word “lean construction”

Fig 4.4 Wastes in the construction sites

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Table 4.2 Analysis results of the effective ways to improve the construction waste management plan Mean value

Rank

4.263

1

construction techniques in the construction industry from 

It’s better to introduce new legislation related to lean construction for Sri Lankan construction industry.



Attitude is the most important factor for in this industry



Improving waste management process does not result in extra consume extra cost but it will improve the quality of a particular activity which will ultimately help to increase quality and minimize the rework



Client consultant and Contractor need to work more closely when applying this concept for a project. Basically client needs to pay attention to lean construction from the beginning for example in the preparation of the specifications and other requirements. Consultant need to include the facts of the concepts in their checklists and must monitor regularly, the contractor need to include the facts related to Lean concepts in their methods statements etc.



Lean concept is already use for some extent in precast fabrication to innovate and implement new trends to the industry.



Need to arrange a system for removing waste from site as beneficial.



This is a good concept to be adopted in a third world developing country like Sri Lanka.



Proper planning prior to ordering of materials and careful handling are also important



Need awareness programme in advance

4.3 Comments and suggestion from the industry



People behavior is the major issue

From the google document and face to face interviews (with questionnaire) with some site Engineers, project managers, Residence Engineers, Quantity surveys and Planning Engineers. Implementing of lean



Most people don’t know the word “Lean Construction”.



People use another waste minimization technique.

Proper training and education Employ prefabricated building components Implementing contracts with subcontractors Apply information technology Top management support and commitment Appropriate site layout planning Recycle waste operation on-site

3.281

5

3.649

4

4.07

3

4.193

2

4.263

1

4.07

3

Table 4.3 Difficulties in implementing of Lean concepts in the construction industry Sri Lanka

Peoples and partner issues Managerial and organizational issues Lack of support issues Cultural and philosophy issues Government issues Procurement issues

Mean value

Rank

3.596

4

3.789

1

3.701

2

3.667

3

2.982

6

3.316

5

5.0 Conclusions

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

Identified the extent of difficulties in implementing lean concepts in the construction industry of Sri Lanka.



There should be a proper mechanism to educate the people about lean construction principles.



Communicate the benefits of lean construction through seminars & conferences to the construction industry practitioners.



Government should enact policies which appreciate effort by firms which adopt lean principles.

This should eventually percolate to the lower level of the construction field. References [1]

Koskela, L., 1992. Lean Production In Construction, finland: s.n.

[2]

Low Sui Pheng, T. H. F., 2013. Modern-day lean construction principles. pp. 523 - 541.

[3]

Remon Fayek Aziz *, S. M. H., (2013). Applying lean thinking in construction and performance. Alexandria Engineering Journal, p. 679–695.

International Journal of Sustainable Construction Engineering & Technology (ISSN: 2180-3242) Vol 4, No 2, 2013

A REVIEW OF LEAN CONCEPT AND ITS APPLICATION TO SUSTAINABLE CONSTRUCTION IN THE UK Oyedolapo Ekundayo Ogunbiyi*, Adebayo Akanbi oladapo and Jack Steven Goulding University of Central Lancashire, United Kingdom *Corresponding E-mail : [email protected] Received 18 June 2013; Revised 26 September 2013; Accepted 6 November 2013

Abstract The UK Government has recognised the importance of the construction industry in achieving the overall goals of sustainable development. Therefore the Government has put several policies and strategies in place to achieve a more sustainable construction. Sustainable construction is considered as the application of sustainable practices and sustainable development principles to the activities of the construction sector. Lean construction is a new production philosophy which has the potential of bringing innovative changes in the construction industry. The Lean principles focus on the minimisation of both material and process wastes which in turn contribute to sustainable construction in terms of energy consumption and improvement in health and safety etc. This study aims at exploring the concept of sustainable construction and examines how the lean approach can impact on the sustainability practices within the construction industry. The study uses literature review to achieve the stated aim. The findings revealed that the application of lean construction principle, tools and methods have direct contributions to the attainment of sustainable practices within the construction industry. However, the study postulates that the better understanding of lean concept, proper implementation and integration of lean and sustainability concepts are required for lean construction to contribute to sustainable construction. Keywords: Lean construction, Sustainable Construction, Sustainability

1.0

Introduction

The UK construction industry is noted for its economic contribution with an output worth over £100billion a year. It provides employment for over three million workers and accounts for eight per cent of gross added value [1]. Nonetheless, the construction industry is also noted for its poor safety record evident from high rate of accidents on construction sites leading to workers injury or loss of lives [2]. This suggests the reason why more attention is paid to the sector. However, there are other benefits to be gained from a more sustainable construction industry. The adoption of a sustainable approach was suggested to lead to important business benefits and address the shortcomings of the construction industry identified in the Rethinking Construction report. This reflects that becoming more sustainable could lead to efficiency, profit-orientated practice and achieving value for money, as it is about helping society and protecting the environment. There is a growing awareness as to the competitive advantages that can be convened by businesses taking a sustainable approach [3]. Lean construction is a new production philosophy which has the potential of bringing innovative changes in the construction industry. The concepts and principles of lean is to generally make the construction process leaner by removal of waste which is regarded as nonvalue generating activities [4]. The removal of waste (process and material) and value generation in terms of adding value to the customer are the major contributions of lean construction to sustainable development [5]. This is achieved by the use of lean principles: pull system, flow, value stream mapping, continuous improvement and involvement of employees. There are several key factors to be taken into action by the construction industry. These factors have been suggested by the UK Government in its strategy for more sustainable construction [6]. These factors include: Published by:Universiti Tun Hussein Onn Malaysia (UTHM) and Concrete Society of Malaysia (CSM) http://penerbit.uthm.edu.my/ojs/index.php/IJSCET

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1. 2. 3. 4. 5. 6. 7. 8. 9.

Design for minimum waste Aim for lean construction Minimum energy in construction and use Pollution reduction Preservation and enhancement of biodiversity Conservation of water resources Respect for people and local environment Setting targets Monitoring and reporting in order to benchmark the performance

Among several factors, the lean construction principles will be focused on, as the main area of this study is to critically review the concept of Sustainable Construction (SC), and examine how the application of lean principles can impact on the sustainability practices within the construction industry. Accordingly, this study pulls from two main bodies of literature: i.e. the literature on sustainable development and lean construction in the broader context of the construction industry (see Figure 1). As earlier mentioned, the construction industry is considered as a key sector for achieving sustainable development goals because it plays a vital role in the drive to promote sustainable growth and development.

Construction Industry

Lean Construction

Sustainable Construction

Figure 1: Literature review focus The potential of lean to contribute to sustainable construction has been raised for discussion [5]. Therefore, it is of utmost importance to examine the possibilities of lean contributing to sustainable construction. Several studies have been carried out on lean and its application within construction at project level with great benefits achieved and there are many studies that have investigated lean construction and sustainability separately [7, 8]. However, studies that highlight the contributions of lean construction towards sustainability are few. The insufficiency of literature addressing this issue and the absence of research-based papers are assumed as a lack of awareness of the potential of lean construction as a means of achieving sustainability and an unrecognised relationship between sustainability and lean construction objectives. For instance, Forbes et al.[9] proposed a framework for providing technical support for lean methods application in some environments in developing countries. Sacks et al. [2] developed a research framework for analysis of the interaction between lean and BIM. However, there has been little or no study done to look at the impact of lean on sustainable construction in terms of developing a framework at the organisational level. Against this background, this study aims to examine the contributions of the implementation of the lean approach in sustainable construction.

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2.0

Sustainable Construction

It is difficult to describe sustainable construction without defining or describing sustainable development. There are several definitions of sustainable development given in the literature [10, 11]. Sustainable development is a broad concept which has been adopted and interpreted in numerous contexts. For example many authors have seen the concept as vague and fuzzy [12, 13]. According to Sage [14], sustainable development refers to the fulfilment of human needs through simultaneous socio-economic and technological progress and conservation of the earth's natural systems. However, the most popular definition of sustainable development is the one given in the Brundant report “development that meets the needs of the present without compromising that ability of future generations to meet their own needs” [15]. Nevertheless, there are some areas of agreement in the various definitions. This reflects that the goal of sustainable development is to enable humanity all over the world to satisfy their basic needs and enjoy a better quality of life without compromising the quality of life of future generations. The concept of sustainable development has been described with three dimensions: economic, social and environmental aspect. Sustainable development and social responsibility have become increasingly important strategic issues for companies in virtually every industry [16]. The term sustainable construction means different things to different people as there are multiple definitions, and variance in terms of scope and context as well as practices [11, 12, 17]. Bourdeau et al. [17] stated that sustainable construction practices are widely different depending on how the concept of sustainable construction is developed in various countries. Therefore, simply put, sustainable construction is the response of the building sector to the challenge of sustainable development [5]. The implementation of sustainable construction is still under explored. The decision making process and the actors as well as the inter-relationship has to be understood when implementing sustainable construction [18]. The issues of sustainable construction are divided into 3 aspects: the environmental, economic and the social issues. CIEF [19] suggests sustainable construction as a solution for significant cost savings, to bring innovations and to enhance competitiveness for long time survival of any organisation. Sustainable construction practices not only provides increased market share and profitability but also brings many other intangible benefits such as visible brand name to the organisation in the industry, quality in construction, employee motivation and satisfaction, improved customer’s satisfaction, and complements / awards from regulatory authorities and improved shareholder relations [19, 20].

3.0

Lean Thinking in Construction: Lean Construction

The application of lean thinking in construction was pioneered by Koskela who suggested that construction production should be seen as a combination of conversion and flow processes for waste removal. The concept of lean is attributed to the manufacturing industry and was introduced to construction [4].The use of lean concept has been advocated in the UK, several seminars and initiatives have been undertaken in an effort to encourage its uptake. The Construction Industry Research and Information Association (CIRIA), Construction Productivity Network (CPN), Construction Lean Improvement Programme (CLIP) and the Lean Construction Institute UK (LCI-UK) are some of the examples of institutions established. Seminars and conferences have been organised to tease out the main issues in the development and awareness of lean construction principles with real life case studies of some construction organizations presented [19]. In spite of these efforts, there seems to be some barriers to the successful implementation of lean construction. Generally the rate of lean implementation within the UK construction industry is relatively low and the application of lean in sustainable construction is still under explored [21]. Some studies have identified the barriers to the implementation of lean construction. These barriers need to be overcome in order for construction industry to reap the benefits of implementing lean construction. The application of lean principle to construction has

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been presented to result in benefits such as improved quality, improved safety, waste reduction, increased productivity, more client satisfaction, increased reliability, and improvements in design. A study carried out by Sarhan and Fox [22] reveals that there seems to be positive trends in the development of a lean culture among UK construction organisations. Lack of understanding of how to successfully apply lean thinking principles to specific construction processes was also revealed. This study of lean culture within the UK construction organisations was carried out after the study of Common et al., and Johansen and Walter [22]. Lean thinking has become an important concept within the UK construction industry following the Egans report. There has been significant improvement in the agenda for change in the UK construction industry. Few studies have been carried out in order to establish the current levels of awareness and implementation of lean thinking within the UK construction industry. An example of such studies is the application of the Last Planner into a UK construction project. Last Planner is one of the lean tools and techniques and perhaps the most developed tool. The tool was applied to a UK construction project to ascertain its value and its possible barriers. However, the study raised a number of important structural and cultural problems for the success of Last Planner in the UK [23]. Shah and Ward [24] pointed out that it is essential to differentiate between those studies considering lean from a philosophical perspective related to guiding principles or overarching goals, and those analysing the concept from a practical perspective as a set of management practices, tools, or techniques that can be observed directly. The implementation of lean construction have been targeted towards some specific tools and principles without a full integration on different aspects such as supply chain, safety, planning and control, production design and management, culture and human aspects [25-27]. Framing an encompassing definition that covers all aspects of lean is seen as a difficult task [28]. Alves et al., [26] stated that there are many meaning of lean when applied to construction. Therefore, this study deems it fit to scrutinize various definition of lean as applied to construction. Table 1 presents various definition of lean. Lean offers significant benefits in terms of waste reduction and increased organisational and supply chain communication and integration. The elimination of waste leads to cost benefits advantage, however these are pre-requisite for creating a lean process. The lean implementation effort stage one focus on waste elimination from a technical and operational perspective [29]. Process Mapping, Value Stream Mapping, and 5S (Workplace Organisation) are some of the tools for achieving such processes. There are 7 types of waste identified under lean: overproduction, overstocking, excessive motion, waiting time, delay and transportation, extra-processing, defect and rework. In the same manner, there are various methodologies for attaining lean production: just in time (JIT), total quality management, concurrent engineering, process redesign, value based management, total productive maintenance and employee involvement. Table 1: Definitions of Lean

Sources

Definition

Manrodt[30]

Lean is a systematic approach to enhancing value to the customer by identifying and eliminating waste (of time, effort and materials) through continuous improvement, by flowing the product at the pull of the customer, in pursuit of perfection

Ballard et al. [31]

Lean is “a fundamental business philosophy – one that is most effective when shared throughout the value stream”

Lean Construction Lean construction is a production management-based project Institute [32] delivery system emphasising the reliable and speedy delivery of Published by:Universiti Tun Hussein Onn Malaysia (UTHM) and Concrete Society of Malaysia (CSM) http://penerbit.uthm.edu.my/ojs/index.php/IJSCET

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value

Radnoret al. [33]

Lean is a philosophy that uses tools and techniques to create a change of organisational culture in order to implement the ‘good practice of process/operations improvement that allows the reduction of waste, improvement of flow, more focus on the needs of customers and which takes a process view’

Construction “The continuous process of eliminating waste, meeting or exceeding Industry Institute all customer requirements, focusing on the entire value stream and [34] pursuing perfection in the execution of a constructed project.” Shah [24]

3.1

and

Ward ‘‘an integrated socio-technical system whose main objective is to eliminate waste by concurrently reducing or minimising supplier, customer, and internal variability.’’

Lean Approach in Sustainable Construction

Lean construction is one of the strategies for improving the sustainability of construction, in other words one method of achieving sustainable construction. Lean approach in sustainable construction focuses on the removal of all forms of wastes from construction processes to allow more efficiency. Existing studies have suggested theories to support that lean is a method for optimising resources, improving safety, productivity, working condition and overall, the social, environmental and the economic bottom line [35]. There are several forms of waste under the lean terminology: processes, material and poor safety are considered as a potential wastes that hinder flow of value to the client. Construction should be seen as flow processes (consisting of both waste and conversion activities), not just conversion processes [4]. The promotion of health and safety practice can contribute to sustainable construction by enhancing workers’ social life and minimising direct and indirect cost of accidents. Material waste elimination has been identified as the most efficient and cost effective approach to promote sustainable practice on construction sites. Similarly, the principles of lean construction focus on creating a sustainable change by stressing on efficient, waste-free and safe flow, storage and handling of materials to minimise cost, energy and resource consumption, and provide value for clients and end users [7]. Some of the key issues of sustainability identified in the literature include: global warming and climate change which is seen as one of the main threats to the environment as a whole [36]. Peng and Pheng [37], investigated the contribution of the lean concept to achieve low carbon installation in the construction sites using precast concrete products and found that the lean concept can be adopted to reduce carbon emission in terms of re-designing the site layout, improving the supply chain and installation work flow. Many studies have highlighted the contributions of lean construction towards the environmental aspect of sustainability. For example Huovila and Koskela [5] presented minimisation of resource depletion, pollution and matching business and environmental improvement as the contribution of lean construction to sustainable development. However, the contribution of lean construction to sustainable development is not limited to the environmental aspect but also to the social and economic aspect. The different lean applications might have different results on the three pillars of sustainable development. The lean impact has been described to cover the economic, social and environmental aspect of sustainable construction. This include more value to client with less waste of time and resources, process improvement and overall project delivery, productivity improvement, cost reduction, improved quality and safety as well as promotion of continuous improvement. A good example of this is the case study of the modular home building by Nahmens [29] which was Published by:Universiti Tun Hussein Onn Malaysia (UTHM) and Concrete Society of Malaysia (CSM) http://penerbit.uthm.edu.my/ojs/index.php/IJSCET

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carried out to evaluate the use of lean construction to improve sustainability. Lean construction strategies serves as a platform for improvement in the delivery of the sustainable modular houses. Figure 2 presents the main effect of the application of the lean concept for the purpose of sustainability in the aforementioned example.

Figure 1: Conceptual model: effect of lean on sustainability Source: (Nahmens and Ikuma, 2009)

As much as adopting lean concept has been attributed to positive influence on sustainable construction in terms of improved safety, many research works have shown both negative and positive effects of lean on safety. However, in terms of sustainability, lean and safety influence economic sustainability by reducing costs and increasing productivity, environmental sustainability by reducing or improving materials and social sustainability by affecting the wellbeing of workers.

3.2

Sustainable Practice and lean concept

According to Tan et al., [38], Sustainable construction practices include five major areas: compliance with sustainability legislation, design and procurement; technology and innovation; organisational structure and process; education and training; and measurement and reporting. The successful implementation of lean and sustainable concepts by an organisation depends on the level of commitment and knowledge. The implementation of sustainability throughout the organisation including the organisation’s project will yield more result than when implemented only on the project [39]. Different company characteristics can influence the choices in sustainable construction practices. The selected sustainable construction practices should be consistent with the overarching strategy. The benefits of implementing sustainable practices include improved regulatory compliance requirements; reduction of liability and risk; enhanced reliability among customers and peers; reduction of harmful impacts to the environment; prevention of pollution and waste (which can result in cost reduction); improvements in site and project safety (by minimising injuries related to environmental spills, releases and emissions); improved relationships with stakeholders such as government agencies, community groups, and clients [40]. The benefits of implementing sustainable practices in construction can be grouped under environmental, economic and social aspects. Hall and Purchase [41] stated that numerous Published by:Universiti Tun Hussein Onn Malaysia (UTHM) and Concrete Society of Malaysia (CSM) http://penerbit.uthm.edu.my/ojs/index.php/IJSCET

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sustainability and lean practices, such as productivity, safety, efficiency, and waste minimisation, are interconnected. The conceptual relationship between lean and sustainability has been presented in the literature. Lean practices can be adopted in a construction project at design phase to reduce costs and enhance sustainability [42, 43]. Few studies have been carried out to investigate the application of sustainability and lean concept. Despite the pressure on the construction industry to adopt the concept of sustainability to improve the current unsustainable pattern of project delivery, its uptake is relatively slow i.e. the adoption of sustainable practice in construction project. Koranda et al., [8] developed a framework for implementing lean techniques and sustainability in a construction project as shown in figure 3. This framework captured the major sustainability issues at project level.

Figure 3: Framework for implementing lean techniques and sustainability in a construction project (Source: Koranda et al. 2012) There is need for leadership participation in the quest for attaining a more sustainable construction as the leadership role in construction organisation is one of the paramount factors that can provide an overall vision, direction and vision towards the attainment of a sustainable construction. Therefore, it is highly essential that leaders have full knowledge of the concept of sustainability to be able to guide their organisations effectively [44]. Likewise, top level leadership commitment has been identified as one of the success factors for the implementation of Published by:Universiti Tun Hussein Onn Malaysia (UTHM) and Concrete Society of Malaysia (CSM) http://penerbit.uthm.edu.my/ojs/index.php/IJSCET

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lean. This suggests that thorough understanding of lean and sustainability concepts as well as principles are necessary for proper application on a construction project.

3.3

Lean Tools and Methodologies for Sustainable Construction

Various lean tools and techniques for enabling sustainability have been discussed by several authors. Some studies have explored various issues of sustainability by means of lean initiatives and established the benefits that can be derived by applying the lean principles/tools [42, 45]. Lean design methods such as Integrated Design, Design for Maintainability (DFM), Setbased Design, Target Costing and 3D Modelling can be used during the construction of sustainable project. Many studies have suggested integrated design method to be one of the most critical methods for sustainable construction [46-48]. Just-in-time (JIT) is a major component of the lean construction concept, the principle of just in time is to ensure that the correct quantities of materials are delivered as at when needed in the right quantity to the exact location in good condition [49-51]. Bae and Kim [43] carried out the quantitative assessment of lean methods and sustainability impacts of construction project. This was based on the lean project delivery phases which include: lean project definition, lean design, lean supply, lean assembly and whole delivery process. It was revealed that most lean construction methods provide positive economic impacts for sustainable projects while there are few negative impact as well as the combination of both impact (positive and negative) on the social and the environmental aspects. There are many lean tools and techniques/principles among which 5S, value stream mapping, just in time, visualisation tool, last planner, value analysis, pull approach and continuous improvement appears to be the commonly adopted lean tools and techniques/principles [45]. Value stream mapping (VSM) is the mapping of wastes throughout the organisation. 5S and value stream mapping are commonly noted for environmental improvement. 5S helps companies to look at their workplace in a new dimension. Companies use 5S to clean and streamline areas within their works, removing unwanted parts, tools and general debris and setting a new standard for cleanliness and tidiness. It also helps in organising construction site, thereby resulting to environmental improvement and health and safety improvement.

4.0

Conclusions

The study has drawn from literature on both lean and sustainability reflecting the principles of lean and how it impacts on sustainable construction. Better understanding of lean concepts by the construction industry can contribute to improvement in all aspect of sustainable construction. The concept of lean and sustainable construction both seeks to minimise waste, but this is achieved through different approaches. There is need for construction stakeholders to set their priorities before the start of a project for better integration of the two concepts. More emphasis should be laid on lean approach in sustainable construction framework. There should be more level of commitment and knowledge by an organisation in order to successfully implement and derive maximum benefits from the concept of lean and sustainability. However, the application of lean in sustainable construction is not only possible on the operational level; it could also be applied at the strategic level. Therefore, this study will go on to further present the application of lean and sustainability at the strategic level and also explore the benefits that can be achieved.

References [1] Construction Industry Research and Information Association CIRIA, “Guide to sustainable procurement in construction. London” Construction Industry Research and Information Association C695, 2011. [2] R. Sacks, B. Dave, L. J. Koskela, and R. L. Owen, “Analysis framework for the interaction between lean construction and building information modeling,” Proceedings of the 17th annual conference of International Group for lean Construction, 2009. Published by:Universiti Tun Hussein Onn Malaysia (UTHM) and Concrete Society of Malaysia (CSM) http://penerbit.uthm.edu.my/ojs/index.php/IJSCET

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KSCE Journal of Civil Engineering (2012) 16(5):699-707 DOI 10.1007/s12205-012-1460-5

Environmental Engineering

www.springer.com/12205

An Investigation of the Applicability of Sustainability and Lean Concepts to Small Construction Projects Collin Koranda*, Wai Kiong Chong**, Changwan Kim***, Jui-Sheng Chou****, and Changmin Kim**** Received January 20, 2011/Accepted September 13, 2011

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Abstract Sustainability and lean concepts can both be applied to the construction industry to help minimize waste. Although both concepts work to alleviate similar problems, organizations struggle to integrate the concepts. This paper examined projects of different sizes and in different environments within the Midwestern United States to determine what aspects hinder the integration of sustainability and lean concepts within the region. Professionals associated with the industry were interviewed to identify sources of waste for lean and sustainable projects. From the case studies, various aspects of waste that exist in construction projects were recognized, and a comparison of the interaction of lean and sustainable concepts was documented. A process for planning throughout the entire construction process was determined so that waste can be reduced and the integration of lean and sustainable concepts is more achievable. Keywords: lean, sustainability, LEED, sustainable construction, lean construction ···································································································································································································································

1. Introduction The World Commission on Environment and Development's report (World Commission on Environment and Development, 1987) outlined the concepts of sustainable development and has become the foundation for sustainable construction. The objective of sustainable development can be summarized as, “development that meets the needs of the present without compromising the ability of future generations to meet their own needs.” The sustainable development concept has expanded to encompass the sustainable construction concept, which is more technically oriented and includes methods to improve energy efficiency, reduce life cycle cost, and enhance the environmental responsibility of existing buildings. Kibert (1994) defined the six key principles of sustainable construction as: 1) minimization of resource consumption, 2) maximization of resource reuse, 3) use of renewable or recyclable resources, 4) protection of the natural environment, 5) creation of a healthy, non-toxic environment, and 6) pursuit of quality in creating a built environment for sustainable construction. The Leadership in Energy and Environmental Design (LEED) Green Building Rating System is one of the

premier green building programs in the USA and has become the international accepted benchmark (Huang and Hsu, 2010; US Green Building Council, 2011). LEED follows a scorecard methodology with four levels of certification for the completion of various tasks in the categories of Sustainable Sites, Water Efficiency, Energy & Atmosphere, Materials & Resources, and Indoor Environmental Quality (U.S. Green Building Council, 2011). Although green building standards are not the only facet of sustainable construction, their relationships are extremely close. The concept of lean construction is similar to that of sustainable construction in that both concepts seek to minimize waste during construction. Lean construction is a constantly evolving concept that rejuvenates the effectiveness of the construction process. The concept of lean is to identify, reduce or, wherever possible, completely eliminate waste from the production process (Wang et al., 2009; Lonngren et al., 2010). Just-In-Time (JIT) is a major component of the lean construction concept (Mao and Zhang, 2008; Eriksson, 2010) the objective of which is to ensure that the correct quantities of materials are delivered to the exact location in good condition at the time when the material is needed (Low and Choong, 2001; Birdi et al., 2008).

*Construction Engineer, Black & Veatch Corporation, Kansas City, MO, 64114, USA (E-mail: [email protected]) **Associate Professor, Dept. of Civil, Environmental and Architectural Engineering, University of Kansas, Lawrence, KS 66045, USA (Corresponding Author, E-mail: [email protected]) ***Member, Associate Professor, Dept. of Architectural Engineering, Chung-Ang University, Seoul 156-756, Korea (E-mail: [email protected]) ****Professor, Dept. of Construction Engineering, National Taiwan University of Science and Technology, Taipei, 106, Taiwan, R.O.C. (E-mail: jschou@ mail.ntust.edu.tw) *****Graduate Research Assistant, Dept. of Architectural Engineering, Chung-Ang University, Seoul 156-756, Korea (E-mail: [email protected]) − 699 −

Collin Koranda, Wai Kiong Chong, Changwan Kim, Jui-Sheng Chou, and Changmin Kim

The fundamental difference between lean manufacturing and lean construction lies in production line assembly. In manufacturing, products move along the conveyor system while the equipment stays stationary; as a result, correction of a defect within the production system will eliminate any defect from the following products. The construction process, by contrast, requires equipment to be moved in order to produce a product. As such, the benefit from eliminating a defect from the production system cannot easily be repeated in another location. Thus, the construction industry’s most common approach to eliminating defect is to rework. As lean construction continues to evolve, some identifiable features have emerged. Howell (1999) suggested that the fundamental concepts of lean construction should include: (1) identifying and delivering value, (2) organizing production into a continuous flow process, (3) perfecting products and increasing flow reliability by integrating inventory management, information distribution, and decision making, and (4) continuously improving the products and processes. Commitment and knowledge are the keys to the successful implementation of lean and sustainable concepts. Research has shown that an organization will benefit more from sustainability implementation if it exists throughout the organization rather than only in their projects (Beheiry et al., 2006). Many lean and sustainability practices, such as safety, efficiency, productivity, and waste minimization, are interconnected (Hall and Purchase, 2006). As such, Pulaski et al. (2006) identified the principles for combining sustainability and constructability at the design and construction stages, such as simple construction details and the use of structural elements as finishing materials. The Pentagon and Toyota South Campus are two case studies that thoroughly examined the integration between sustainability and lean concepts. Study of the Pentagon renovation project showed that the integration of sustainability and lean concepts saved both money and time. The Toyota South Campus project in Torrance, CA demonstrated a strong relationship between sustainability and lean concepts (Lapinski et al., 2006). Lapinski et al. (2006) explained that the lessons learned from the Toyota project included: (1) early evaluation and adoption of environmental considerations, (2) business case imperatives, (3) sustainable compatibility, (4) early selection of team members with sustainable

experience, and (5) alignment of team member and project goals. Lapinski et al. (2006) also noted that the processes used in Toyota’s delivery method are very similar to LEED approaches, and that Toyota could achieve higher standards without going through LEED certification. Though both projects are excellent examples of the success of integrating lean and sustainable concepts, not every organization has the resources and knowledge of Toyota or the Department of Defense. Most projects have limited resources to implement and limited knowledge of the concepts of lean and sustainable. The purpose of this study is to investigate the relationships among worksite, design, the environment, and sustainability and lean concepts from a perspective of small construction projects. This paper also examines the current state of application of sustainability and lean practices on these projects and examines how such practices could potentially be mainstreamed. The other focuses of this research are to establish the relationships between sustinability and lean concepts and to develop a framework in which small projects can integrate and implement both practices. In this study, information was collected from six small and medium-sized construction projects in the Midwestern United States and from 35 architects, engineers, and contractors. These projects represent the kinds of projects that are commonly performed in the region: a mix of small- and large-sized projects, as well as LEED and non-LEED projects. The conditions for each project were unique and were representative of these types of projects. During data collection, many project managers were found to have unconsciously applied lean concepts (such as the reduction of on-site inventory). Descriptions and details of the projects are listed in Table 1.

2. Qualitative Analysis This study qualitatively analyzes information that was collected from 35 selected architects, engineers, and contractors who worked on the designs and construction of six lean and LEEDcertified projects. Interviews were conducted with the project managers of the involved general contracting firms and three subcontracting firms, as well as the architects and engineers. Phone interviews were also used to gather and verify information.

Table 1. Project Summaries of Preliminary Selected Projects Project A B C D E F Pentagon Toyota South Campus

LEED EnvironStorage Square Cost Certifiment Constraints Feet (Million) cation Rural No Minimal 62,000 $9.00 Suburban Yes Minimal 129,000 $30.00 Suburban Yes Minimal 178,000 $30.00 Urban No Very High 730,000 $114.00 Metropolitan No Very High 770,000 $200.00 Urban Yes High 1,200,000 $180.00 Urban Yes Unknown 6,600,000 $1,060.00 Urban

Yes

Unknown

640,000

$87.00

$145.16 $232.56 $168.54 $156.16 $259.74 $223.41 $160.61

Storage for Change order (H-Higher than other Delivery Recycled projects, E-Equal to other projects, Constraints materials L-Lower than other projects) No H No Yes L No Yes L No No H Yes No E Yes Yes E Yes Unknown ? Unknown

$135.90

Unknown

$/S.F

− 700 −

?

Unknown

KSCE Journal of Civil Engineering

An Investigation of the Applicability of Sustainability and Lean Concepts to Small Construction Projects

2.1 Impediments to Lean Concept Implementation and Complications with Sustainability Concepts The materials and systems used in a project pre-determine the constraints of the project. The materials and systems specified in these projects normally impact (1) the lead time of material and system delivery, (2) the reliability of shipments, (3) the delivery distance, (4) the reliability of source material, (5) the reliability and working relationships among the designers, contractors, subcontractors, and material suppliers, and (6) worker productivity. Certain green materials were available for JIT delivery, and their use generated more waste due to worker unfamiliarity with the materials. For example, Forest Stewardship Council (FSC)certified wood had to be delivered from an alternative source in many Midwest regions and tended to be less reliable. Moreover, bamboo flooring (a highly recyclable material) had to be shipped from China and Southeast Asia, thus demanding a longer lead time. Some materials became more “costly” as a result of the amount of waste incurred during installation, and contractors often combined both green and non-green materials to control project cost escalation and improve schedule reliability when implementing sustainable concepts. To minimize the impacts on delivery and reliability, contractors normally ordered sustainable materials in larger quantities and scheduled for longer lead times. Hence, a longer lead time for delivery and higher rates of allowable damage were normally permitted. The use of regional material may be the best way to achieve JIT delivery in lean concepts since the material for the project can be timely used without the need for stocking. Moreover, sustainable construction can be realized by avoiding longdistance shipments, thereby reducing carbon emissions for the project. However, the use of regional material is not always possible or desirable. Local suppliers may be unreliable because they have a relatively small-scale production system and a limited supply capacity. Thus, purchasing material from long-distance providers may be better to assure timely project completion. Designers had to consider how the materials affected the schedule and quality of their projects. Contractors normally used the least expensive materials from the most reliable sources, as long as they could meet the product specifications. 2.2 Contractual Arrangement, Design and Specifications Contractual arrangements were found to limit the interaction and thus the knowledge integration between designers and contractors. Communication between the designers and the contractors in a traditional project delivery method, a Design-Bid-Build (DBB), started much later since the owner separately contracts with the designer and contractor (Hwang et al., 2011). In the case of a Design-Build (DB), the owner contracts a DB firm early in the project development process; thus, communication between the designers and contractors occurs more frequently than in it does in DBB projects (Imbeah and Guikema, 2009). The feedback from the interviews highlighted that more changes during construction and relatively more waste were generated in DBB projects. The study also suggested that DB was the best contractual arrangement Vol. 16, No. 5 / July 2012

for lean and sustainable projects because it encouraged earlier communication and allowed for better knowledge integration between the designers and contractors. Earlier and more frequent communication helped integrate knowledge and information regarding, for example, regional conditions, materials, practices, and uncertainties. Such communication helped designers and contractors to align their project objectives and reduced designconstruction conflicts, which further facilitated the application of lean and sustainable concepts. 2.3 Knowledge, Design and Construction Integration Feedback from the designers and contractors stressed that knowledge of sustainability and lean concepts significantly affects the success of implementation. Unfortunately, most of the designers and contractors involved in the small projects were not knowledgeable in these areas. In addition, four of the six projects studied indicated a lack of alignment between design and site practices as the major cause of material waste. Designers of the small projects rarely communicated with the contractors when developing their designs. In addition, there were many small firms that did not have experience with sustainable or lean projects. Poor knowledge of the region was another important cause of waste. For example, the contractor for Project A tried to earn a recycled content credit by procuring and using flooring material that contained recycled content and then used it alongside other material that did not have any recycled content. As a result, the flooring installation was delayed because the lead time of the delivery was affected. It was nearly impossible for designers to integrate their designs and eliminate waste in a lean and sustainable manner if they did not know much about the region. The small and more commonly built projects faced more challenges than the large projects because they normally involved fewer management resources since each team was involved in several simultaneous projects. This case study shows that communication is vital to the success of a project. In Project B, which was LEED-certified, 85% of its waste was recycled because the project planners made special efforts to discuss ways to increase the amount of recycled waste. 2.4 Conflicting Priorities Conflicting priorities between designers and contractors were found to negatively affect the successful implementation of sustainability and lean concepts. Feedback from the contractors highlighted that they were more concerned with eliminating wasted time from idle laborers than with eliminating material waste. The designers, on the other hand, were more concerned with the performance of their designs and compliance with “quality” and “sustainability” requirements. The concepts of lean manufacturing do not separate the design from the production process and consider the designers and manufacturers as one entity; however, designers and contractors work independently in most construction projects. As a result, conflicting objectives and priorities often occur. Sustainability and lean concept implementation may be easier if stakeholders determine their

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priorities before the start of a project. 2.5 Uncertainties, Contingencies and Risks Another factor that reduced the efficacy of the implementation of sustainability and lean concepts was risk. For Project A, an additional 10% of concrete was ordered to ensure that all pours could be completed on time and to minimize labor downtime. Project managers often had to balance the impacts on project cost and schedule for pouring versus not pouring. Project D consisted of a concrete, ground-level parking garage for which the finishing on the concrete surface was not critical, so concrete pouring continued even during rain. In Project E, concrete was also poured in the rain but had to be refinished in areas that are visible to the public. A certain amount of waste was unavoidable, and thus, there was a need to examine the balance between risk and waste. Thus, the manner in which to balance those risks should be addressed in future research.

3. Quantitative Analysis This study analyzes quantitative information collected from six case studies. The survey included a set of 18 questions, and each question was broken down into the appropriate CSI MasterFormat divisions. This study attempts to quantify the relationships between various project variables and the implementation of lean and sustainable concepts. The variables are analyzed and presented in Table 2. 3.1 Relationships between Project Size and Sustainability and Lean Concepts Project size seems to have an impact on the need and ability to implement sustainability and lean concepts. Small projects needed relatively more storage space (by percentage) than did

the large projects. In addition, the small projects required smaller quantities of materials, which led to earlier material shipments. Because less equipment and fewer activities were involved at the work sites, more space was generally available for storage. The small projects involved more down time between activities because these projects were normally one of the contractor’s many projects. Many subcontractors moved between sites and did not dedicate much time to each site. Hence, materials had to be ordered and delivered for several projects at the same time, and the contractor could not dictate the exact time for delivery at any one specific site. The percentage of labor costs over the total project costs was higher for the small projects, and thus, it made sense for the contractors to concentrate on labor costs rather than material costs. In contrast, the larger scope of work for the large projects increased the material quantities needed, thereby making the need for lean concepts greater and more justifiable. 3.2 Relationship between Storage Space and Sustainability and Lean Concepts This study found that materials were stored on site for a shorter amount of time if there was less storage space because turnover was needed to make space for incoming materials. The increased amount of equipment and activities also constrained space availability. The two case studies with the highest storage constraints, Projects D and E, were located in urban and metropolitan environments, respectively. The average time that materials were kept on site was less than three days, and many materials were installed on the day of delivery. Projects D and E strived for JIT deliveries to reduce the amount of materials being stored. The projects located in urban environments did not have as many space constraints. The project manager thus preferred to have a truckload of material delivered at a time that would minimize defects and cost. The average storage time for Project

Table 2. Comparison of Small, Large, LEED and Non-LEED Projects Variable

Smaller Projects

Larger Projects

LEED Projects

Non-LEED Projects

Storage space availability (%) Higher Lower Higher Lower Total amount of equipment Less More No impact No impact Number of activities Fewer Higher Higher Lower Material variety Less More Higher Lower Labor costs (% of other cost) Higher Lower Slightly higher Slightly lower Management costs Lower Higher No impact No impact Priority for lean concepts in single projects Lower Higher Slightly higher Slightly lower Ability to integrate lean and green concepts Difficult Easier Not relevant Avg. lead time for larger items More Lower More Lower Avg. lead time for smaller items About the same Avg. time that materials stay on-site Lower Higher Higher Lower Quantities of materials delivered and installed the same day Higher Lower Lower Higher Justification of recycling and reusing for lean implementation Lower Higher About the same Impact of suitable materials on project Higher Lower Higher Lower Knowledge of lean concepts Slightly lower Slightly higher Slightly higher Slightly lower Knowledge of sustainability Slightly lower Slightly higher Higher Lower Change order (by percentage) compared to project cost Slightly lower Slightly higher Slightly lower Slightly higher * The benchmarks in the table are comparative and apply only to the six case studies. − 702 −

KSCE Journal of Civil Engineering

An Investigation of the Applicability of Sustainability and Lean Concepts to Small Construction Projects

F was about seven days, and the amount of materials being installed on the day of delivery was not as high as those in Projects D and E. More frequent on-site monitoring of materials is critical if a project implements the JIT concept. For Projects D and E, the quantities of materials on site had to be checked and balanced with the future demands. Hence, the project managers deliberately controlled the procurement process, material production, and offsite storage. However, for Project F, with fewer constraints, managers concentrated on monitoring the available spaces for storage rather than the quantities of materials. The construction sites with less storage space tended to have tighter restrictions for unloaded materials. Projects D and E had only two gates. Both of these projects were further constrained when materials had to be delivered on time. As a result, material delivery for these projects generally affected other activities. For instance, several activities had to be postponed to unload large materials such as structural steel. As another example, in Project D, some deliveries had to be returned when they arrived at the wrong time. This process was further complicated when multiple subcontractors had to coordinate their delivery schedule times. For some deliveries in Project D, a lane closure had to be requested from the city, further limiting the possible delivery times. In contrast, this problem did not occur with Project F. Projects A, B, and C had fewer limitations on storage space, and managers were able to order materials in larger quantities. However, in Project C, JIT techniques were attempted for structural steel, although the average storage time was still nearly five days. In addition, because they were working on multiple projects, the contractors for Projects A and B could not control the delivery times for all of their projects. Therefore, they had to save space for storing materials that had to be delivered earlier than they were needed. The longest storage time encountered for Project C was for the glass, which was on site two weeks earlier than it was needed. The project managers ordered the glass in a larger quantity to reduce the delivery cost. Project B was similar to C in that the managers tried to minimize the overall material storage time, although this was not a major focus. These projects only applied lean concepts if the project cost would be reduced. 3.3 Impacts of Recycling and Reuse on Sustainability and Lean Concepts The practices of recycling and reusing waste had a major impact on the projects. Projects F, C, and B diverted 50%, 75%, and 85% of the waste from landfills, respectively. However, additional space was needed to store the recycled waste. For Projects D and E, recycling could not be implemented due to extremely limited space. Consequently, Projects D and E were not LEED-certified. Over the life of Project B, 75 dumpsters were sent to recycling, while only 10 to 12 dumpsters were sent to a landfill. For Project C, a similar placement was used to encourage recycling. For Project A, due to the lack of emphasis on recycling, even without limitations on site storage, the recycling rates of concrete and masonry were only between 5% Vol. 16, No. 5 / July 2012

and 10%. However, because the owner of the building was not trying to achieve any sort of certification, there was no additional use of resources to monitor the amount of recycled content. Even for those projects in which waste recycling was required, the stakeholders felt that they were spending too much money simply to obtain LEED credits. The most frequently recycled materials in this study were wood, drywall and cardboard. Ironically, these were the waste materials that were generated by mismatches between the designs and manufactured material sizes. In addition, the total quantity of waste generated at the small sites did not justify the use of several recycling dumpsters because most of the dumpsters were not full by the time of collection. Although this study found that there were slightly fewer change orders (by percentage) for the large and LEED-certified projects, it is difficult to conclude that LEED and size affected the total number of change orders. Instead, the smaller number of changes may have been due to the DB method of the projects, in which the designers and contractors communicated much earlier in the design phase. As a result, design-construction conflicts were minimized.

4. Summary of Findings 1) Examine whether sustainability, particularly LEED, could affect the implementation of lean concepts in small construction projects This study suggests that the implementation of sustainability concepts can affect the implementation of lean concepts for small-sized projects, especially with knowledgeable project teams. As a project becomes larger, the impact of the use of sustainable materials may decrease, and recycling/reusing may become more justifiable. It was found that it is also more difficult to integrate lean concepts with sustainability concepts in small construction projects. Furthermore, this study also shows that the implementation of lean concepts in small construction projects may not be cost effective or relevant if the project managers simultaneously control several projects. In small construction projects, managers are less able to efficiently control the schedule of material deliveries and do not have sufficient materials to recycle. However, project managers reported that this limitation could be overcome by simultaneously managing several small construction projects and treating all of the projects as one. The increases in the number of activities and material varieties had a stronger influence on the small projects than the larger projects, although the locations and storage space availability seemed to be important as well. This study also provides some evidence that the application of lean concepts is less justifiable for projects in rural and some urban areas where congestion is not a problem. However, this relationship tends to be weaker and was found to be mainly driven by the amount of space available for work, storage and equipment. 2) Examine whether lean concepts are easier to implement in non-LEED projects Materials tended to stay on site longer for the medium-size and

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Collin Koranda, Wai Kiong Chong, Changwan Kim, Jui-Sheng Chou, and Changmin Kim

LEED projects, and the average lead time for larger items tended to be longer for the small-size and LEED projects. In short, it is more difficult to implement lean concepts for LEED projects because the time for which the larger items stay on site and the average lead time increase. In addition, this study also found that it is more difficult to integrate lean concepts with sustainability concepts in small-size projects. 3) Examine how lean concepts can be more effectively introduced into both LEED and non-LEED projects, especially small-size projects in regions where practices of sustainability and lean concepts have yet to become mainstream This study shows that the following variables influence the implementation of lean concepts in LEED or small-size projects: (1) average lead times of the larger items, (2) storage space required for large materials, (3) mixing of sustainable and nonsustainable materials, (4) the use of recycled materials and recycling on site, (5) failure to design for sustainability and lean concepts and to integrate design with construction processes, (6) quantities of materials delivered and installed on the same day, (7) site congestion involving storage space, equipment, activities, and material varieties, (8) the alignment of values for both sustainability and lean concepts, (9) perceived lean level of work productivity as part of the “green” requirements of green buildings, (10) incorporation of personal choices and marketdriven demands in green requirements, (11) sustainable materials that may affect labor productivity and site delivery methods, (12) sequencing of work operations to be considered at the design stage, (13) designs that match industry supplies, and (14) appropriate contractual arrangements. This research also concludes that sustainability and lean concepts differently define waste and value. While most large projects and those that have long-term ownership can easily justify additional costs, the small projects with shorter ownership lives cannot. Hence, these projects first need economic justification, then simpler approaches, and finally, a clearer direction in which to implement both sustainability and lean concepts. The benefits of sustainability and lean concepts cannot be achieved if only a small number of projects use both concepts. Value has different meanings to the owners, designers and contractors. The reduction of idle labor hours is more valuable to contractors, while designers do not consider labor. Hence, lean work scheduling so that the labor force remains productive may be more meaningful to a contractor than is lean material consumption. A lean workforce schedule, on the other hand, has no value to the designers. Sustainability also has yet to identify labor inefficiency as a component of waste. The interviewees agreed that sustainability and lean concepts can both help to reduce waste and can be employed simultaneously. However, as shown in Table 1, there are also other variables that may dictate whether these concepts actually reduce waste and increase the value of a project. The setting and location of a project also affect its focus. Costly land in an urban area makes JIT delivery justifiable. The project proximity to required resources also characterizes a

Fig. 1. Determining Use of Lean Concepts

project’s need for lean concepts and the impact of implementing sustainability concepts. To utilize lean concepts such as JIT delivery, an accessible location and reliable supplier are required. In addition, shipping smaller quantities over longer distances results in a less sustainable project. Fig. 1 highlights the relationship between the need for lean concepts and storage constraints. Case studies on the need for lean concepts in a construction project showed a positive relationship with relation to storage constraints: as space constraints increase, there is an increased need for resources to be dedicated to lean construction management. The size of a project may also likely have an effect on the need for lean concepts. The projects in this study that most frequently utilized lean concepts were the three large-size projects; however, the largest project did not have a significant focus on lean concepts. For the large Projects D and E, more emphasis was placed on lean concepts than was in the small Project F. This reflects the fact that the size of a building is not as significant as is the amount of free space (in terms of percentage) on the site. In Project C, one of the small projects, the managers endeavored to partially incorporate JIT methods. For Projects A, B, and C, there were low storage constraints, and thereby, the added cost for the management of lean construction was less justifiable. These case studies also clearly define a positive and linear relationship between the need to focus on recycling and JIT delivery. The decision matrix shown in Fig. 2 compares JIT delivery with a focus on recycling for each project. The points used were determined based upon the constraints faced by each project. For both JIT delivery and focus on recycling, the points ranged from 0 to 5, with 0 being no focus on either concept and 5 being a high focus. The need for JIT delivery depends on the allowable time and space available for material storage on site. The results seem to suggest that an increase in an emphasis on recycling may potentially increase the need for JIT delivery. The designs for Projects D and E were considered more challenging than those of the other projects in the case studies. As a result, perhaps there was more waste generated during construction. These two projects also did not focus on recycling but instead concentrated their efforts on lean concept implementation. For Projects D and E, with a higher percentage of waste generated during construction and without a focus on recycling,

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KSCE Journal of Civil Engineering

An Investigation of the Applicability of Sustainability and Lean Concepts to Small Construction Projects

Fig. 2. Focus of Recycling vs JIT Delivery

managers struggled to incorporate sustainability concepts with their lean processes. Table 3 compares the projects based on constructability, storage constraints, waste management focus, and JIT delivery. The table also provides a comparison of small and large projects and LEEDTM- and non-LEEDTM-certified projects. The interviewees helped to develop a generic model and process maps (Fig. 3) that further enhanced the results of this research. The interviewed designers reported that a meeting between designers and owners is needed in which the owner can convey the project goals to the designer. The designer then needs to examine the constructability of the project to determine what changes should be made so that a poor design does not lead to excess waste. It is very helpful to consult a contractor during this process to obtain in-depth advice on the needed design changes. To make this process as successful as possible, it is best if the owner and designer select a contractor to work with during the design stage (thus using the DB approach). The contractor can help identify specific design flaws that may create complications during construction. The successful implementation of sustainability and lean concepts depends heavily on the owner’s ability to finance such endeavors. Feedback also highlighted that the price of a project increases when implementing sustainability and lean concepts. For example, the incorporation of certain LEED credits could result in an additional 5-10% of the project cost. Sustainable

Fig. 3. Generic Design and Construction Process Map to Smooth the Implementation of Lean Techniques and Sustainability (Adopted from BNIM Architects, Kansas City, Missouri)

materials can have a major impact on project costs and schedules. For example, in one of the projects, the lead time for glass panels was one year. Certain sustainable materials come from distant locations because many such materials are not available in the local market. Additionally, some energy-efficient systems had to be specially manufactured and configured.

5. Framework to Integrate and Implement Lean and Sustainable Concepts The final objective of this study is to investigate the coimplementation of sustainability and lean concepts in a construction project. The integration of these two concepts when project team members have a limited knowledge of sustainability and lean concepts can be a challenge. To ease this challenge, this objective attempts to simplify the process by integrating the findings of this study with existing techniques and literature on sustainability and lean concept implementation. The process integrates the BNIM Architects’ design and construction process map for sustainable projects (Fig. 3), lean concepts, and the findings from this study, as shown in Fig. 4. The first column identifies the five bearings of sustainable construction. Only the factors of the five sustainable construction bearings that have

Table 3. Project Comparisons Variable LEED Certified Size Constructability Storage Constraints Waste Management Focus Just-in-time Delivery Variable Constructability Storage Constraints Waste Management Focus Just-in-time Delivery Vol. 16, No. 5 / July 2012

Project A

Project B

Project C

Project D

Project E

Project F

No Small Easy low Low None Small project Moderate Low High Low

Yes Small Moderate Low Very High None Large project Difficult High Low High

Yes Small Moderate Low Very High None LEED Moderate Low High Low

No Large Difficult High Low High Non-LEED Difficult High Low High

No Large Difficult High Low High

Yes Large Moderate Medium Medium Medium

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Collin Koranda, Wai Kiong Chong, Changwan Kim, Jui-Sheng Chou, and Changmin Kim

Fig. 4. Framework for Implementing Lean Techniques and Sustainability in a Construction Project

value, generate waste, are part of a process, affect project schedules and/or costs, involve on-site manpower, and can be documented can be integrated with lean construction. These factors include: 1) Sustainable Sites, Credit 1 (Sustainable Sites), Credit 5 (Site Development), and Credit 7 (Heat Island Effect): Decisions on credits 1 and 5 affect the amount of on-site space that will be available for storage and construction, thus affecting site congestion and productivity. Decisions on credit 7 affect the types of construction materials, techniques, and systems that will be used on site and thus affect schedules and costs. Decisions on credit 7 also affect space availability and thus affect site congestion and productivity. 2) Water Efficiency, Credit 2 (Innovative Wastewater Technology): Decisions on innovative wastewater technology may actually double the amount of piping needed, and additional water storage may affect site congestion and productivity. Because most contractors in the United States are very familiar with the use of efficient water systems such as faucets and toilets, decisions to use such systems have very little impact on site productivity or congestion. 3) Energy and Atmosphere, Credit 1 (Optimize Energy Performance) and Credit 2 (On-site Renewable Energy): The optimization of energy performance may result in changes to the façade system, the orientation of the building, mechanical

systems, etc., and significantly impacts the contractors due to novelty, space consumption, and less reliable suppliers. On-site renewable energy can affect productivity if it produces a significant amount of energy on site (e.g., solar panels installed over entire rooftops). 4) Materials and Resources, all credits: These credits are selfexplanatory. 5) Indoor Environmental Quality, Credit 3 (Construction Indoor Air Quality), Credit 4 (Low Emission Materials), Credit 6 (Controllability of Systems), and Credit 8 (Day Lighting and Views): Credit 3, which requires additional work for venting air quality, may affect the schedule during construction, and Credits 4, 6 and 8 affect the types of materials used during construction. Thus, both have an impact on productivity and the waste generated during construction. The last column highlights the two key issues of integrating lean concepts with sustainable concepts. The first (the top portion of the column) includes the issues on which the stakeholders should concentrate. The focuses change throughout the development phase. Implementing sustainability may mean achieving environmental goals; unfortunately, it results in higher initial costs and a longer project duration. Thus, the project team needs to clearly define the values for their project. The stakeholders will then use these values to identify waste and unnecessary processes in their project. These aspects should be

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KSCE Journal of Civil Engineering

An Investigation of the Applicability of Sustainability and Lean Concepts to Small Construction Projects

identified in the early stages and then be eliminated during the planning, scheduling, and construction stages. From planning to the end of construction, the managers have to ensure that materials are delivered and managed effectively. Finally, throughout the project, managers have to ensure that the construction processes are well known and understood. The second issue relates to the performance indicators and is noted in the bottom portion of the column in Fig. 4. The performance indicators are the essential conditions for the designers and contractors to be able to integrate lean and sustainable concepts. By checking these indicators, stakeholders make possible a better understanding of where they are in the lean and sustainable concepts integration progress.

6. Conclusions Although sustainability and lean concepts can both lead to a reduction in waste generated during construction, this study found that there are significant differences between these concepts. For example, LEED concentrates on eliminating material waste and emissions and focuses mainly on minimizing environmental impact, while lean concepts focus on minimizing waste from both materials and operations and targets the value stream of projects. The requirements for sustainability and lean concepts on a project are different, depending on the project size, locations, settings, environment, etc. This research also concludes the importance of the project size and the knowledge level of the personnel. The authors suggest that a more detailed study needs to be performed in order to quantify the relationships between sustainability and lean concepts in construction.

References Beheiry, S. M. A., Chong, W. K., and Haas, C. T. (2006). “Examining business impact of owner commitment to sustainability.” Journal of Construction Engineering and Management, Vol. 132, No. 4, pp. 384-392. Birdi, K., Clegg, C., Patterson, M., Robinson, A., Stride, C.B., Wall, T.B., and Wood. S.J. (2008). “The impact of human resource and operational management practices on company productivity: A longitudinal study.” Personal Psychology, Vol. 61, No. 3, pp. 467501. Eriksson, P. E. (2010). “Improving construction supply chain collaboration and performance: a lean construction pilot project.” Supply Chain Management: An International Journal, Vol. 15, No. 5, pp. 394-403.

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Hall, M. and Purchase, D. (2006). “Building or bodging? Attitudes to sustainability in UK public sector housing construction development.” Sustainable Development, Vol. 14, No. 3, pp. 205-218. Horman, M. J., Riley, D. R., Pulaski, M. H., and Leyenberger, C. (2004). “Lean and green: Integrating sustainability and lean construction.” Proc., CIB World Building Congress 2004, CIB, Toronto, Canada. Howell, G. A. (1999). “What is lean construction?” Proc., 7th Conference of the International Group for Lean Construction, Berkeley, CA, USA Huang, R.Y., and Hsu, W. T. (2010). “Framework development for state-level appraisal indicators of sustainable construction.” Civil Engineering and Environmental Systems, Vol. 28, No. 2, pp. 143164. Hwang, B. G., Liao, P. C., and Leonard, M. P. (2011). “Performance and practice use comparisons: Public vs private owner projects.” KSCE Journal of Civil Engineering, Vol. 15, No. 6, pp. 957-963. Imbeah, W., and Guikema, S. (2009). “Managing construction projects using the advanced programmatic risk analysis and management model.” Journal of Construction Engineering and Management, Vol. 138, No. 8, pp. 772-781. Kibert, C. J. (1994). “Establishing principles and a model for sustainable construction.” Proc., First International Conference on Sustainable Construction, CIB, Tampa. FL. Lapinski, A. R., Horman, M. J., and Riley, D. R. (2006). “Lean processes for sustainable project delivery.” Journal of Construction Engineering and Management, Vol. 132, No. 10, pp. 1083-1091. Lonngren, H., Rosenkranz, C., and Kolbe, H. (2010). “Aggregated construction supply chains: Success factors in implementation of strategic partnerships.” Supply Chain Management: An International Journal, Vol. 15, No. 5, pp. 404-411. Low, S.P. and Choong, J. C. (2001). “Just-in-time management of precast concrete components.” Journal of Construction Engineering Management, Vol. 127, No. 6, pp. 494-501. Mao, X., and Zhang, X. (2008). “Construction process reengineering by integrating lean principles and computer simulation techniques.” Journal of Construction Engineering and Management, Vol. 134, No. 5, pp. 371-381. Pulaski, M. H., Horman, M. J., and Riley, D. R. (2006). “Constructability practices to manage sustainable building knowledge.” Journal of Architectural Engineering, Vol. 12, No. 2, pp. 83-92. U.S. Green Building Council. (2011). USGBC: Intro - What LEED is. Available at http://www.usgbc.org/DisplayPage.aspx?CMSPageID =1988 (last accessed May 04.2011). Wang, P., Mohamed, Y., Abourizk, S. M., and Rawa, A. R. T. (2009). “Flow production of pipe spool fabrication: Simulation to support implementation of lean technique.” Journal of Construction Engineering and Management, Vol. 135, No. 10, pp. 1027-1038. World Commission on Environment and Development (1987). Our common future, Oxford University Press, Oxford.

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RELATION BETWEEN THE SUSTAINABLE MATURITY OF CONSTRUCTION COMPANIES AND THE PHILOSOPHY OF LEAN CONSTRUCTION Ivna B. Campos1; Deborah M. de Oliveira 2; Sarah B. M. Carneiro3; Ana Beatriz Luna de Carvalho4 and José P. Barros Neto5 ABSTRACT In the current economic context, the influence of globalization on business requires the entrepreneur to adopt competitive posture in market. Thus, in the civil construction industry, it is known that companies seek new processes, products and tools to maximize efficiency. The Lean philosophy and the environmental management are considered strategic practices and seek to reduce waste due to the organizational efficiency. The application of these philosophies requires investments by companies, making substantial to measure it continuously. This study aims to analyze the relationship between Lean Construction (LC) concepts and sustainable construction, by the use of assessment tools that show maturity indicators of the companies involving both approaches. About the methodological procedures, this is a qualitative research with an exploratory approach. The multiple case study was used as research strategy in two construction companies located in Fortaleza, Brazil. As results, was observed that application of Lean and Green have similarities and complementarities. Therefore, the main contribution of this research is the fact that companies could achieve their process more efficient and with more quality when they implement Lean and sustainable principles simultaneously. KEYWORDS Sustainability, Lean Construction, Construction Industry, Indicators. INTRODUCTION The relationship between the Lean Construction (LC) principles and the sustainability are the study objects in this paper. Horvath (2004) consider that the civil construction industry is one of the most polluting, because of the waste generated during the building life cycle. Several business organizations seek to avoid waste and pollution, 1

2

3

4

5

Engineer, M.Sc. Student, Department of Structure and Construction Engineering (www.deecc.ufc.br), Federal University of Ceará, Campus Universitário do Pici, Bloco 710, CEP 60455-760, Fortaleza, Ceará, Brazil, Phone +55 85 3366-9607, [email protected] Architect, M.Sc. Student, Department of Structure and Construction Engineering, Federal University of Ceará, Brazil, [email protected] Architect, M.Sc. Student, Department of Structure and Construction Engineering, Federal University of Ceará, Brazil, [email protected] Engineer, M.Sc. Student, Department of Structure and Construction Engineering, Federal University of Ceará, Brazil, [email protected] Professor Ph.D Professor from the Civil Construction and Structure Engineering Department, Federal University of Ceará, Brazil. [email protected]

considered forms of inefficiency (Rao and Holt 2005). It can be stated that the implementation of LC can ensure competitive advantage for construction firms (Lewis 2000), as well as the search for sustainability. The LC emerged from the work of Lauri Koskela (1992), with the adaptation of Lean Production principles to civil construction. These principles seek to optimize the flows of production, considering the activities of conversion, inspection, moving and waiting, reducing the waste of time and resources (Koskela 2000). The concept of value with focus on customer needs and the continuous search for quality are prioritized. Kibert (2007) determines the principles required in green buildings: reduce, reuse and use recyclable resources, protect nature, eliminate toxic elements, apply life-cycle costing and focus on quality. Asiedu et al. (2009) consider the sustainability in construction as a process that reaches harmony between natural and built environments in four attributes: social, economic, biophysical and technical. The theory of LC and sustainability practices in construction shows that they are able to reduce waste for organizational efficiency, been adopted as strategic practices (Yang et al 2010). The adoption of such practices depends on the manager of each organization. There are companies that adopt the exclusively the LC, while others focus on sustainable practices. There are also companies that do not intend to adopt any of the two practices, while others seek to adopt both the LC and the principles of sustainability in construction projects, generating positive effects on AEC industry (Yang et al. 2010; Mao and Zhang 2008; Gutiérrez 2007; Kohler and Lützkendorf 2002). Some authors believe that the LC has a positive impact on the sustainability of buildings (Horman et al. 2004; Huovila and Koskela, 1998; Lapinski et al. 2006; Luo et al. 2005; Riley et al. 2005). On the other hand, other authors state that not always lean practices generate positive impacts, because the adding value by the customer's needs does not always result in reduction of environmental impacts (Cusumano, 1994; Rothenberg et al. 2001). Bae and Kim (2007) claim that LC interferes in sustainability considering the following prospects: economic, due to the economy of resources, social, by allowing health, safety, communication and loyalty between the employees and environmental, by eliminating waste and resource conservation. To understand the level of LC and sustainability application in companies and their possible interactions, it is important to use models that are able to quantify concretely the degree of Lean and sustainability implementation. However, some authors highlight the difficulty of measuring the implementation of these philosophies (Oliveira et al 2010; Bellen 2006). It is important to state that during the development of this work, weren't found models that measure both the LC and the level of sustainability. This paper analyses the relationship between Lean and Green by the application of two tools and consider the assumption that the methodology proposed by Hofacker et al. (2008) is able to assess the degree of LC implementation in construction companies and that the measurement model of corporate sustainability proposed by Farias Filho et al. (2009) is sufficient to quantify the sustainable maturity of the organization researched. Other factors may influence the evaluation of performance on companies, but they will not be considered.

Proceedings for the 20th Annual Conference of the International Group for Lean Construction

The Relation Between the Sustainable Maturity of Construction Companies and the Philosophy of Lean Construction

Thus, this study aims to analyze the relationship between the concepts of LC and sustainability through the application of assessment tools that show indicators of maturity on companies regarding the two approaches. It is intended to test the following hypothesis: the application of LC on itself contributes to sustainable maturity of the company, as well as application of sustainable procedures would make the building production more Lean. LEAN CONSTRUCTION EVALUATION TOOL The LC implementation by itself doesn't guarantee the quality of building. It's necessary to evaluate its progress. Considering the difficulty of measuring and evaluating and the advantages of LC concepts in construction companies, many methodologies have been created, such as the Rapid Plant Assessment, developed by Goodson (2002) the model for assessing the level of lean manufacturing firms, created by Soriano-Meier and Forrester (2001), and The Lean Construction-Quality Rating Model (LCR), proposed by Hofackeret al. (2008). The last one is the tool adopted in this work. The LCR proposes a model to evaluate the quality and application degree of LC in building companies. The development of this tool involved a brainstorm phase, which were defined its categories and assessment points. The evaluation of LCR was based in a questionnaire with thirty questions to be answered by the researchers. This model was developed considering the five principles of Lean Thinking established by Womack and Jones and the eleven principles of LC from Koskela's theory. The questionnaire has six categories: (1) Client Focus, (2) Waste, (3) Quality, (4) Material Flow, (5) Organization, planning and information flow, (6) Continuous improvement. The evaluation of buildings indicates scores from zero to six for each issue. The final score provides the obtaining of an average which indicates the company classification according to the application degree of the lean construction. The buildings can reach twelve levels on a classification scale which goes from level D (the lowest one, the least Lean) to level AAA (the most elevated, the most Lean), according to Figure 1. SUSTAINABILITY EVALUATION TOOL Considering the sustainable development that involves the balance between the socially desirable, economically viable and environmentally friendly, it is perceived that the implementation of its principles provides advantages to the corporate environment. There are some tools for measuring sustainability in companies, such as Global Reporting Initiative, the IChemE Sustainable Development Progress Metrics; DowJones Sustainability Index World, Guide to the Multinational Organization for Economic Cooperation and Development (OECD) and Ethos Social Responsibility business (Delai and Takahashi 2008). The application of these tools requires investments by the companies, making necessary its continuous mensuration. Given this, Farias Filho et al. (2009) developed a self-assessment tool to perform the sustainable measurement, focusing on companies of the construction industry that adopted sustainable strategies, but have few resources to invest in other instruments.

Environment, Sustainability, and “Green”

The tool is a matrix with three dimensions, 3x4x4 order. Each axis has one of three dimensions of evaluation, described below. In the contents, are 48 elements, with sustainable features that should be achieved by companies, coming from relationship of these dimensions, namely: • The sustainability tripod: consider the economic, environmental and social dimensions. • Strategic themes of Balanced Scorecard: addresses the most important performance indicators of organizations, considering the “financial” aspects, to observe the generation of impacts and economic values; “customers”, which assesses the sustainable practices considering the public of the organization; “internal processes”, whose goal is to analyze the companies' actions considering the optimization of processes and “learning and knowledge”, which evaluates the training and learning of stakeholders. • Corporate Sustainable Index (ISE): characterize the organization through the “perspective of policy and planning”, analyzing if corporate policies are able to consider the three dimensions of sustainability tripod, “perspective of management”, which evaluates the interference of strategic planning in sustainability, the “perspective of performance”, involving performance and the “perspective of legal compliance”, which intends to verify the agreement between the company and the law. The general manager of the company should evaluate all the elements from matrix, assigning a value in each sentence that varies between zero to four. Higher values indicate more sustainability. It is important to state that each element interferes differently in organizational sustainability, requiring the determination of relative weights which must be multiplied to results of self-assessment. Thus, a final score is generated, allowing to rank the company in a level of sustainable maturity as defined in Figure 2: RESEARCH METHOD This present work is a qualitative research which presents as strategy research the multiple case study with an exploratory approach. According to Yin (2005), qualitative studies are used when researchers use sentences like "how" and "because", when they have weak control of the events and when the research focuses in a contemporary phenomenon inserted in a real context. About the research goals, Gil (2009) states that exploratory approach have the main intention to make the problem more explicit. Therefore, procedures are used, as literature survey, interviews with people who had practical experience with the problem, and the analysis of examples that will support the scope of the problem. Therefore, it makes possible the consideration of several aspects related to the fact studied. In accordance to the goals of the research, the following steps have been taken to the work development: (1) Literature review involving the principles of LC based on the work carried out by Koskela (1992), and the study of insertion the environmental management in companies. (2) Selection of evaluation methodologies used in the research: Rapid Lean Construction-Quality Rating Model (LCR) from Hofacker et al. (2008), to evaluate how much the LC philosophy has been applied in construction;

Proceedings for the 20th Annual Conference of the International Group for Lean Construction

The Relation Between the Sustainable Maturity of Construction Companies and the Philosophy of Lean Construction

and the tool for evaluation of the sustainability maturity level in civil construction corporations, developed by Farias Filho (2009). (3) Application of the methodologies in two case studies (4) Analysis and discussion about the relationship between the LC concepts and the sustainable maturity of companies.

Figure 1: Comparison between the classification of the works of companies (Figure 6 in Oliveira et al. 2010).

Figure 2: Levels of maturity sustainable of companies (Figure 3 in Farias Filho et al. 2009).

The assessment tool proposed by Farias Filho et al. (2009) does not propose to examine the ways of sustainability implementation in the company, but the sustainable strategy already implemented in a place. Therefore, the use of this tool is justified because it allows companies of all sizes to evaluate in an easy and complete manner their sustainability performance, providing improvements for them. Hofacker et al (2008) developed a model for assessing the quality and degree of LC implementation in building companies, offering a categorized assessment with easy viewing and interpretation of results. Oliveira et al (2010) applied the LCR in four construction sites: two in Curitiba (Brazil) - where did not apply the philosophy, one in Porto Alegre (Brazil) and one in Sindelfingen (Germany)- both implemented the LC philosophy on site. The use of LCR is justified due to its characteristics, namely: application in a short time, in less than one hour; items organized by categories; simple and complete interface. It is necessary to researchers only the direct observation of the building and a conduction of an interview with the engineer responsible for building. Besides the advantages mentioned above, these instruments were selected because of their specific use in civil construction sector. SAMPLE CHARACTERIZATION

This research was carried out through two case studies that took place in construction companies which had one of their works each analyzed. The Company A, which is classified as medium sized company, started its activities in 1989. It has 20 completed buildings, among them commercial and residential constructions and their clients are from A and B social classes. This company’s philosophy aims to meet their clients’ needs with efficient products at a very fair price. The considered building is in a certification process, aiming the Leed Silver level. The case study from Company A is a commercial building, which is located on a very wealthy area of Fortaleza-Brazil. It is made of four underground levels with

Environment, Sustainability, and “Green”

nineteen flooring types. This construction was at a structural stage, having its last underground level being concreted. The company B, which is also a medium sized company, initiated its activities in 1988. It also has 20 concluded buildings, among them commercial and residential constructions for the A and B social classes. Its work philosophy is based on the good quality of services provided. This company aims to please clients, associates, and employees through innovation, continuous improvement, a more closely relationship regarding honesty and mutual trust. This company applies the LC philosophy concepts to its entire works. The building of the company B is also a commercial construction located in the city of Fortaleza, Brazil. It is made of two underground levels with eighteen floors types. The construction was at a structural stage, with ten flooring types already concreted and with its masonry under execution. RESULTS RESULTS OF COMPANIES FOR THE IMPLEMENTATION OF LEAN CONSTRUCTION The companies A and B presented distinct scores during the application of LCR. The six characteristics presented by both companies are analyzed, briefly explained and displayed in Table 1. In the analysis of category “Client Focus”, the company B had an advantage by using a program of construction site cleaning (5S). The company A should implement a 5S program for LEED certification requirement, but had not been contemplated until the end of the study. Other requisites under the consideration of clients’ wishes in terms of sales, marketing, strategic focus, and flexibility did not make the two companies score, for considering as client the developer rather than final user. Thus, both companies showed their worst performance in the client focus category. As for the waste, the company B presented excellent scores, making it far ahead of company A. It is wise to say that both companies have Waste Management Plan, which is required by Brazilian law by resolution 307/2002 of CONAMA. However, the company B goes beyond in this matter for the application of LC principles, and this reflects specially on its effective and organized use of construction site layout. As for the “Quality”, the company A overcame the company B. In this category the company A presented the highest score for its high degree of mechanization through the use of crane and rack lift, and the elaboration of reports that would show the cause of possible mistakes. This last action was not present in company B. The two analyzed companies have quality management systems, the company A was certificated by PBQP-H and ISO9000, whereas the company B has ISO9000 certification and has also developed its own quality system, called PS37. At last, the visual management as guarantee of quality exists in the two companies, but it happens by deficient way. By considering the “Material Flow and Pull” category, both companies presented an average performance, being the company B a bit better than company A. This last one reached scores due to the use of ready-mix concrete, a system to organize the material weekly orders, support and standardization of transports, use of cranes and pallets. About company B, besides meeting the same requisites as company A, it

Proceedings for the 20th Annual Conference of the International Group for Lean Construction

The Relation Between the Sustainable Maturity of Construction Companies and the Philosophy of Lean Construction

implemented the Just-in-Time concepts, with daily measurements of the amount of storage and use of Kanban cards in a preliminary way. Table 1: Characteristics evaluated by the LCR (The authors) COMPANIES Client Focus

A

B

Detecting what is value for the client, in terms of sales, marketing, strategy 8,3% 25,0% focus, project flexibility and cleanliness of the construction site.

The process to reduce the wastes and losses in theirs construction site, Waste stimulating waste management, space organization and reduction of wasted 50,0% 93,3% Consciousness time Quality

Search the quality through the certifications, good performance of services, safety on the construction site, prevention of rework, standardization of 85,4% 70,8% processes, visual management systems and mechanization

Evaluate the implementation of LC tools, such as: Kanban, Just in Time, readyMaterial flow & mix concrete, system application with replacement time of the materials, 50,0% 63,3% pull mechanization and transport standardization Organization, planning, info flow Kaizen

Knowledge of the top management about Lean Construction, motivation and self-responsibility of the employees and the Last Planner System applied with 19,4% 52,8% daily hurdle meetings. Striving for perfection and for continuous education for the employees

50,0% 66,7%

With respect to “Organization, Planning, info flow” category, company A presented a non-satisfactory performance, while company B presented an average performance. The scores achieved by company B were granted due to the application of LC principles, by using versatile employees, vertical and horizontal information systems, and payment through work packages. Company A seems to be unaware Lean tools by taking conventional actions, using employees with specific tasks and a deficient communication system. Although the two companies seek the kaizen, company B reached the best scores, for it promoted improvements in a more adequate manner with incentive to the education of its employees through training courses. Based on this evaluation, Company A reached a CC level, with 43.6% of the requisites fulfilled. Company B reached a B level with 62% of the requisites fulfilled as it can be observed in Figure 3: Even that the company A was unaware of the Lean principles, it was still able to reach average results, because the search for LEED certification involves the consideration of LC strategies, such as: waste management, search for quality, and employee training. Company B reached scores expected of a company that really applies the LC principles. However, improvements still can be made, especially in terms of meeting the clients’ needs, improved signal, rework analysis, and higher level of mechanization. RESULTS OF COMPANIES FOR THE SUSTAINABLE MATURITY By analyzing the level of sustainable maturity of the two companies, it was observed that company A had a better performance than company B, by reaching a result almost the double score. This can be observed in Figure 4:

Environment, Sustainability, and “Green”

62,0% 43,6%

AAA AA A BBB BB B CCC CC C DDD DD D

Figure 3: Levels of LEAN construction application of A and B companies (The authors).

Figure 4: Levels of sustainable maturity of A and B companies (Adapted to Farias Filho et al. 2009).

Company A reached 242.1 scores and was classified as "Voluntary", explained by the intention in certifying the construction according to the LEED Silver, encouraging managers and employees to have a proactive attitude. In order to reach the LEED certification, it is necessary to fulfill a series of criteria and requisites that demand integrated learning and taking advantage of existent sustainable opportunities. Company B presented a maturity level classified as “Reactive”, reaching 123.3 scores because that company doesn’t have a sustainable approach in their strategies. However, the implementation of LC principles and requirements of urban laws makes sustainable measures to be adopted, such as: optimization of production processes, waste management measures, work organization, and waste reduction. It is important to highlight that out of the three sustainability pillars considered by the tool, the economic pillar presented the best performance for both companies if compared to the environmental and social pillars. This reinforces theories that state that the economic sphere should be of top priority in developing nations. CONCLUSIONS Considering the goal of this research, it can be observed that both methodologies have points in common, like the reach of quality, the reduction of waste, the information flow between employees and managers and the search of continuous improvements. Some civil construction companies use the LC and sustainability as a competitive advantage. However, to achieve results, is necessary the awareness and commitment of all employees involved, even as the processes must be transparent. During the development of this research, it was found that Company B reached reactive level in sustainable tool, even without the focus on environmental issues. This company presented good results in sustainability because it seeks to reduce waste, to optimize production processes and to raise the level of interaction among employees. About Company A, it reached a median level on LCR tool. This is a reasonable score, considering that the top management and employees ignored the importance of applying the LC principles. This company presented a good rating in Lean evaluation because implemented sustainability guidelines in pursuit of LEED certification.

Proceedings for the 20th Annual Conference of the International Group for Lean Construction

The Relation Between the Sustainable Maturity of Construction Companies and the Philosophy of Lean Construction

Given the above, this research hypothesis was confirmed: the LC application contributes to sustainable maturity of the company, as well as the implementation of sustainable procedures can make the building more lean. Therefore, through the evidence provided by this study, it was observed that both concepts have similarities and complementarities. The application of sustainability in a building does not guarantee the full range of Lean benefits, but reinforces a good performance on the issues that the two philosophies have in common. The same goes for Lean Construction in relation to sustainability. However, the companies may present more efficient process and higher quality if the LC and sustainable principles were applied at the same time. This paper presents the following limitations: • The research conducted two case studies in construction companies, analyzing one work of each. A larger amount of companies evaluated could presents more detailed results about the relation between Lean and Green. • One of the buildings uses Lean principles, while the other seeks environmental certification. The inclusion of a company that did not use any of these strategies on research could be a reference, contributing to the comparison of case studies. • The measurement model proposed by Farias Filho et al. (2009) consists on a self-assessment tool developed based on sustainability indicators. It was applied directly to the company directors of companies. For this reason, there is an upward trend of the ranking, differently if the evaluation was performed with other people. Thus, it is suggested future works to overcome these limitations. Besides these, it is suggested the proposition of a theoretical study joining the two assessment tools, resulting in a unique methodology of analysis. The case studies considered only commercial buildings. It would be interesting contemplate residential buildings in a future research, where there more focus on customer needs. ACKNOWLEDGMENTS We thank CAPES and FUNCAP for the financial support to this research, GERCON for making their data available, and to the managers and employees of both companies evaluated, for their collaboration enabled this research to happen. REFERENCES Asiedu, W.G., Scheublin, F.J.M. and E.L.C. Van Egmond De Wilde De Ligny, (2009). “The Elements in Sustainable Const. Industry: Building Criteria and Indicators for Performance Assessment”. Proc. 3rd CIB Int’l Conf. on Smart and Sustainable Built Env., Delft, Netherlands. Bae, Jin-Woo and Kim, Yong-Woo (2007). “Sustainable Value on Const. Project and Aplication of Lean Const. Methods”. Proceedings IGLC-15, Michigan, USA. Bellen, H. M. van. (2006) “Indicadores de sustentabilidade: uma análise comparativa”. Rio de Janeiro: FGV Editora. Cusumano, M.A. (1994). “The Limits of ‘Lean’,” Sloan Mgmt. Rev., v35 (4), 27-32. Delai, I. and Takahashi, S. (2007) “Uma proposta de modelo de referência para mensuração da sustentabilidade corporativa”.Proceedings Encontro Nacional sobre gestão empresarial e meio ambiente, Curitiba.

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Ain Shams Engineering Journal 9 (2018) 1627–1634

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Architectural Engineering

Examining the interaction between lean and sustainability principles in the management process of AEC industry Laila M. Khodeir ⇑, Reem Othman Department of Architecture, Faculty of Engineering, Ain Shams University, Cairo, Egypt

a r t i c l e

i n f o

Article history: Received 28 May 2016 Revised 27 November 2016 Accepted 18 December 2016 Available online 29 December 2016 Keywords: Sustainability Lean Architecture, Engineering and Construction

a b s t r a c t Architecture, Engineering and Construction (AEC) industry is classified as a huge consumer of natural resources. It consumes 50% of natural material resources, 40% of energy and is responsible for 50% of total waste. Subsequently, different sustainability indices and environmental certifications have been introduced to AEC. As a result, most construction firms turn to green building designs and acquire different environmental certifications. Recently, the concept of lean management has been introduced to AEC after succeeding in manufacturing. This paper aims at examining the interaction between lean and sustainability principles on the management process of design and construction projects. Towards achieving this aim, two approaches were employed, namely literature review, and a correlation matrix to verify the area of interaction between both lean construction and sustainability principles. Findings took the form of guidelines for AEC companies to help in applying the integrated lean and sustainability principles on managing design and construction processes. Ó 2016 Ain Shams University. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

1. Introduction Sustainability has caught a great attention in all industries and researches worldwide, after the publication of the report of World Commission of Environment and Development (WCED), ‘‘Our Common Future” in 1987, which was the first to bring sustainable development to the international discussion. It highlighted the relation between society, resources and environment through a long-term environmental perspective to achieve sustainable development [1–3]. In addition, the recognition of the problem of resources and the effect of all industries on the surrounding environment was emphasized in 1992, Agenda 21 of the United Nations Conference on Environment and Development or ‘‘Earth Summit” stated that: ‘‘sustainability should have some standard indicators to control and monitor the sustainability development in all levels”. Since that time, many efforts have been exerted in order to track and test sustainability and provide guidelines to achieve sustainability development in different disciplines [2]. ⇑ Corresponding author. E-mail addresses: [email protected], [email protected]. eg (L.M. Khodeir). Peer review under responsibility of Ain Shams University.

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Sustainability through reduction of resources wastes and increase processes efficiency is the main goal of all sectors. For instance, agricultural sector consumes about 92% of the water resources in Iran [4], which driven researchers to try to search for more effective way of irrigation. Architecture, Engineering and Construction (AEC) industry was among the industries that followed the principles of sustainability. AEC industry is consuming about 50% of the material resources coming from nature, 40% of energy consumed and responsible for 50% of total waste generated. So, it is one of the prime industries that should care about sustainability [5]. Thus, different rating systems were developed to measure sustainability in quantified methods and provide guidelines to achieve sustainability in the building operation or through onsite processes. Among those methods are the Building Research Establishment Environmental Assessment Methodology (BREEAM) in Europe, the Building Environmental Performance Assessment Criteria (BEPAC) in Canada and the Leadership in Energy and Environmental Design system (LEED), which was introduced by the green building council in USA [2]. Nevertheless, those rating systems focused mainly on achieving sustainability in Construction, in operation of a process or on site processes, paying less attention to applying sustainability principles on the design or in office processes that have tangible wastes (see Tables 1–3). At the time AEC industry raised attention to embracing sustainability principles into its processes, the emerging concept of ‘‘Lean” has proved to be feasible when applied on AEC as well. The Lean concept has actually originated from Toyota production system

http://dx.doi.org/10.1016/j.asej.2016.12.005 2090-4479/Ó 2016 Ain Shams University. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

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Table 1 The impact of applying ‘‘Kaizen” tool to sustainability tri bottom line. Sustainability pillars

Case (1) Gypsum board hanging

Environmental sustainability Economic sustainability

64% Material waste reduction

Social Sustainability Conclusion

Case (3) Base framing

1st Coat:83% savings in man-hours 2nd Coat:71% savings in man-hours 31% savings in total man-hour 26% savings in overall cycle time.

55% cycle time reduction

Eliminate hazards Increase worker safety 16% improvement in value-added activity

15% improvement in value-added activity

Table 2 The Researchers’ opinions on Lean and sustainability interaction. No.

Case (2) Interior painting

The relation between lean and sustainability

Lean achieves sustainability agenda 1 Lean is the way to achieve a new holistic view of sustainability as an integration of process efficiency (i.e. cost, time and quality) and sustainability concept (i.e. environmental quality, social equity, health economy) [19] 2 Lean construction achieves sustainability in its tri pillars: economic due to the reducing of resources and cost; social by allowing health, safety, working environment and loyalty between the stakeholders; and environmental by eliminating waste, reducing pollution and resource preservation [17,18] 3 Lean construction and sustainability share the same agenda of waste reduction and increase efficiency, but with different approaches. Lean is short term as it affords high performance process, while sustainable construction is a long term through the whole building life cycle [10] 4 ‘‘Sustainability dimension is inseparable of lean, since reducing energy consumption and preserving the environment is one of the ultimate longtime waste reductions” [20] Lean does not match sustainability main agenda especially ‘‘Environmental Pillar” 5 Lean is not green as its main objective is to maximize the customer value. It is not necessary that customer value matches the environmental issues. They believe that lean achieves sustainability by accident, not because it is its main concern [13] 6 Implementing Lean practices only has a very low effect on the environmental performance of company [11] Lean and sustainability integration 7 ‘‘The lean thinking is the first step towards a sustainable future”. They proclaimed that environmental sustainability is the next step of lean philosophy to reduce the negative effect of product on the environment and safe resources, as the Japanese auto-manufacturing industry starts with lean towards the currently hybrid engines and vehicles with recycled components [21] 8 ‘‘Sustainable practices are the normal extension of lean philosophy in the operational phase” [11] 9 ‘‘The applications of Lean and sustainability have similarities and complementarities”, so companies could achieve more efficient performance, if they concurrently implement Lean and sustainable principles [17,11]

(TPS) in automobile manufacturing in 1950s in Japan, where Lean was intended to deliver the customer value instantly and without inventory [6]. Since then, Lean has focused on both maximizing customer value and minimizing all types of wastes. Afterwards, TPS passed by various evolutions and succession in manufacturing industry before it has been introduced to AEC industry. In his report to Center for Integrated Facility Engineering (CIFE) at Stanford University in1992 [7], Koskela studied the philosophy of lean production and the deficiencies of the traditional system in AEC industry. He concluded that to apply lean concept in AEC processes, it needs to increase the efficiency of conversion activities and reduce the flow activities. Thus, he proposed eleven principles to apply lean in the construction context that implies solutions for the AEC problems [7]. It was only after the publication of Koskela report that Lean concept has started to be a common trend that captured the attention of all researches in the AEC sector. Fig. 1 shows the timeline for both sustainability and lean.

Table 3 Lean principles. Lean principle

Description

Reduce non value-adding activities

Reduce any activity that consumes any type of resource or time and adds no value to the customer The clear identification of all customers and their needs in each activity from the start point, and achieve their values Reduce the uncertainty through the wellknown of everything from the first point, and identify standards and values clearly for each participant from the start Reduce the total time in which the activity took place from processing till finishing. Reduction of cycle time consequently led to minimize the possibility of interruption of process and maximizing the customer delivery Simplify the processes which lead to the product through removing any non-added value activities, allowing easy information flow, etc. Do each activity in its last allowable time (Just-In-Time principle), which increases the ability for catching any change orders Allow all the production process activities and the information anytime for all the employees and participants. This helps in reducing errors and allows easy monitoring and improving of the process The holistic monitoring and controlling of the production process Implement a continuous improvement to the whole process and employees through allowing employees to improve themselves and the whole process and make reward system to encourage employees. Pass from the monitoring of the process to the improvement of the process Improve both flow and conversion of activities. High controlling of the flow will lead to conversion improvement Study your competitors and compare your process with the best in the world. It is about the self-evaluation of your production process to improve yourself

Increase consideration of customer requirement Reduce variability

Reduce cycle time

Simplify by minimizing the number of steps and parts

Increase output flexibility

Increase process transparency

Focus control on the complete process Build continuous improvement into the process

Balance flow improvement with conversion improvement Benchmark

Most of the researches whether in lean and sustainability trends either in manufacturing or AEC sector identify how applying lean principles and tools achieve sustainability, or study the relation between lean and sustainability while sustainability is always a passive element. On the contrary, this paper examines the role of sustainability to achieve lean main objectives. The objective is fulfilled through literature review of the recent previous studies in lean and sustainability trends in AEC industry. The paper also aims to verify the ability of sustainability to match lean in the management process of AEC industry.

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Mass production (Henry Ford)

Automobile Manufacturing

Innovation of TPS in Manufacturing

1908-1913

- Coining the Term “Lean” - Translating TPS into five main principles.

1950s

1987

“Our common Future” Bringing sustainability development to international discussion

1990

Koskela report that introduced lean to AEC industry

Launching of International Group of Lean Construction

1992

1993

“Earth Summit” sustainability should have some standard pillars and indicators

To AEC Industry

Lunching of US Green Building Council (USGBC)

Figure 1. Timeline for sustainability development and Lean Progress. Source: Authors, based on extant literature.

2. Introducing concepts of lean and sustainability in AEC industry Since sustainability and lean construction have originated as trends that were introduced to AEC industry in a separate manner, researchers studied the effect of both trends on AEC industry independently and observed their benefits. Then Researchers have shifted towards studying the relation between Lean and sustainability, and how lean principles and techniques can achieve sustainability in AEC industry. Actually, the relation between lean and sustainability is debatable among extant literature. This debate can be categorized as: (1) studies advocate the absolute relation between lean and sustainability, (2) Studies claimed a conditional relation between those two trends. (3) Studies that seeking the integration between lean and sustainability. The next part will detailed demonstrate these arguments. 2.1. Lean achieve sustainability theoretically Most of research studies have proven that lean principles match sustainability’s main objectives and achieve its main agenda regarding processes, owing to the potential of lean in eliminating wastes, improving the whole process and reducing the negative impact of construction projects. Firstly researchers studied the relation between lean and sustainability theoretically to conclude that lean achieve the main agenda of sustainability while, lean is considered a short-term concept as it affords high performance process, while sustainable construction is classified as a long term through the whole building operational cycle [8,9]. Similarly, Golzarpoor and González [11] have stated that ‘‘sustainable practices are the normal extension of lean philosophy in the operational phase”. Furthermore, Environmental Protection Agency (EPA) claimed that lean produces an operational and cultural environment highly conducive to waste minimization and pollution prevention which promotes sustainability in processes [11]. Also, [12] proclaimed ‘‘Sustainability dimension is inseparable of lean, since reducing energy consumption and preserving the environment is one of the ultimate longtime waste reductions”. By another mean, [13] proclaimed that lean concept wasn’t originated to protect the environment as sustainability, However, both concepts sharing close objective of reducing wastes for different purposes. Sustainability eliminates material wastes going to landfill to reduce its impact on environment, the negative effect of its production process on the environment and the CO2 emissions, while lean eliminates tangible and intangible wastes to increase the process efficiency and satisfy the customer. Thus, lean focuses on the production process while sustainability focuses on the product. They added that lean have some tools that help achieving the sustainability. Recently, some researches supported the vast role that lean can play to achieve sustainability, where Campos et al. [14] have stated that Lean achieves sustainability in its tri dimension, economic dimension through reducing resources and cost, social dimension

by allowing health, safety, working environment and loyalty between the stakeholders and environmental dimension by eliminating waste, reducing pollution and preservation of resources. 2.2. Case study of the role of lean in achieving sustainability A case study [15] lately studied the contribution of lean in achieving sustainability practically. They observed the impact of one of the lean tools called Kaizen1 on achieving sustainability in its triple dimensions, where three case studies of the construction of modular housing were analyzed. The researchers concluded that using this tool can affect the environmental sustainability by reducing material waste by 64% in gypsum board hanging process, and the economic dimension by reducing working hours by 31% in the interior painting process. Social dimension was accomplished by increasing worker safety and a 15% improvement in value-added activities. Similarly [16] claimed that implementing lean tools significantly achieve environmental benefits through a case study; in which reducing material wastes was translated as reduction in the raw material waste. Consequently, the reduction in the negative effect of production and transportation processes on the environment. Also decreasing the labors hour through reducing the rework, leads to decrease the transportation trip of labor and material that consequently reduces the percentage of greenhouse gas produced by transportation vehicles. They verified this claim though comparing the insulation of drywall panels in two phases of heath care project, and observed the percentage of CO2 gas emission through the production process of drywall panels, the labor hours, duration and Cost of each phase. They concluded that applying Lean tools as BIM, pull planning, IPD (Integrated Project Delivery), and all participant involvement in phase II; lead to reduction the labor hours by 20% and the Material wastes by 6% compared to phase I. In addition this reduction in material wastes reduced 7.5 tons of CO2 emission during the production, transportation, and insulation of drywall panels on site. 2.3. Lean and sustainability conditionally A third group of researchers tried to trace the relationship between lean and sustainability principles in an objective way. They put specific conditions that could support the relationship between both concepts. Among them are Kim et al. [17] who assumed that lean could be considered as a sustainability practice, only when customer values are sustainable. This turned the relationship between lean and sustainability into a conditional one, where it depends on the nature of the customers’ main values and how they understand Lean Values. Similarly, [18] claimed that 1 Kaizen is a tool that seeks continuous improvement of the whole process performance based on team work management through leadership and employee involvement to reduce wastes and any non-added value activity and increase process efficiency [15].

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lean tool, like Just in Time (JIT), support sustainability in case of large lot delivery order and committed suppliers. As JIT might cause increase in CO2 emission in case of the small lot delivery order or uncommitted suppliers. While both researches ended their research by concluding that lean tools have a clear positive impact on social, economic and environmental sustainability if the previous mentioned conditions were considered. 2.4. Lean does not achieve sustainability On the other hand, another group of researchers argued that lean concept does not support achieving sustainability. Among those researchers are Kim et al. [19], who claimed that most studies in lean construction field concentrate on lean principles and tools, as a method to reduce wastes, time and the initial cost, not as an approach to reduce environmental impact or improve the social dimension of processes. In addition, Rothenberg et al. [20] claimed that lean does not achieve sustainability as lean is not ‘‘Green”, according to their research. From the perception of this research, the main objective of lean is to maximize the customer value, which should not necessarily match environmental values. They also added that lean could only achieve sustainability by accident, not because it is its main concern. 2.5. The relation between lean and sustainability indices On the other hand, some researchers studied the relation between lean principles or tools and different sustainability indices. For instant, [8] studied the correlation of Lean tools and sustainability indicators of the sustainable construction index of a Portuguese company. Soares da Costa Company adopted their own Sustainable Construction Index (SCI) to track their sustainability performance. They concluded that applying 5S, Kaizen, Value Stream Mapping (VSM), last planner tools can mostly affect the accidents, total waste production indicators of SCI. In addition by comparing the performance and productivity of the company in general after implementing lean tools. They concluded that implementing lean tools enhances the company performance above its normal average. In addition [21] studied the correlation between the eleven lean construction principles proposed in Koskela report [7] and environmental pillar of sustainability (i.e. LEED criteria’s). They compared the total number of all the possible relations to the actual relations to proclaim that lean construction principles match LEED criteria’s by 12.68%. They argued that this low interaction occurred due to the natural of each approach, in which LEED focuses mainly on the environmental performance from the project definition to the operation and ignore the improvement of working conditions and safety, or layout configuration for waste reduction. In contradict, lean focuses on the production system and process, and cost and time reduction. Finally, they added that both Lean and LEED have obvious benefits to construction industry such as waste reduction, continuous improvement, and competitive issues; in which lean focuses on the short term processes while LEED focuses on the long term operational process. Thus, applying both approaches maximize the benefits to the construction industry. Finally, Since Campos et al. [14] stated that Lean and Sustainability applications have some similarities and complementarities, companies should implement sustainability and lean principles concurrently to achieve more efficiency in the processes. 2.6. Integration of lean and sustainability into the whole building life cycle Some studies tried to imbed sustainability into lean concept to integrate their benefits. For instant, Kosklea and Huovila [23] was

the first who proposed an integrated framework for lean and sustainability concepts. They studied how to achieve the values of all stakeholders in sustainability manner by considering the environment as one of lean customers and achieve its values. Similarly, in 2006 US EPA tried to imbed sustainability into lean to achieve the most benefit through adding the environmental values to the traditional value stream mapping through identifying the amount of the raw material totally consumed in the process and the percentage of the material that appeared finally in the end product to calculate the wastes. They also added the safety pillar to the traditional 5Ss tool [11]. There is shortage of information about the integration of Lean and sustainability in processes. In 2014, Ahuja et al. [24] proposed a framework using Building Information Modeling (BIM) to integrate both Lean principles and Green Rating Integrated Habitat Assessment (GRIHA) evaluation system for the environmental aspect of sustainability (green). According to [24], BIM characteristics allow the integration between lean and sustainability through the project design and construction. The main results were observed through testing the proposed frame work on three case studies. These results took the form of ‘‘problem detection and problem solving ”approach which leads to reduction in rework and delays that subsequently save time and cost. In 2015, Vasconcelos et al. [25] developed a correlation matrix between management actions that elicited from integrating Lean, Green and Wellbeing concepts and the tri bottom line of sustainability in building construction sites. He studied the impact of the integral management strategy on the sustainability of construction sites in three different sites A, B, and C. He concluded that applying the integral management actions offer 79%, 64% and 49% of sustainability on sites representatively. Similarly, Wu et al. [26] compared the effect of Lean, Green and Social Responsibility (LGS) practice separately, in pairs and all together on the sustainability performance of companies in their tri bottom line (economic, environment and social). He concluded that applying Lean practices in firms achieves above medium in Economic and social sustainability and very low in the environmental sustainability. While integrating all of LGS practices get the most benefits compared to implementing each separately, as shown in Fig. 2. He concluded this correlation through an open and semi-structured questionnaire to a three Auto-parts companies in China. The questionnaire was about the implementation of each practice separately and the sustainability performance of the company. In conclusion, most of the researchers studied the ability of lean to achieve sustainability in the construction phase where wastes are measurable and tangible. While there is lack of knowledge in the interaction of those trends in managing of the design phase. In addition all the researchers who claimed the disability of lean to achieve sustainability through the process are biased by the environmental pillar of sustainability, or studied the effect of single lean tool on the one sustainability pillar. While all the studies that study holistically the relation between lean and sustainability concede that lean and sustainability have the same agenda of waste reduction, improvement, and customer’s satisfaction. Where lean focuses on a short term and narrow vision improvement and reduction processes; in which lean seeks reduction in the wastes of the process and the improvement of the process and workforce. In addition lean considers the project stakeholders as its customer. On the other hand, sustainability covers a long term and wide vision of waste reduction and improvement, where It focuses on the long run waste reduction not just a certain process, and the improvement of the whole society and environment. While this environment problem are vanished by researchers suggestion to introduce the environment as one of lean costumer as suggested by [23,8,27].

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Figure 2. The effect of Lean, Green and Social responsibility separately, in pairs and all on the sustainability performance of company [11].

To sum up, the role of lean towards achieving sustainability, whether it takes place intentionally or non-intentionally, is proven clear. On one hand, lean principles could be considered according to findings extracted from extant literature as a subset of the sustainability process. On the other hand, the review concludes that all researchers studied the ability of lean to achieve sustainable benefits. Thus the next part of paper takes another turn which is verifying how implementing sustainability in AEC corporates can match lean principles and philosophy of management. 3. Verification of the relation between lean and sustainability principles This section will verify that applying sustainability agenda in managing AEC process can help in achieving lean construction main principle in the processes of AEC organizations, which is the second objective of this paper. This verification will take place through studying the common attributes between lean construction principles and sustainability. The research adopts the eleven principles of lean proposed by Koskela in his report to Center for Integrated Facility Engineering (CIFE)., as well as the sustainability indicators and guidelines in process of organizations that have been published by Global Reporting Initiatives (GRI).2 3.1. Sustainability indicators Sustainability in operational phase can easily be monitored through the sustainability indicators and certified standards. However, it is different in the management process. So far there are no certain certified standards, but there are efforts to offer guidelines to organizations on how to manage their processes in a sustainable manner. GRI generally publishes guidelines that help organizations achieve sustainability development in their work and reporting their sustainability. This paper relies on the sustainability development guidelines published in the report of GRI under the title of ‘‘A Snapshot of Sustainability Reporting in the Construction and Real Estate Sector” [28]. The researcher chooses this report as it concludes the data from reviewing the sustainability reports of 16 organizations in eleven different countries in the construction and real estate sectors. Thus, most of the guidelines match the AEC industry. This sector will classify the sustainability development guidelines as: 2 GRI is a non-profit organization that was held in 1997. It aims to achieve sustainable development in organizations. It is publishing some general guidelines to achieve sustainability and help in writing the sustainable reports for all industries.

3.1.1. Social indicators The social sustainability in the process focuses on both the labor force and the whole society. (a) Indicators for the participant of the process: – Offer equal employment opportunities and diversity in workforce among Minors, Women, international. – Enrich employee’s skills through training. – Provide a health and safety educational training for staff. (b) Indicators for the whole society: – Develop the concept of employee volunteering, which means to work for the society in working hours. – Allow the participation of the community in the decision making in design phase. – Participation in local community programs (i.e. Donations, Education programs, Building infrastructure for livable communities, or supporting sustainable community development). – Offer Training for the undergraduate or help in the academic researches. – Combat the bribery and corruption in your industrial sector. 3.1.2. Environmental indicators It focuses on the achievement of the environmental sustainability development in the process through reducing all types of wastes in the process and product. (a) Guidelines on design and construction process of the building: – Reduction of the energy use and greenhouse gas emissions generated during the construction process, through reducing the wastes going to landfills, or using different transportation types. – Reduce the pollutant as noise. – Use comprehensive building modeling during design phase (i.e. BIM). – Use Sustainable or renewable energy technologies. – Energy-efficient building design that leads to reducing energy consumption after the building occupation. – Adoption of green construction materials in building design. – Intelligent selection and use of raw materials. (b) Guide lines on managing the whole organization: – Recycling the office material (i.e. papers, cans, etc.). – Offer and monitor the indoor comfort and the environmental quality in the office.

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Economic

Environmental

Social

L11 Benchmark

L9

L10 Flow and conversion Improvement

L8 Continuous Improvement

L7 Focus on the whole process

Transparency

L6 Increase output flexibility

L5 Simplify the process

L4 Reduce Cycle time

L2

L3 Reduce variability

Sustainability Criteria

Stakeholder requirements

Lean Construction Principles

Reduce non value-adding activities (wastes)

principles in design phase

Sustainability Pillars

L1

Table 4 The Interaction Matrix between Lean construction principle and Sustainability criteria in management process.

Consult local people Diversity in teamwork Equal employment opportunities Health and Safety education programs Health exams for staff Enhance employee skills Employee retention Participation in local community programs Intelligent selection and use of raw E1 materials E2 Office recycling for paper, bottles and cans. E3 Reduction of office energy and water usage E4 Minimization of resource wastes E3 Reduced emissions of pollutants Global warming prevention (CO2 E4 emissions) Sustainable or renewable energy E7 technologies Using Green construction material in E8 building design Using Comprehensive building modeling E10 S1 S2 S3 S4 S5 S6 S7 S8

Measure and report your environmental performance E12 Indoor comfort and environment quality E13 Energy efficient design Sustainable values of properties and tracts C1 of land C2 Tax Contribution C3 Use of local resources C4 High return on investment for developers Combating bribery and corruption C5 Creating employment during and after C6 construction C7 Marketing and compotation issues. E11

– Reduction of office energy and water usage. – Measure and report your environmental performance. – Indoor comfort and environment quality.

3.1.3. Economic indicators Economic pillar of sustainability focuses on the role the organization plays towards its own, and the developer’s, profitability and the whole economy in the society as well.

(a) Indicators for the developer and company: – Sustainable values of properties and tracts of land. – High return on investment for developers. – Marketing issues. (b) Indicators for the whole society: – Tax Contribution. – Use of local resources. – Creating employment during and after construction. – Combating bribery and corruption.

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4.3. Economic indicators 4. Findings of the area of interaction between lean and sustainability The advantage of lean principles is its holistic view. The term ‘‘customer” does not comprise the client only, but it should extend to include the end-user and teamwork, as well as the whole society and anyone benefitting from the process or the final product ‘‘building”. Thus the customer, according to lean philosophy in the production process of Architecture project, is the project participant, whether the Client (developer), work force (i.e. Engineers, labors, suppliers, etc.) or the whole society. In addition, the researcher recently ask for adding the environment to the list of customers of lean to achieve more sustainable management process [9,21]. Thus the precise term for ‘‘customer value” that should be used in defining aim of lean instead is stakeholder’s value. Table 4 shows the area of interaction between both lean and Sustainability Principles, whereas refers to the direct impact and refers to the indirect impact. 4.1. Social indicators The Consultation of local people (S1) leads to identifying the end-users’ values from the start point. This subsequently reduces the ability of change after construction that leads to rework (waste) and process improvement, while embodying the principle of transparency. Though the Diversity in team work (S2) does not affect any of lean principles directly, it will indirectly lead to process improvement, which offers feedback from different experiences and points of view. This conclusion is based on the case study that proclaimed that applying continuous improvement in lean can be achieved through checking of the process by another team rather than the original to provide more feedbacks and improvements [28]. Meanwhile, the Equal employment opportunities and Employee retention (S3, S7) will match the stakeholder’s values by regarding the employees as the customer in this part. Similarly, the practice of offering health exams for staff and enhancing the employee skills through training (S5, S6) is one of the employees’ needs; so achieving them helps in achieving stakeholders’ value and will indirectly lead to increase the productivity which is one of the process improvement issues. Participation in local community programs (S8) also helps in achieving the needs and values of the whole society. 4.2. Environmental indicators Most of the indicators of the environmental pillar will not match lean principles unless we consider the environment itself one of the ‘‘Lean” costumers, as mentioned before in chapter 1. In this case, most of the criteria (from E1 to E8, and E13) match the waste reduction and, subsequently, achieves the environment main values. (E10) Using Comprehensive building modeling (i.e. BIM) matches four lean principles due to the characteristics of comprehensive modeling programs as the automatic generation of drawing and editing of information allows all the information all the time and studies the whole process. These advantages achieve the transparency of the process, reduction in the cycle time through focusing on the whole process and improvement of both conversion and flow of information. Measuring and reporting the environmental performance (E11) achieve continuous improvement through getting the feedback and transparency for all the project participant and society. The comparison between the environmental performance and the world which is the base of benchmark will be simplified. Indoor comfort and environment quality (E12) achieve the employee and work force values (L2).

All the economic criteria match the stakeholder value, while in this case stakeholders are the developers for (C4) and the society in all other indicators. In (C3) ‘‘the Use of local resources” as materials or work force is helpful for reducing the transportation or exportation, acting as non-adding value activity in Lean concept. In addition, this will reduce the cycle time of each activity and the whole, and finally simplify the supplying process. By analyzing the previous correlation table, the authors concluded that generally most of sustainability guidelines help to match Lean construction main principle. The sustainability indictor that has the highest interaction with lean construction principles is (E10) ‘‘Using Comprehensive building modeling”, in which it directly interacts with four of the lean construction principles. The sustainability indicator that has the least interactions is (S2) ‘‘Diversity in workforce”, in which it indirectly affects (L11) ‘‘the continuous improvement of the process”. Lean principle that has the highest interactions with sustainability indicators are (L1, L2), which are reducing the non-added value activity (wastes) and Stakeholders’ Values. On the other hand, all the sustainability indicators in tri pillars did not match (L6) ‘‘increase the output flexibility” principle. It is clear that not every single sustainability indicator matches all lean principle concepts. Moreover, if we study the percentage of interaction through dividing the number of all possibilities by the real interaction number, the number of sustainability indicators will be 31, whereas the number of lean construction principle will be 11. Since the total possible interactions are 341 and the real interactions are 46. So the percentage of interaction between sustainability guidelines and lean construction principles is 13.5%. Although it appears to be a low percentage, the practice of analyzing sustainability and lean matching through studying the sum of a single interaction isn’t that accurate. Rather, Consideration of all interactions and benefits should be performed.

5. Conclusions Applying sustainability in management of process and organizations gives equal attention to the quality of life to all stakeholders and the contribution of the process to the society and economy, in addition to environmental conservation. Lean’s main goal is to maximize stakeholder’s value and reduce all wastes to improve the whole process. The correlation Table 4 showed that the sustainability guidelines have an impact on lean principles. Although the percentage of the interaction between lean construction principles and sustainability indicators is 13.5%, lean and sustainability development have nearly common agenda in improving process and stakeholder’s quality of life, reducing all types of wastes, monitoring and self-evaluation for continuous improvement and marketing issues. We should not look at sustainability and lean matching through studying the sum of a single interaction, but we should consider all interactions and benefits at the same time. For the better benefits, however, companies should apply lean and sustainability principles concurrently. Architecture and construction organizations should set their own clear sustainability development goals and initiatives that go beyond the environmental sustainability towards the social and economic sustainability, either in the process or in the product, and focus on the continuous monitoring of their sustainability development through frequent reporting. In this research considering sustainability in the management process of AEC corporates acts as a vital step towards achieving lean philosophy and principles and gain its great potentials.

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FROM LEAN TO GREEN CONSTRUCTION: A NATURAL EXTENSION Isabelina Nahmens, Ph.D.1 1 Assistant Professor, Dept. of Construction Management & Industrial Engineering, Louisiana State University, 3128 Patrick F. Taylor Building, Baton Rouge, LA 70803-6419, e-mail: [email protected]

Abstract One of the focuses of Lean construction is waste elimination from the construction processes, while creating a culture within the company of continuous improvement. Similarly the focus of Green construction is on the removal of waste from the construction process and in addition it adds an environmental dimension to lean construction. Lean and green construction share a common goal, to eliminate as much waste as possible. Therefore, not producing waste is both the most efficient and cost effective approach to sustainability. Current industry practice shows that lean construction is already the dominant paradigm in factory built home manufacturing, yet its impact on the environment is less understood. This paper uses a case study approach which demonstrates that a natural byproduct of applying lean techniques is the reduction of waste which overlaps with one of the key objective of green building. This case study presents the application of lean production in the wall/partition department of a HUD-code home plant which resulted in a 10% reduction of raw material- reducing wallboard damaged during the construction stage. This paper compares material wastes before and after a Kaizen event performed in the wall/partition department. Lessons learned from this case study are discussed and used to proposed guidelines to integrate lean methodology and green building. Findings from this research will contribute to a better understanding of the applicability of lean strategies in the housing industry and its impact on the environment. Introduction The construction industry is one of the biggest contributors to pollution and waste (through its life cycle) (Horvath 2004). As reported by the Environmental Protection Agency (2004), in the U.S., buildings account for 39 percent of total energy use, 12 percent of the total water consumption, 68 percent of total electricity consumption and 38 percent of the carbon dioxide emissions. The construction activities and the built environment have an enormous impact on the natural environment, human health and overall economy. Green building practices can reduce the impact of

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construction on the environment and human health. Green building practices can be introduced at any stage in construction, from design to deconstruction. Ideally, the impact of the built environment should be addressed on a life cycle basis, from the origins of the building material, through the manufacture and installation of these materials, to their eventual demolition of the building. Each stage in this life cycle raises questions of sustainability. Considering that construction waste comprises 40 percent of landfill material (Allen and Iano 2004), it is imperative that builders learn to build in a sustainable manner. Green building principles are a good starting point, by guiding builders to realize the kinds of waste that are generated during the construction stage and how to reduce them. Due to the vast environmental impact of the built environment, the construction industry has a major potential to advance sustainability practices. Combining lean and green building may be one approach to sustainable construction by focusing on waste reduction that not only results in reduced environmental impact but also increases the bottom line by reducing costs. The U.S. Environmental Protection Agency (EPA 2003) found that the implementation of lean strategies produces an operational and cultural environment that is highly conducive to waste minimization and pollution prevention. Although, lean strategies as originally documented by Womack and Jones (1996) do not explicitly incorporate environmental performance metrics, lean production may have a significant positive impact on the environment due to its focus on minimization of resource usage. Current empirical evidence of this link is sparse and has yet to characterize the nature of this relationship. This paper uses a case study example where a HUD-code home manufacturer implemented lean, to explore the impact on the environment, as measured by waste reduction, after the improvement implementation. HUD code homebuilding is an industrialized approach to homebuilding, which relocates many field operations to a more controlled factory environment. HUD code homes are composed of three-dimensional sections that are typically 95% finished when they leave the factory (Carlson 1991), then transported to site, lifted and placed by crane. Due to their production method, HUD code homes produce less waste because of reduced construction time, and less time needed on a site which means less damage to the home site and surrounding environment (Wortman 2007). This paper addresses the construction stage and explores ways to operationalize green building through lean construction strategies for factory-build home manufacturers. More specifically, explores waste reduction strategies in their production operations resulting from lean implementation. Overview of Sustainable and Green Building Sustainable, green and terms alike have become common and part of everyday dialogue among all parties of the construction supply chain- including supplier, factory producers, builders and clients. However, despite the growing use of these terms their definition is in some cases inaccurate and poorly understood. The most widely accepted definition of sustainable construction is from the Bruntland Commission’s report, Our Common Future (Bruntland 1987) which defines it as “development that meets the needs of the present without compromising the ability of future generations to meet their own needs”. In a building context, this definition can

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be applied as: “a building that can be produced and continue to be operated over the long term without adversely affecting the natural environment necessary to support human activities in the future” (Building Science 2006). In order to fulfill this definition, the entire supply chain needs radical changes, not only from a material perspective but also from a production method perspective. Current construction methods are very far from producing truly sustainable buildings, however moving towards those goals is possible. Considering how far the construction industry is from building a truly sustainable building, a practical definition of green building is one that is more sustainable than current practices (Building Science 2006). EPA (2008) describes green building as the practice of creating structures and using processes that are environmentally responsible and resource-efficient throughout a building's life-cycle. Green building relates to sustainable development, as it promotes building practices that conserve energy and water resources, preserve open spaces through brownfield development, and are accessible to public transportation (EPA 2008). Integration of Lean and Green Building The lean production system has its origins in the automobile manufacturer industry with the Toyota Production System (Ohno 1988). Lean means getting the right things, to the right place, at the right time, in the right quantity while minimizing waste and being flexible and open to change (Womack 2005). The overriding goal of a lean production is to deliver value to all stakeholders- internal and external customers; and to eliminate waste- all activities that do not add value. Lean production is based on five fundamental principles: 1) identify what the customer values, 2) identify the value stream and challenge all wasted steps, 3) produce the product when the customer wants it and, once started, keep the product flowing continuously through the value stream, 4) introduce pull between all steps where continuous flow is impossible, and 5) manage toward perfection (Womack and Jones, 1996). In Construction the application of the lean production model stems from a discussion of Koskela’s work (1993), which emphasized the importance of the production process flow, as well as aspects related to converting inputs into finished products as an important element to the creation of value over the life of the project. Kaizen, typically referred to as an event, is an intensive and focused approach to process improvement. This lean method seeks operational perfection by eliminating waste – non-value added activities from the perspective of the customer. Green building can be operationalized by using a Kaizen approach and focusing on environmental performance of the production processes. Conducting a Kaizen event helps to eliminate waste by empowering employees with the responsibility, time, and tools to uncover areas for improvement and to support change. This type of activity is team based and involves employees from different levels of the organization. Traditionally, the purpose of the Kaizen event is to continuously improve and install a lean culture in the company through the use of lean principles and tools. A typical framework for executing a Kaizen event is shown in Figure 1.

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Identification of Waste. After initial data collection and observations the lean team concluded that the wall build department was a bottleneck to the main line flow and restricted overall plant capacity. The identified source for this issue was the incapability of the wall build area to consistently keep pace with the main production line or takt time (the takt time on the main line was 48 minutes, while the cycle time of the wall build department was 65 minutes). The takt time is a representation of customer demand. The lean team also observed various forms of waste, including labor, equipment and material, in the wall build process. Most of the waste identified was due to the poor layout, which affected the overall performance of the production system, in particular the activities in the wall build department. As evidence from Figure 2, flows within the build area went in every direction, many were lengthy, and they often crossed other flows, creating congestion. Process Description. This case study focused in the activities related to the wallboard, because results from lean implementation showed great potential for material waste reduction. Before the kaizen event, material handlers delivered the raw material by loading the bundles of wallboard onto the roller bed or on the floor. Workers in charge of prepping the raw material (e.g. supporting activities) retrieved the wallboard from the bundles staged on the roller bed or on the floor nearby. They carried the wallboard to one of two saws or to a slitter. The jig table of the saw/slitter was set at the specified size and wallboard was cut to size, labeled by hand, and placed in an adjacent staging cart. Workers on the framing tables selected a panel to build, obtained the drawing and retrieved framing components from the staging cart. After framing the wall, they then retrieved the pre-cut wallboard from the staging cart, positioned it on the frame and attached it to the frame using an adhesive gun and staples. The completed panels were then staged upright adjacent to the tables awaiting transport to the line, sometimes blocking the access to the wallboard roller bed (Figure 3). Completed walls were moved to the line by two methods, depending on location of the framing table. Panels staged next to the lower tables were transported by bridge crane, while panels staged next to the central tables were dragged along the floor by hand. The second method increased the chances of damaging the installed wallboard.

Figure 3. Wallboard Roller Bed Blocked by a Finished Wall

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Key Waste Drivers. The overriding issue with the wallboard activities was the poor layout of the wall build area and improper staging equipment. Although, the area had a wallboard roller bed, which was the designated area to properly stage the raw wallboards, it was not fully used because of limited accessibility. The rollers on the roller bed were designed to pull material from the ends and not from the sides as required by the current layout. In addition to the orientation of the rollers, the second level on the roller bed made the retrieving of the raw material awkward (since required workers to pull material over their heads). Because of these limitations, material handlers often staged bundles of wallboard on the floor in any open space. Further congesting and blocking path ways in the area and increasing chances for material damages. The staging area for the pre-cut wallboard was close to two framing tables, but further form the other two and framers had to travel longer distances and maneuver with load through other workstations to retrieve materials. This situation increased the chances of damaging wallboards. Before conducting the Kaizen event, workers were not aware about how much wallboard was been wasted due to improper staging or awkward maneuvers through the poor layout. This fact was discovered during the Kaizen event. The Solution. The objective of the wall build-Kaizen event was to rearrange the layout to improve process flow as shown in Figure 4. Some of the layout changes accomplished in the Kaizen event included (Nahmens and Mullens 2009): • The two central framing tables were moved and aligned with the lower two tables, allowing finished walls to be staged so that they were accessible by the bridge crane that was used to deliver finished walls to the main line and reducing the potential damage of installed wallboard. • The stud cutting activity was rearranged to achieve a straight-line flow. The lumber storage rack was relocated on the upper wall to provide in-line flow for the material handler during delivery. Two chop saws were turned 90 degrees and relocated directly below the storage racks. New pre-cut component staging bins were located directly adjacent to the framing tables (each bin can hold studs for up to ten panels). Sawyers place cut components directly in the bins, eliminating the need for framers to leave their tables to obtain components. • Wallboard cutting was rearranged to smooth flow. Raw material was staged in a new rack that held six different colors of wallboard, two different sizes per color. The new rack is easy to replenish from the front and puts less strain on cutters as they pull material and transport it to the cutting tables (e.g. pulling over their heads). The saws/slitter was relocated away from the traffic path, facilitating wallboard handling. A dumpster was placed immediately behind the saws/slitter for scrap. Next to the saws/slitter a staging area for the cut wallboards was designated. • Half of an existing mezzanine, used for insulation storage, was moved to open up floor space for the improved layout.

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lean (e.g., efficient continuous flow, effective pull system, workload leveling, defect-free processes, standard tasks, good visual controls, and reliable technology) were also good concepts for material waste reduction. As a whole, the implementation of lean strategies were shown to increase efficiency and reduce variability of building operations, concurrently resulting in material waste reduction a key objective of green construction. Guidelines: Lean and Green Building Findings from the case study are summarized in the following set of guidelines to integrate lean construction methodology and green building, while minimizing material waste. 1) Move related equipment and materials closer together. Utilize straight line, L or U-shaped flows, to encourage efficient movement of people and materials. From a lean perspective, this reduces travel waste such as excessive travel time, and congestion delay. From a green building perspective, it reduces the possibilities of related damage of raw material, work in process and completed components. This strategy can be used in all the departments across the plant. 2) Designate and label each area within the production floor, forcing the material handler to stack bundles of raw material in the designated rack or staging area, since there is no unused space - all space is assigned to other activities or designated as traffic paths. From a lean perspective, this facilitates the process flow, standardizes the process and generates a lean culture among workers. From a green building perspective, ensures sustainability of the green improvement gains in the process related to waste reduction from the kaizen event, and minimizes wasted spaces. 3) Use proper staging equipment that has easy access to replenish and retrieve material from, putting less strain on workers. From a lean perspective, proper stating equipment makes the process more efficient. From a green building perspective, reduces the possibilities of damage of material due to awkward maneuvers (e.g. pulling over their heads or against rollers) thus reducing rework waste. Conclusions The transition to a sustainable society is not a trivial problem but rather a complex endeavor. The construction process and the built environment represents a challenge in this transition, which is likely to intensify given the increasing trends in population and the aging infrastructures around the world. This paper explores the applicability of lean strategies in the housing industry aiming to reduce material waste and encouraging resource efficient processes. In general, there are some benefits to be realized from the use of some lean principles as an approach to lessen the environmental impact of construction activities. These results reflect the similarities of both green building and lean production as far as their goal to reach resource efficient operations- reducing waste. Environmental factors should be an integral part of how business is conducted, not an afterthought or an add-in. Work processes are inherently environmentally friendly or hazardous for the environment according to the environmental hazards present in each step required to complete the construction

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process. By carefully planning processes to minimize environmental impact, building processes can be made greener. In order to transition to a true sustainable society, requires designers and builders to understand the problem and modify their construction processes and business strategies. Only in this way current building process can be improve, and our society can head towards a sustainable future. References Allen, E. and Iano, J. (2004). “Fundamentals of Building Construction, Materials and Methods”. Fourth Edition, Publisher John Wiley & Sons Inc, New York, NY. Bruntland, G. (1987). "Our Common Future: The World Commission on Environment and Development". Oxford, Oxford University Press. Building Science (2006). “BSD-005: Green Building and Sustainability”, last updated 2006/10/27. Retrieved August 21, 2008, from BuildingScience.com Carlson, D.(1991). “Automated Builder: Dictionary/Encyclopedia of Industrialized Housing”. Automated Builder Magazine, Publications Division, CMN Associates, Inc., Carpinteria, CA. Chatterjee, B. (2008). “Applying Lean Kaizen: A catalyst for organization change”. Pharmaceutical Processing. Feb2008, Vol. 23 Issue 2, p10-14. Horvath, A. (2004). "Construction Materials and the Environment". Annual Review of Environment and Resources. Vol. 29, pp. 181-204. Koskela, L. (1993). “Lean production in construction”. Proceedings of the 10th ISARC, Houston, Texas, May 24-26, 47-54. Nahmens, I. (2007). “Mass customization strategies and their relationship to lean production in the homebuilding industry”. Unpublished doctoral dissertation, University of Central Florida. Nahmens, I. and Mullens, M. (2009). “The Impact of Product Choice on Lean homebuilding” Construction Innovation Journal, January 2009, Volume 9, Issue 1. Ohno, T. (1988). “Toyota Production System”, Productivity Press. Salem, O. and Zimmer, E. (2005). “Application of lean manufacturing principles to construction”. Lean Construction Journal, Volume 2, Number 2. U.S. Environmental Protection Agency (2003).“Lean Manufacturing and Environment. http://www.epa.gov/lean/performance/index.htm (Last updated on Tuesday, March 4th, 2008). U.S. Environmental Protection Agency (2004). “Buildings and the Environment: A Statistical Summary Compiled by: U.S. Environmental Protection Agency Green Building Workgroup”. December 20, 2004. U.S. Environmental Protection Agency (2008). “Lean in Government Starter Kit”. Last updated on Wednesday, April 16th, 2008. http://www.epa.gov/lean/toolkit/LeanGovtKitFinal.pdf (Retrieved August 21, 2008). Womack, J.P. (2005). “Lean Consumption”. Harvard Business Review, March 2005. Womack, J.P. and Jones, D.T. (1996). “Lean Thinking: Banish Waste and Create Wealth in Your Corporation”. Simon & Shuster: New York, NY. Wortman, R. (2007). “Modular Homes Lead Industry Green Building Efforts”. Ezine Articles, submitted October 19, 2007. (Retrieved August 21, 2008).

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Lean Construction and Sustainability Complementary Paradigms? A Case Study Alexandra Rueff Vieira1, Nuno Cachadinha2 Abstract In times when Sustainability is a major concern in public opinions all around the planet, it has become a constant issue for most Industries. The Construction Sector is not an exception to this trend, and efforts have been reported on seeking to adopt metrics that can measure Sustainability on site. On the other hand, the concept of Lean Construction (LC) is becoming a reality more and more present in this sector. Its effectiveness in controlling and eliminating wastes are becoming more and more acknowledged. Both concepts appear to have significant principles in common, hence this paper intends to examine and establish a relationship between LC and Sustainability, and assess their complementarity. This paper portrays a case study where LC tools and techniques where applied on a construction site, in order to observe and assess the relationship and complementarity between those and the Sustainability Construction Index (SCI) developed by a major Portuguese Construction Company, Soares da Costa Construções, S.A. (SDC). KEY WORDS Lean Construction, Sustainable Development and sustainable metrics, Portugal, Sustainability Introduction The concept of sustainable development was coined in the 1987 Brundtland Report as “development that meets the needs of the present without compromising the ability of future generations to meet their own needs” (UN, 1987). This document is part of a sequence of initiatives that support a critical point of view of the development model adopted by industrialized countries and reproduced by developing nations. The report points out the incompatibility between sustainable development and the present patterns of production and spending. Following the publication of this report, other conferences were held in which other documents were created, but all with the same objective, to contribute to the sustainability of a nation. This goal sparked all sectors to the need of introducing the concept of sustainability and sustainable development.

1

MS.c Student, Departamento de Engenharia Civil, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Monte da Caparica, 2829-516 Caparica, Portugal, Phone +351 914681379, xanarueff@ gmail.com 2 Assistant Professor, UNIDEMI, Departamento de Engenharia Civil, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Monte da Caparica, 2829-516 Caparica, Portugal. Phone +351 212948557, [email protected]

Safety, Quality and Environment

612 Alexandra Rueff Vieira, Nuno Cachadinha

In the business sector, a number of organizations have recently focused on Corporate Sustainability and Corporate Social Responsibility begins to emerge in a growing way, indicating the integration of the concept of sustainability by this sector. The first traces of sustainability logics in business companies have thus occurred by reporting environmental, social and even sustainability progress (Pinheiro, 2006). The construction sector has not been indifferent to this process of integrating sustainability. It is, by nature, a sector that tends to be resource-intensive and a largescale waste producer, which often produces significant impacts on the environment (Pinheiro, 2003). This large-scale waste production needs to be taken seriously. According to Grohmann (1998), the amount of materials and manpower wasted in three construction sites allow the construction of another identical project, i.e., the waste would reach a rate of 33%. These wastes are reflected in the work costs that can cause a 6% increase in total cost (Pinto, 1995). Against this backdrop, LC came to change the production management system in the construction sector. This concept aims at eliminating all types of wastes, such as costs, time, materials or equipment in order to reach a better final product, thus increasing customer value. This paper aims at contributing to the assessment of the relationship and complementarities between Sustainability and LC concepts and principles. A review of previous literature of both areas of knowledge is carried out. Lean concepts and solutions are then presented and their possible contribution to Sustainability discussed. A case study is then portrayed where LC tools and techniques were applied on a construction site, in which practical observations were conducted, utilizing the Sustainability Construction Index (SCI) developed by a major Portuguese Construction Company. Finally, conclusions are drawn and future research is proposed. Literature review Sustainability in business sector According to Cepinha (2007), “All companies, regardless of the sector in which they operate, have a very important (moral) role in contributing to the sustainable development of the planet”, thus it is necessary to incorporate the concept of sustainability into planning systems corporate management. Sustainability principles have been materializing in the form of voluntary certification systems, such as the LEED system in the USA, the BREEAM system in the UK and the LiderA system in Portugal. They share, as common basis, the Triple Bottom Line (TBL) approach; social, economic and environmental. To prove that a company fits the 3 principles of the TBL in its planning, variables have to be measured and the results compared. This resulted in the need to search for ways of linking sustainable performance to company value increase. The result of this demand has been the development, in 1999, of the Dow Jones Sustainability Index (DJSI). This was the first global reference to impartially supervise the financial performance of sustainability leaders on a global scale (Dow Jones Sustainability Group Index, s/d). That same year, another index linked to sustainability was developed, called

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FTSE4Good. It influences investment decisions and defines how companies are evaluated (FTSE - The Index Company, s/d). Aware of this trend, construction companies have been adopting existing sustainability indices or developing their own. In the Portuguese construction sector, Soares da Costa has, since 2008, been developing and implementing a tool that monitors the sustainable performance of their work sites, the Sustainability Construction Index (SCI). This tool was developed by a multidisciplinary team, composed by several elements with different functions inside the company, with the aim of monitoring the impacts of the works site and their performance minimizing negative impacts of economic, social and environmental activities, by seeking to transform good practices in common practices (Soares da Costa, 2010). The SCI is divided into 3 indicators: Environmental Performance, Systems Management, and Economics and Value Chain, in which each is composed by subcategories as shown in the table 1. Table 1: Indicators evaluated in SCI (adapted from Soares da Costa, 2010) General Work Site Indicators Environmental Performance Indicators Systems Management Indicators

Economics and Value Chain Indicators

Workers on site; Worked Hours; Amount Budgeted for Environmental Planning and Management of Health and Safety Total Energy Consumption; Total Water Consumption; Total Water Reuse; Total Waste Production, detailed by type of final destination; Material Reuse; Land Volume/Excavated Soils Total, detailed by type of final destination Accidents Indexes (Frequency and Severity); Awareness / Information / Training Environment; Awareness / Information / Education in Health and Safety at Work; Awareness / Information / Training on Quality; Costs Management and Environmental Management Health and Safety at Work ; Number of Environmental, Health and Safety and Quality NonConformances ; Number of Health and Safety at Work Non-Conformances ; Number of Quality Non-Conformances Community Investments - Total; Local Suppliers - Volume of Purchases; Fines and Penalties – Financial amount; Internal Social Actions; Number of Workers’ Claims; Monthly Value of Production

Lean and Sustainability From a positive perspective, the construction sector is one of the largest and important industrial sectors. But it is simultaneously of the largest polluters (Horvath, 2004, cited in: Bae and Kim, 2007). Therefore, the construction industry has a great potential for

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promoting sustainable development. One of the possible approaches to this promotion it is implementing LC principles through the introduction of social and environmental values as new targets to achieve, rather than focusing on just accidental benefits of LC to the environment (Bae and Kim, 2007). Bae and Kim (2007) describe in their work how LC methods can contribute to the sustainability of a project. Table 2 summarizes these methods; more specifically it indicates which Lean tools can contribute to the sustainability of a project. Table 2: Main contributions of Lean tools in sustainable development Tools JIT

5S VSM

Kaizen

Main contributions for sustainable development Tool that may or may not be environmentally friendly; Reduces the amount of materials and materials’ damages; Reduces the sources that cause the extra stock; However, the frequent stock transportation associated could cause increased emissions Visual tool that could help in sustainable construction; Used to maintain a workplace clean and organized Visual tool that shows the processes (products and information); Allows for a better understanding of the generation of value streams and the steps which enclose waste; this tool can be used not only for economic purposes, but also for social and environmental ones, by adding environmental information to the map “Continuous improvement”, in Japanese; It has a key role in improving the current state towards sustainable development; All sustainability indicators could be improved by Kaizen

On a more conceptual level, Martinez et al., (2009) apply the principles of Morphologic Analysis and Cross-Impact Matrix, in order to find the relations between Lean and Sustainability concepts. This study developed a methodology of conceptual integration that has allowed sequentially disposing several construction activities in different scenarios within the life cycle of a construction project. Lean Tools As the theory supporting Lean Thinking developed, a number of techniques that allowed its principles to be put into practice were created, developed and adapted. These Lean tools are numerous and their main objective is to certify on site what the theory itself says,  i.e.,  eliminate waste and  streamline  processes  and resources. Seven of those Lean tools were considered particularly adequate for the materialization of the TBL and were looked at closely. They are listed and described below. Value Stream Mapping (VSM) This is a planning and communicating tool that enables to manage the material and information involved in the process. Rother and Shook (1998) presented standardized icons that make it easier to understand and apply this tool. It is composed of 5 steps

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(Queiroz et al., 2009): identify a product, draw the current VSM, proposals for improvement, create the future VSM and implement and monitor the changes. This tool is very practice oriented and it is basic for the evaluation of where and how in the production process other Lean tools and techniques can be applied. 5S This is a set of Japanese techniques consisting in 5 steps that aim to organize and standardize the work environment: SEIRI (Sense of use): Distinguishes  useful from  not  useful  materials  and tools, eliminating the unnecessary. SEITON (Sense of organization): Refers to the organization of materials and tools. This organization aims at the identification and placement of tools, materials and equipment in the right spot, in order to allow a quick and easy access to them. SEITO (Sense of cleaning): It consists of keeping the work area, surfaces and equipment clean and restoring and checking whenever it is necessary. It must be a daily procedure in order to achieve a working environment constantly clean and organized. SEIKETSU (Sense of standardization): It seeks to define  standard procedures  to maintain the working environment clean and organized. SHITSUKE (Sense of self-discipline): It has the aim of developing self-discipline by maintaining the utilization of all the steps mentioned above in a continuous way. Just in Time (JIT) The main objective of this tool is to produce the right amount at the right time with the right quality level (Chan, 2001). It is the ideal tool to fight one of the seven wastes identified in MUDA: Stock excess. MUDA is composed by seven types of wastes identified by Taiichi Ono including: overproduction, transportation, excess motion, waiting, inappropriate processing, stock excess and defects. Last Planner® and Percentage Plan Compete (PPC) It essentially refers to the short and medium term planning and control, in which the main objective is to ensure, through various procedures and tools, that all the prerequisites and constraints of an activity are solved at its beginning, allowing the activity to be carried out without disruption and being completed according the planning (Peneirol, 2007). The PPC is an index that calculates the percentage of activities completed each week, which should follow the Last Planner® (Ballard and Howell, 1998c). Map of Irregularities This map was adapted from the Map of Fault proposed by Mendonça (2008) and it consists in completing the information obtained from the PPC, i.e., every time an

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activity is given as non-completed, the cause of failure is analyzed and recorded on this map. The map indicates the type of work and the week, in which the assessment is made, it identifies the activities that have not been completed, the detected failure and its consequences and finally the suggested resolution. Subcontracting Relationship In recent years, the practice of outsourcing has been increasing and it often encompasses for about 90% of the total project (Hinze and Tracey, 1994). Since close relationships between firms can improve the performance of the construction process, as well as eliminate waste and reduce efforts, evaluating this performance has become an important factor (Vrijhoef and Koskela, 2001). Kaizen This Japanese word’s meaning is continuous improvement. It is based on the concept of a cyclical process which can involve people, materials or equipments which seeks to improve the processes performance involving all activities. Kaizen is a methodology that seeks to achieve perfection. REsearch method This research study was carried out on a construction site from SDC, with the aim of establishing a relationship between LC and the company’s SCI. To establish those relations, Lean tools were applied in construction processes in order to optimize them. The site was directly observed during a period of 1 month, in which a data collection was carried out through direct observation, document analysis (made available by the company), meetings on site with the heads of the project. The methodology used is based on the 5steps that compose the VSM: • Identify a product or service that will be subject to the implementation of improvement proposals. In this study case, 3 processes were chosen: Plasterboard, steel and formwork material. These were the activities with the highest financial and workload weight. • A current VSM was drawn for each of these 3 processes, describing all the steps that constitute each of the 3 processes, from the moment the order of the material is made to the collection of the waste that resulted from these processes. • An analysis was carried out to the 3 current VSM, in order to identify weaknesses in the process and non-value-adding steps. Improvement proposals were made to eliminate the weaknesses and Lean tools were selected that best fit the proposed solution. • The future VSM was then drawn based on the proposals made in the previous step, and providing the bases to implement these. • Finally, the fifth step is based on the proposals’ implementation and monitoring. During the implementation, difficulties that may arise must be taken into account, creating a new VSM in order to achieve continuous improvement.

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The conclusions drawn were then validated through in depth interviews with the company’s technical general director, its general production director and the senior officer that lead the development of the company’s SCI, as well as the supervision of its implementation in the job sites. This validation strategy results from the particular characteristics observed in this case study and will be described and justified in the next section of this article. Main Results and Discussion During the analysis made to the 3 current VSM, some steps of the processes were identified as already optimized. This situation was found not only in these 3 processes, but also in steps belonging to the planning and preparation of the work site. Following the Kaizen methodology, improvement proposals were made to some isolated weaknesses detected in the previous processes. Interestingly enough, these optimized steps showed several characteristics that were compliant to Lean principles, indicating that optimization efforts had already been taken, intuitively utilizing Lean principles. This observation led the authors to compare the SCI of this job with the overall average in the company. Although the data compiled by the company was still preliminary, this job’s performance was found to be above average. This was in line with the observation that the job’s staff put particular care in optimization issues. Due to these particular characteristics there was little room left for further improvement in this specific project. This led the authors to carry out a reverse validation strategy. The improvement proposals were brought together in a set of tables, which were then presented to technical general director, its general production director and the senior officer that lead the development of the company’s SCI. This was carried out in meetings held at the company’s office in Lisbon, with two separate objectives: the improvement proposals were to be validated, and the optimized procedures which intuitively included Lean principles were to be analysed, in order to determine whether they were common procedure at the company or if they were only being applied in this specific job site. The in depth interviews carried out determined that most of the optimized procedures were specific to this job site. This was due to the joint effect of three reasons: the owner was known for being strict about time or cost overruns and environment conscious, the contractor’s staff on site were known inside the company for placing great interest in process optimization and the scarcity of space available for the staging area. Thus, it was concluded that having a demanding owner/client and rigorous deadlines and budgets is an important motivator for the adoption of Lean methods and tools.

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Since the aim of this work was to establish a relation between Lean principles and Sustainability, table 3 below was prepared based on the information and results obtained. This table identifies the processes/steps, the Lean term and the corresponding SCI metric, indicating also the possible relations between these two concepts. Table 3: Parallelism between Lean and Sustainability  

Step

Lean Term

SCI metrics

Plasterboard

Material displacement for the application site

MUDA and 5S

Accidents Indexes (Frequency and Severity)

Formwork material

Placing of waste containers in the immediate vicinity of the shuttering/striking works

5S

Plasterboard

Send waste to appropriate location

Steel

Option to buy pre cut and shaped steel

Eliminating activities insitu

Waste collection

5S

Definition of durations and their maturities

Last Planner and PPC

Linking PPC to the Map of Irregularities

Kaizen

Subcontractor hiring

Subcontractor relationship

Plasterboard

Planning Work planning and Site Management

Accidents Indexes (Frequency and Severity), Nonconforming HSW and Total Waste Production

Total Waste Production

Monthly Production Value

Table 3 was discussed with the senior officer in charge of the SCI development, in order to determine whether the measures portrayed procedures have any impact on the SCI metrics obtained for this job, when compared with the average SCI metrics in tall the job sites of the company. According to this responsible, due to the recent development of the SCI metrics, which started in 2008, it is not yet possible to determine whether these procedures have any impact on the SCI metrics at this stage. However, it is the company’s objective to develop the SCI to the point of being able to determine which procedures impact it, and determine if it is a positive or negative impact. The analysis made aimed at establishing a connecting bridge between Lean principles and Sustainability metrics. Each of these steps is analysed and presented bellow and they will be identified if they were an existing procedure present in the construction or an improvement proposal made. In the first step (existing procedures), it was possible to establish the elimination of two types of wastes identified by MUDA (excessive transportation and handling) and the use of the 5S methodology (work area organized). From a Lean Thinking perspective, the benefit obtained was an increase of the workplace safety, which should lead to a decrease in the number of accidents. There is a SCI metric that counts the

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number of work accidents, called Frequency Index. It was then possible to establish a relationship between this metric and a Lean procedure. The second (proposal made) and third (existing procedure) steps correspond to the use of the 5S methodology. The benefits resulting from this procedure are an increased workplace safety and its easier reading by the workers, which translates into safer work conditions for manpower. These procedures should lead to a decrease of nonconformances, number of accidents and to a faster and more effective waste disposal. The SCI presents metrics that quantify those parameters: Non-conforming HST, Frequency Index and Production Waste (differentiated by type of final destination). Thus, a relationship was established between these procedures and metrics. The fourth (proposal made) and fifth (existing procedure) steps correspond to the elimination of some in-situ activities and the use of the 5S methodology. The aim of the fourth step proposal was to eliminate the workspace problem, since the steel yard was located on top of a 2-story building. With this measure, the waste coming from the steel work would be also eliminated. Both procedures lead to a decrease in waste quantities and a faster and more efficient waste collection and disposal. SCI has a metric called Waste Production that quantifies the waste dispatch, reuse and disposal on site. Thus a relationship was identified between both metrics and procedures. The last three steps correspond to the use of the Last Planner® and PPC (existing procedure), Kaizen (proposal made) and Subcontractor Relationship (existing procedure). These three procedures lead, each in its own way, to a better work environment and better planning, increasing the productivity on site, with positive reflects on present and future work progress and development. Hence a relationship was established between them and the SCI metric, “Monthly production”, which measures the monthly value produced. Conclusions In this work it was possible to conclude that there is a relationship between Lean and Sustainability. Through the application of Lean tools in the construction processes of a case study, it was possible to establish a parallelism between SCI metrics and Lean. The proposed model was developed based on the VSM’s 5 steps, since it was identified as having potential to contribute to sustainable development. Once the material flows were drawn and the non-value-adding steps identified, the future state VSM was created, which served as a basis to implement the proposed solutions. A relationship was then established between the proposals and the SCI metrics. Quantifying this relationship depends on two important factors: • A successful model implementation that requires time, initial investment and change efforts; • A successful SCI implementation and consolidation that requires time and dedication from all players. Being  faced with a  growing  competition  between  companies  in the construction sector and a growing awareness of the need to adopt a sustainable development within businesses is expected, with this model and with this established relationship, open new ideas and gateways between other Sustainability metrics and Lean.

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Future Research Fields In order to complete this work, determining and quantifying the impact of Lean on SCI metrics, once both this index and the measures proposed in this study are fully implemented in the company and have become standard procedure. Once this stage is reached, a cost-benefit analysis of the implementation of the proposed measures would also be of great interest.. Another study of great importance should lead to the combination of Lean and Sustainability and their integration in the whole of the company’s construction procedures, so that the whole construction process would be optimized both from a Lean perspective (minimizing waste, maximizing value to the customer) and in terms of Sustainability performance, maximizing the TBL. Acknowledgements The authors wish to acknowledge the cooperation of Soares da Costa Construções, S.A., for providing access to their SCI and to the case study project, as well as assistance on several occasions in the course of this study. References Bae, J.W., Kim, Y.W. (2007). “Sustainable Value on Construction Project and application of Lean Construction Methods.” Proceedings Internacional Group for Lean Construction (IGLC)-15. Michigan, USA. Ballard, G., Howell, G. (1998c). “Shielding production: essential step in production control.” J. of Constr. Engrg. and Mgmt., 124 (1) 11-17. Cepinha, E. (2007). “A Certificação Energética de Edifícios como Estratégia Empresarial do Sector da Construção - Análise à escala nacional.” Ph.D. Diss., Envir. Engrg., Instituto Superior Técnico, Portugal. Chan, F.T.S. (2001). “Effect of kanban size on just-in-time manufacturing systems.” J. of Materials Processing Technology, 116 (3) 146-160. Dow Jones Sustainability Group Index, w/d. http://www.sustainability-indexes.com/ (4/1/2011). FTSE - The Index Company, w/d. http://www.ftse.com/ (4/JAN/2011). Grohmann, M.Z. (1998). “Redução do Desperdício na Construção Civil: Levantamento das Medidas Utilizadas pelas Empresas de Santa Maria.” VI Congress Internacional of Industrial Engineering. Univ. Federal FluminenseUFF, Brazil. Hinze, J., Tracey, A. (1994). “The Contractor-Subcontractor Relationship: The Subcontractor’s View.” J. of Constr. Engrg. and Mgmt., 120 (2) 274-287. Horvarth, A. (2004). “Construction Materials and the Environment.” Annual Review of Environment and Resources, 29 181-204. Martinez, P., González, V., Da Fonseca, E. (2009). “Green-Lean conceptual integration in the Project design, planning and construction.” Rev. Ing. Constr., 24 (1) 0532. Mendonça, T.C.P. (2009). “Desenvolvimento e aplicação de metodologias lean na construção.” Ph.D. Diss., Civil Engrg., Univ. de Aveiro, Portugal.

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Peneirol, N. (2007). “Lean Construction em Portugal – Caso de estudo de implementação de sistema de controlo da produção Last Planner.” Ms.C. Diss., Civil Engrg., Instituto Superior Técnico, Portugal. Pinheiro, M.D. (2006). “Ambiente e Construção Sustentável.” Amadora: Environment Institute, Portugal. Pinheiro, M.D. (2003). “Construção Sustentável – Mito ou realidade.” VII Congress National of Environment Engineering, Lisbon. Pinto, T.P. (1995). “De volta à questão do desperdício.” Construction, 271 34-35. Queiroz, J.A., Rentes, A.F., Araujo, C.A.C. (2009). “Transformação enxuta: aplicação do mapeamento do fluxo de valor em uma situação real.” Hominiss – Excellence in Production Engineering. (available at http://www.hominiss.com. br/publicacoes.asp). Rother, M., Shook, J. (1998). “Learning to See – Value-Stream Mapping to Create Value and Eliminate Muda.” The Lean Enterprise Institute. Massachusetts, EUA. Soares da Costa (2010). “ISO - Índice de Sustentabilidade em Obra.” Seminar Metrics of Sustainability, Goethe - Institut, Lisbon. UN - United Nations (1987). “Report of the World Commission on Environment and Development: Our Common Future (Chapter 2).” World Commission on Environment and Development. Paris. Vrijhoef, R., Koskela, L. (2000). “The four roles of supply chain management in construction.” European J. of Purchasing & Supply Mgmt, 6 (4) 169-178.

Safety, Quality and Environment

Lean Principles: An Innovative Approach for Achieving Sustainability in the Egyptian Construction Industry Ayman A. E. Othman

Mayar A. Ghaly

Nazirah Zainul Abidin

Architectural Engineering Department, Faculty of Engineering, The British University in Egypt (BUE), El Shorouk, Cairo, Egypt [email protected]

Architectural Engineering Department, Faculty of Engineering, The British University in Egypt (BUE), El Shorouk, Cairo, Egypt [email protected]

School of Housing, Building and Planning, University Sains Malaysia, USM 11800 Penang, Malaysia [email protected]

In spite of the economic and social contributions of the Construction Industry (CI) in terms of achieving national and international development plans, offering employment opportunities, increasing Gross Domestic Product (GDP) as well as providing community members with buildings and infrastructure projects that meet their needs and fulfil their requirements, it has a major impact on the environment. The construction industry is a very large consumer of non-renewable resources. In addition, it is a significant source of waste and pollution of air and water as well as an important contributor to land dereliction. Furthermore, it is responsible for 50% of the material resources taken from nature, 40% of energy consumed and 50% of total waste generated. Towards saving the planet, it became crucial to stop the depletion of the natural capitals of the earth thorough developing creative and innovative solutions that achieve the objectives of present generations without compromising the ability of future generations to meet their own needs. This paper aims to investigate the role of Lean Principles (LPs) as an innovative approach for achieving sustainability in the Egyptian Construction Industry (ECI). Towards achieving this aim, a research methodology consisting of literature review, case studies and survey questionnaire, is designed to accomplish five objectives. Firstly, reviewing literature related to sustainability, (LPs) and highlighting their relationship as well as discussing the ability of (LPs) to achieve sustainability objectives. Secondly, presenting and analysing four case studies benefited from applying (LPs) to deliver sustainable projects. Thirdly, presenting and analysing results of a survey questionnaire directed to a sample of Egyptian Construction Firms (ECFs) to investigate their perception and application of (LPs) towards achieving sustainability objectives. Fourthly, developing a conceptual framework to promote the use of (LPs) as an innovative tool for achieving sustainability in (ECI). Finally, summarising research conclusions and recommendations useful to governmental authorities and construction professionals.

DOI 10.5592/otmcj.2014.1.2 Research paper

Keywords Sustainability, Lean Principles, Construction, Case Studies, Egypt

a. a. e. othman

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m. a. ghaly

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zainul abidin

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l e a n p r i n c i p l e s : a n i n n o v a t i v e a p p r o a c h f o r a c h i e v i n g . . .· pp 917 - 932

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INTRODUCTION In terms of its activities and outputs, the (CI) represents an integral part of the social development and economic growth of both developed and developing countries (Field and Ofori, 1988; Mthalane et al., 2007). Socially, it aims to fulfil community needs through providing users with facilities for housing, education, culture, medication, business, leisure and entertainment. In addition, it constructs infrastructure projects comprising roads, water and electricity stations as well as telecommunication networks to enable these projects to perform their intended functions effectively (Friends of the Earth, 1995). Economically, Lowe (2003) stated that the value added of construction to the country’s Gross Domestic Product (GDP) is in the range of 7% to 10% for highly developed economies and around 3% to 6% for underdeveloped economies. The construction outputs can be classified as a major component of investment and part of fixed capital; both are essential factors for a continuous economic growth. Furthermore, governments frequently use the (CI) as a driver to manage the local/national economy through increasing public expenditure to overcome the impact of recession and decrease the ratio of unemployment (Ball and Wood, 1995). On the other hand, the (CI) is criticised for having negative impacts on the environment. It is a very large consumer of non-renewable resources, a substantial source of waste and pollution to air and water. According to a study conducted by the U.S. Energy Information Administration (EIA) in 2011, the building sector consumes nearly half (48.7%) of all energy produced in the United States. Globally, these percentages are estimated to be even greater (Architecture2030, 2011). Furthermore, the (CI) is responsible for generating most of the CO2 emission worldwide. The increasing concerns towards saving the environment, minimizing waste and using natural 918

resources efficiently called for the (CI) to be more sustainable. Great improvements have been observed in manufacturing, especially lean automobile industry which uses about 50% of manufacturing space, human effort in factories, product development time and investments in tools (Koskela, 2004). These improvements were the result of the development and implementation of a new production philosophy called “Lean Production”. This philosophy aims to avoid waste of time, money, equipment, effort and improving value through employing and combining existing approaches such as Just in Time (JIT), Total Quality Management (TQM), time-based competition and concurrent engineering (Melles and Wamelink, 1993). Adopting the “Lean Production” philosophy is expected to bring a revolutionary change to the way of work in every industry. In construction, lean production has been adopted relatively quickly by contracting companies which are keen to reduce waste in their construction projects. Even if only a small fraction of the gains observed in manufacturing were realised in construction, the incentive to apply these concepts would be tremendous (Emmitt et al., 2004). Hence, this paper aims to investigate the role of (LPs) as an innovative approach for achieving sustainability in the (ECI).

Research Methodology In order to achieve the aim of this research, a research methodology, consisting of literature review, case studies and survey questionnaire, is developed to accomplish five objectives. 1. Building a comprehensive background of the research topic by investigating the concepts of sustainability and (LPs), highlighting their relationship as well as discussing the ability of (LPs) to achieve sustainability objectives. This objective was achieved through conducting an in-depth literature review depending on textbooks, academic journals and

o rga n i za t i o n , te ch n ol o g y a n d ma na ge m e n t i n co nst r u c t i o n

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an international journal

professional magazines, conference and seminar proceedings, dissertations and theses, organisations and government publications as well as Internet and related websites. 2. Presenting and analysing four case studies to explore how (LPs) were applied to deliver sustainable projects. These cases were extracted from literature review and covered different project types in different countries including: residential complex in Brazil (Mota at al., 2005), industrial house builder in Sweden (Jansson et al., 2009), health care facility in Canada (Breen, 2011) and precast concrete production in Singapore (Wu and Low, 2010). Although there are many case studies about (LPs), the studied cases were selected as they are focused on applying (LPs) to achieve sustainability objectives. They were selected from different geographic areas, with diverse scope, nature, size and construction phases which helped accomplishing the study objectives and its argument. These case studies were analysed qualitatively through focusing on the application of (LPs) towards achieving the objectives of value, value stream, flow, pull and perfection. 3. Presenting and analysing results of a survey questionnaire conducted with a sample of (ECFs) to investigate their perception and application of (LPs) to achieve sustainability in construction projects. The survey questionnaire consisted of two sections. The first one aimed to collect general information about the surveyed organisations to form a profile of these firms, where the second section focused on investigating how (ECFs) perceive and apply (LPs) in order to deliver sustainable projects. The second section consisted of close ended (rating questions of 1 to 5 and multiple choice ones) and open ended questions. After the questionnaire was developed, it was essential to

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test its effectiveness and identify its problems. A preliminary test was conducted with colleagues who agreed to take the questionnaire and answer the questions as if they were received from someone unknown and go through the questionnaire again to point out any problem they noted with questions. After going over the responses of the preliminary test and making changes, the questionnaire was ready for formal testing (Baker, 1994; Czaja and Blair, 1996). Towards increasing the reliability and validity of the survey questionnaire, content validity was used through ensuring that the designed questionnaire was fully represent the underlying concepts of the subject being studied (Baker, 1994). In addition, a number of specialists were consulted to assess the extent to which the questions relate to the subject being investigated (Nachmias and Nachmias, 1996). Moreover, the same criteria used to analyse the case studies were also adopted when developing the survey questionnaire to help creating a correlation between the case studies and the survey questionnaire and their data analysis. 4. Developing a conceptual framework to promote the adoption and application of (LPs) as a powerful approach for achieving sustainability in the (ECI). 5. Outlining research conclusions and recommendations useful to governmental authorities and construction professionals towards achieving sustainability through (LPs).

Sustainability Background and Definition Sustainability, in a broad sense, is the capacity to endure. All the needs of current and future generations for survival and well being depend largely on the natural environment, either in a direct or an indirect way. Sustainability aims to create and maintain the environmental, social and economic conditions that allow humans to exist with a. a. e. othman

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nature in "productive harmony" in the present and the future (USEPA, 2009). Sustainability has become a wide-ranging term that can be applied to almost every facet of life on Earth, ranging from a local to a global scale and over various time periods. The existence of more than 70 different definitions for sustainability (Holmberg and Sandbrook, 1992) highlighted its importance and illustrated the efforts made by different academic and practical disciplines to define and understand its implications to their fields. However, all definitions agree that it is of prime importance to consider the future of the planet and develop innovative ways to protect and enhance the Earth while satisfying various stakeholders’ needs (Boyko et al., 2006). Scientific evidence showed that humanity is living unsustainably. This is obvious in the form of using nonrenewable resources, land dereliction, waste generation, water contamination, energy consumption, to name a few (Othman, 2010). Returning human use of natural resources to within sustainable limits will require a major collective effort. Since the 1980s, sustainability has implied the integration of environmental, social and economic spheres to meet the needs of the present without compromising the ability of future generations to meet their own needs (World Commission on Environment and Development, 1987). Sustainability Aspects Sustainability has three main aspects: Environmental, Social and Economic. The interaction between these aspects generated three new aspects, namely: Social-Environmental, EnvironmentalEconomic and Economic-Social (see figure 1) (Rodriguez, et al., 2002). � The environmental aspect of sustainability focuses on using natural resources efficiently; reducing waste, pollution, effluent generation and emissions to the environment. In addition, it aims to reduce the negative impact on human health,

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encourage the use of renewable raw materials as well as eliminate toxic substances. � A social sustainable society is one that is fair and accomplishes social justice when it comes to distributing its resources within itself. It is a society that would not discriminate in the rights of its individuals based on their ethnicity, sex, religion, age or social background (BenzuJK, 2011). These rights, which lead to a quality standard of living, include religious rights, right to housing, right to social security, right to work, freedom of speech, right to travel and right to own property. � A society with a high population under the poverty line cannot achieve sustainability as this is accompanied by high unemployment rate, lack of education and low quality health care systems (Karlsson, 2009). An economically self sustaining society is one that is able to use the available resources efficiently to provide its individuals with their needs without reaching out for help from neighbouring societies or countries. Towards developing an economically sustainable society, public and private sector has to play a role towards investing in R&D, offering employment opportunities, increasing productivity, escalating market share, adding value, creating new markets, reducing cost through improving efficiency and reducing energy as well as raw materials consumption. 6. The interaction between social and environmental aspects generated a new aspect which revolves around the right of all individuals to have a fair share of the natural resources of the environment at national and international levels. This ensures that these environmental resources are not exploited by a portion of the society leaving the rest of the society with needs that cannot be met by the remaining resources.

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Social - Environmental Environmental Justice Natural Resources Stewardship Locally & Globally (air, water, land, waste)

Environmental - Economic Energy Efficiency Subsidies / Incentives for use of Natural Resources

Environmental

Natural Resource Use Environmental Management Pollution Prevention (air, water, land, waste)

Social

Sustainability Economic

Standard of Living Education Community Equal Opportunity

Profit Cost Savings Economic Growth Research & Development

Economic - Social Business Ethics Fair Trade Worker's Rights

Figure 1. Aspects of Sustainability (Rodriguez, et al., 2002)

7. The economic–social aspect is the result of the interaction between economic and social aspects of sustainability. This aspect focuses on delivering economic sustainability without compromising society needs. This could be achieved through promoting business ethics, ensuring fair trade and preserving workers’ rights. 8. The interaction between environmental and economic aspects of sustainability generated a new aspect which focuses on achieving environmental objectives of sustainability in an economic way. This requires the reduction of unnecessary costs and efficient use of energy and natural resources. In addition, it offers subsidies and incentives for encouraging research centres and construction organisations to develop creative solutions to achieve economical sustainable environment.

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Lean Principles By referring to Oxford dictionary (2010), “Lean” means thin, lack in richness and quantity, economical, sharp and low content. The main idea beyond the lean concept is to maximize customer’s delivered value while minimizing waste. The lean theory can be summed up into five principles (Womack et al., 2003; Brookfield, 2004; Björnfot, 2006; Jansson, et al., 2009).

b) The Value stream principle maps the activities that, when done correctly and in the right order, will produce the product or service that achieve the customer’s value. Activities can be classified as (1) non-value adding activities which should be eliminated; (2) supporting the value-adding activities that should be reduced as far as possible; and (3) value-adding activities which should be continuously improved.

a) The Value principle focuses on identifying customer values and understating his/her requirements and constraints. In addition, it aims to define the internal and external factors that may affect the customer decision and find alternative solutions and most appropriate way to fulfil customer requirements at the most-cost effective manner.

c) The Flow principle aims to ensure that flow of work is steady and without interruption from one value adding or supporting activity to the next. Flow of work speeds the development process and hence, every effort should be made to eliminate obstacles that prevent such flow.

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d) The Pull principle establishes to produce only, products that have been

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Value Stream

X

X

Removing or reducing the influence of waste as it is observed.

X

X

Identifying the impact of internal and external factors that affect the customer decision and looking for alternative solutions that adapt to changes without losing much time, money or effort.

X

X

X

Maximizing the utility/outcome and benefit of the project.

X

X

X

Deciding the most appropriate way to deliver the customer’s requirements.

X

X

X

Defining all activities and recourses required for production.

X

X

X

Optimising work content through work standardization, repetition and preassembly and pre-fabrication.

X

Social- Environmental

X

Economic-Social

Identifying the project customer and understanding his/ her values, requirements and constraints.

Contributions of (LPs) Towards Achieving Sustainability in the (CI)

EnvironmentalEconomic

Social

Value

Economic

Lean Principles

Environomenatl

Sustainability Aspects

X

X

X

X

X

X

X

Defining and locating key component suppliers.

Flow

Organising and structuring job site materials, equipment, tools, and resources for efficient project execution.

X

X

X

X

X

X

Adopting the concept of work sequencing, crew balancing and work in progress reduction.

X

X

X

X

X

X

Reducing process cycle time through increasing work flow and task organization.

X

X

Identifying key performance indicators and measuring performance

X

X

Posting relevant information concerning schedule, cost, safety, and productivity about the job in a location that is convenient for all managers and crafts.

X

X

X

X

Incorporating all aspects of just-in-time delivery and minimising materials’ movement and relocation.

X

X

X

X

X

X

Keeping the production system flexible and adaptable to customer requirements and future changes. Pull

X

X

Exercising a conscious effort at shortening lead and cycle times. Optimising work content through managing the impact of design on the ability to achieve lean performance.

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X

X

X

X

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Perfection

Involving project participants through empowering them towards delivering best value to the customer, reducing waste and continuous improvement for organisational and project performance.

X

X

X

X

X

X

Training and educating project personnel to execute the designated role of delivering customer requirements.

X

X

X

X

X

X

Assimilating, retaining and transferring of knowledge throughout the organisation to enhance continuous process improvement.

X

X

X

X

X

X

Taking corrective actions to respond to defects and retaining those solutions for use in the future

X

X

X

X

X

X

Obligating all levels of management and supervision to the principles and practices of lean execution and continuous improvement.

X

X

X

X

X

X

Adopting the 5s’s (Separate/Scrap, Straighten, Scrub, Sustain, and Systematize) to improve delivering lean projects

X

X

X

X

X

X

Documenting and understanding all critical work processes performed by the project team.

X

X

X

X

X

X

Table 1. Relationship and Role of (LPs) towards Achieving Sustainability in the (CI)

ordered. In non-lean organisations, work is pushed (i.e. the system produces outputs that are not required). Most lean services react to customer demand, adapt to his/her changes and so pull the work through the system. e) The Perfection principle seeks to deliver exactly what the customer needs, when needed and at the most cost-effective manner. In a perfect process, every step is valuable-adding, capable (produces a good result every time), available (produces the desired output, not just the desired quality, every time), adequate (does not cause delay), flexible, and linked by continuous flow. If one of these factors fails some waste is produced. Perfection is a journey of continuous improvement and Lean organisations have to strive for perfection and develop strategies and procedures to set up quality controls and achieve perfection. 922

The Relationship and Potentials of (LPs) towards Achieving Sustainability in Construction Current generations have the right to use the natural resources to achieve their goals and meet their needs. But using these resources inefficiently compromises the ability of future generations to meet their own needs. Therefore, there should be a trade-off between high comfort modern buildings versus resource consumption and environment degradation. The (CI) needs to be more sustainable and learn from other industries, such as manufacturing, that succeeded in maximising customer’s values and minimising waste of resources, time and effort (Williams, 2000; Huovila and Koskela, 1998). This will encourage the (CI) to adopt (LPs) as a powerful approach to increase its efficiency and effectiveness. Analysis of the objectives of (LPs) and aspects of sustainability enabled

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the authors, to generate a matrix to explain the relationship between both disciplines and the role of (LPs) towards achieving sustainability in construction (see Table 1). For example, through applying the Value principle, proper identification of the project customer and understanding of his/her requirements helps the project team to deliver a product that satisfies the customer needs and reduces waste of materials, time or effort. In addition, this helps adapting to the internal factors (i.e. changing customer needs) and external factors (i.e. global economic recession) that affect the customer decision. Furthermore, the Value principle helps select the most appropriate way to deliver the customer requirements in a lean manner. Another example that explains of the role of (LPs) in achieving sustainability in construction is the Perfection principle. This principle focuses on empowering project teams, training them to execute the designated

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Value

Value Stream

Flow Analysing work flow activities according to the construction rate that was defined in the traditional model.

Recognising that Time is the most important value to the customer.

Adopting the Line of Balance (LOB) as a tool to assure and maintain continues work flow.

Completing the project one month earlier which allowed the investor to recover his investment sooner than expected.

Motivating workers to maintain and increase their productivity rates by providing incentives, a win-win situation.

Ensuring and maintaining workflow through moving workers who completed a certain task in a unit to do the same task in the following unit until the last house is finished. Ascertaining that all materials needed to complete a certain task are available at the work stations before the workers shifts’ begin.

Pull

Reducing the waste of environmental resources as the firm purchased only the amount of materials needed with minimal leftover. Developing a procurement system to alert the purchaser when materials are needed to ensure that workflow is not disturbed because of deficiency of materials.

Perfection

Improving organisational performance and finding solutions to problems through encouraging workers to contribute their opinions towards meeting their needs and increasing work productivity as well as reporting any errors and obstacles may arise.

Table 2. Achieving Sustainability through (LPs) Application in the Residential Complex Project

role to deliver the customer’s product. In addition, it helps improving performance through adopting the appropriate delivery techniques, assimilating, retaining and sharing knowledge, corrective actions and learned lessons. Furthermore, Perfection principle obligates all organisational levels to execute (LPs) and practices and strive for continuous improvement (Björnfot, 2006; Brookfield, 2004).

Barriers to Achieving Sustainability in Existing Construction Practice

adopted in construction projects and the involvement of multitude of various project participants with diverse objectives, skills and interests tended to separate design from construction. This separation obstructs contractors from providing designers with constructive feedback and suggestions for design improvement, which ultimately hampers the development of sustainable construction (Othman, 2011; Forbes and Ahmed, 2011). Other barriers that hinder the inplmentation of sustainability in construction include (Tomkiewicz, 2011).

The barriers to achieving sustainability in the currecnt construction practice are generally based on the nature of the (CI) and the culture of construction professionals and project participants. Basically, the existing (CI) is known for its chronic problems of fragmentation, low productivity, time and cost over-runs, poor safety, inferior working conditions and insufficient quality. In addition, the traditional procurement approaches commonly

� Market perception where no consumer demand for such a product. The (CI) is ultimately a business, and like any other, it aims to satisfy user demand. If there is no perceived demand, builders are not motivated to supply the product, unless perhaps, out of a desire for environmental philanthropy. � Information gaps, where there is lack of clarity of the direction or

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meaning of sustainability practices among academics and construction professionals. � Lack of infrastructure, conflicts with permits, code compliance, appraisal and financing impede alternative sustainable construction methods. � Lack of commitment of architects and contractors. Their aim is to reduce initial costs and make a fast profit. With limited architectural involvement, the integration of whole design practices and teaming required for a full implementation of sustainability becomes improbable. Additionally, it becomes difficult to develop a communal knowledge base, which extends beyond individual properties.

Case Studies benefitted from Lean Principles Application in Construction This section presents a number of international best practice projects to explain the role of (LPs) towards delivering sustainable construction projects.

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Value

Value Stream

Establishing organisational strategies to focus on meeting / exceeding customer expectations. Creating value for the customers by handling up to 6 projects in parallel with flexibility in the design process (see Figure 2).

Focusing on the main processes of the project and reducing effort invested in standardising sub-tasks. Optimising time and human resources in activities that bring an economic value to the firm, and accordingly to the society.

Adding value for the design team through conducting weekly meetings and sharing of information with different project participants.

Flow

Pull

Expediting flow of information and drawings in the design process. Reducing the number of different software used to save time and reduce the amount of errors and damaged files when converting from one format to the other. Standardising processes to eliminate unnecessary workloads and reduce the amount of re-work and materials as well as energy consumed during producing faulty products due to errors.

Eliminating project waste through applying the concept of constructability at early stages of the project life cycle.

Perfection

Facilitating the production process and making better use of the short time allowed for construction (4 weeks) through streamlining the construction process and information flow.

Using visual planning, checklists, templates and quality routines for following up the development of projects.

Using prefabrication methods to reduce the percentage of error on site that could result in economic waste or a misuse of environmental resources.

Table 3. Achieving Sustainability through (LPs) Application in the Industrial House Builders

Project 1

Project 2

Project 3

Sales

Arch Dwg

Sales

Building Design

Building Design

Arch Dwg

Sales

Info. Docum

Arch Dwg

Volume Cons. Info. Docum

Building Design

Activity

Volume Cons.

Info. Docum

Activity

Activity

Volume Cons.

Activity

Activity

Activity

Preparing for prod.

Preparing Activity for prod.

Activity

Activity

Preparing for prod.

Timeline

Figure 2. Design process illustrated in project and process based work (Jansson et al., 2009) Residential Complex, Fortaleza, Brazil This is a residential complex project constructed in the urban area of Fortaleza, Brazil. It consisted of 18 houses financed by a private investor and was constructed and managed by a small-sized construction firm. Because 924

of the gained benefits, the construction firm decided to go through the lean path after completed this project. The workers finished house (09) using the traditional construction techniques and then applied (LPs) to complete the rest of houses (Mota at al., 2005). Table (2) summarises the contributions of (LPs)

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towards achieving sustainability objectives in the residential complex project. Results of applying (LPs) helped achieving the objectives of sustainability aspects through increasing work productivity rate by 15.7% and reducing project duration by 12.5%. In addition, they assisted accomplishing

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Value Identifying the rate of usage of each department by patients, medical and administrative staff.

Value Stream

Flow

Pull

Perfection

Identifying the activities and transportations within the centre that cause the most delays to the patient and waste of time and materials.

Minimising the congestion in case sensitive areas such as emergency department) through identifying the most favourable patterns for the different users of the facility to follow.

Attracting the customer flow to certain areas by creating land marks within these areas to reduced congestion and enable more efficient process execution to take place.

Ensuring design effectiveness, not only through creating scaled models to the different rooms in use in each department, but also by developing a 1:1 scaled layout of the final design to test important features such as line of sight, speed of flow and efficiency of delivering services to the designated patient (see figures 3 and 4).

Deciding on the equipment that are urgently or most needed.

Shortening the distance between the patient and the designated area and service provider. Optimising the flow of information, equipment, supply, processes and food.

Gathering customers’ feedback to enhance the final layout design even more.

Table 4. Achieving Sustainability through (LPs) Application in the Health Care Facility

the economic-social objectives of sustainability through using an incentive system to motivate workers achieve the goals determined by the firm and respond to the challenges defined by the project schedule. If this trend of efficiency continues in similar firms, the society is the one to benefit from the extra time, more available economic and environmental resources because these extra resources will be relocated to increase the individual's share. Industrial House Builders, Sweden Industrialized housing represents a growing market segment in the construction market in Sweden with an approximate market share of 15 % (Björnfot, 2006). This project is of a Swedish timber housing firm specialized in student lodgings, hotels and senior dwellings. The buildings usually go as high as four stories. Their clients are mainly accommodating building societies, realestate clients and student associations. The customization and standardization degree is common within these projects. The firm employs 135 employees who are a. a. e. othman

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located at a single production site and they have an average annual turnover of 42 Million Euros (Jansson et al., 2009). Table (3) concludes the contributions of (LPs) towards achieving sustainability objectives in this project. Through applying (LPs), the project succeeded in achieving a number of sustainability objectives. Firstly, handling parallel projects with flexibility during the design process as well as sharing information helped minimising waste and adding value to the customer and the design team. Secondly, by maintaining its processes and not investing in standardising sub-tasks, the firm saved its time and human resources efforts. Finally, using the pull strategy as the design duration is longer than the production time helped delivering needed products without generating waste or misuse of environmental resources. Health Care Facility, British Columbia, Canada. Provincial Health Service Authority (PHSA) plans, organises and evaluates specialty and general health

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care services in the province of British Columbia (BC), Canada. PHSA's projects include BC Women’s Hospital and Health Centre. The authority has been implementing lean in its projects for almost 4 years. Recently, the current children’s inpatient building, and BC Women’s Neonatal Intensive Care Unit (NICU) and the Birthing Suite in the children’s and women’s health centre needed to be replaced. The replacement process of the children's inpatient centre process was planned to take place on three phases starting by demolishing and relocating the centre, building the new acute care centre and finally renovating the old centre (Breen, 2011). Table (4) concludes the contributions of (LPs) towards achieving sustainability objectives in this project. This project relied on modelling a new design layout and testing its efficiency first hand by allowing the employees to simulate the flow of the building occupants. Being a health care centre, the flow of the building occupants through the centre is the main challenge faced while designing the

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Figure 3. Mock ups scale 1:1 to the Inpatient and Oncology units (Breen, 2011)

Value

Figure 4. Mock ups scale 1:1 to the Inpatient Elevator (Breen, 2011)

Value Stream

Flow

Reducing carbon production during precast concrete production.

Eliminating waste of time through reorganising material storage for production.

Placing site layout plan on the notice board for information.

Improving assessment of environmental values.

Considering alternative transportation methods to reduce lead time and cost.

Improving the value chain of precast concrete production. Proper identification of required material for production to avoid reorder and re-delivery of correct materials.

Pull Eliminating the over provision for material storage.

Maintaining long-term contact to achieve loyalty between suppliers and precasters.

Perfection Reducing unplanned changes in the specification of precast concrete production. Making better use of research in green building materials. Training incompetent employees and having proper written production manual.

Maintaining clear identification of marks and delivery notes in the contract period.

Enhancing employees care towards avoiding waste of finished products and wrong delivery.

Table 5. Achieving Sustainability through (LPs) Application in the Precast Concrete Production

circulation. Therefore, value stream mapping and flow presented guidelines to be followed to overcome theses circulation challenges (Breen, 2011). Precast Concrete Production, Singapore. Precast concrete products are widely adopted in the Singapore construction industry due to the rising demand from public housing projects. One of the solutions to reduce construction duration and improve efficiency would be to 926

use precast concrete products which are able to provide a cost-effective way of carrying out “system building” types of construction projects. Table (5) summarises the results of applying (LPs) towards improving the sustainability of precast concrete production practices (Wu and Low, 2010). Through applying (LPs), it was possible to reduce costs and eliminate waste through improving the efficiency of the process, improve quality and focus on adding value activities for customer

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satisfaction and ensures health and safety standards for workers through providing information on the information board as well as reduce carbon emission. In addition, (LPs) application helped improving training program for supporting sustainable operations and efficient use of raw materials and resources.

Field Study This section presents the results of a field study conducted, by the authors,

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through a survey questionnaire to investigate the perception and application of (LPs) as an approach for achieving sustainability in the (ECI). The questionnaire sample was selected from the list of 14000 contractors registered with the Egyptian Federation for Construction and Building Contractors (EFCBC, 2012). To get a representative and reasonable sample size that supports the research findings, the following equations were used. Equation (1) is applied to compute the initial sample size. Since the population is finite (less than 50,000), Equation (2) is used to compute the new sample size (Johnson and Bhattacharyya, 2009; Freedman et al., 2007). SS = Z2 * (p) * (1-p) / c2 Equation (1)

4.5

4.54

4 3.5

3.1

3

Where: SS = Sample Size Z = Z-values for confidence levels are (1.645 for 90% confidence level, 1.96 for 95% confidence level and 2.576 for 99% confidence level) p = percentage picking a choice, expressed as decimal (0.5 used for sample size needed) c = confidence interval, expressed as decimal (e.g., .08 = ±8) Pop = Population In our case: SS = (1.96)2 * (0.5) * (1 - 0.5) / (0.08)2 = 150.063 New SS = 150.063 / (1+ (150.063 - 1) / 14000) = 148.48 ≈ 148 The same result was confirmed by the sample calculator (The Survey System, 2012), through using a confidence level of (95%) and confidence interval of (8) when combined with a population of (14000) contracting

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3.13 2.49

2.5

2.26

2 1.5 1 0.5 0

Value

Value Stream

Flow

Pull

Perfection

Figure 5. Average Areas of (LPs) Applications in Construction

39

40

New SS = SS / (1+ (SS-1) / Pop Equation (2)

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35 30

30 25 20

20 15 10

10

5 0

2 Briefing

Design

Tendering

Construction

After Completion

Figure 6. Responses of the Phases of Applying (LPs) troughout the Project Life

companies yielded a suitable sample size of (148) participants. This approach is adopted by many researchers to avoid using manual and complicated sample size formulas. Sample size calculator is an online simple and accurate tool designed to analyse sample size through giving researchers different options to select from (Bridges, 2013). These firms were contacted and the questionnaire was delivered to them either by hand, mail or e-mail. Out of 148 questionnaires were sent, only 67 were completed and returned, providing a response rate of 45.27%.

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According to Babbie (1992) as a rule of thumb 50% is adequate while, McNeil and Chapman (2005); Saunders et al., (2003); Gillham (2000); Tashakkori and Teddlie (1998); Fellows and Liu (1997) state that 30-40 per cent is acceptable because of the fact that few people respond to questionnaires. Data Analysis of the Survey Questionnaire Perception and Application of (LPs) in Construction Projects 39 out of 67 respondents to the questionnaire, which represent

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(58.2%), stated that they perceive the concept and apply it in their projects (by adding value to customers while eliminating waste) without knowing that this practice is called Lean. On the other hand, the remaining companies mentioned that they have not adopted (LPs) approach in their projects. Area of Focus when Applying (LPs) in Construction Projects Figure (5) shows the responses of the surveyed firms to rate the areas of their focus when applying (LPs) in construction projects, namely: Value, Value Stream, Flow, Pull and Perfection. These areas were used to analyse case studies. Results showed that the concept of “Value” received (4.54) out of (5) which ensures that proper understanding of clients / customers value system is paramount towards delivering their requirements in a lean manner. This is followed by “Perfection” and “Flow” with an average of (3.13) and (3.1) out of (5) respectively, which indicates that continuous improvement and built-inquality as well as flow of information and materials are key elements towards using (LPs) to achieve sustainability in construction projects. The Internal Governance towards (LPs) Adoption and Application in (ECFs) Towards investigating the internal governance of the surveyed firms towards adopting and applying (LPs), respondents were asked to select between “internal governance” as the firm’s vision for the future, “mission statement”, “lean objectives” or “others”. Responses are: � 20 out of 39 respondents, which represent (51.28%), stated that “mission statement” was the most popular form of governance that their firms used. “Mission statement” of these firms focuses on achieving customer satisfaction through delivering products that best meet or exceed his/her expectations at the most cost effective manner. 928

� 10 out of 39 respondents, which represent (25.64%), mentioned that “lean objectives” were ranked second as the firm governance. Firms believe that “lean objectives” are the right thing that has to be done towards saving the environment, prospering economy and serving the society. � 9 companies out of 39, which represent (23.07%), stated that the “vision of their companies” in the future is the internal governance for (LPs) adoption and application. Companies consider (LPs) as a competitive advantage tool that will increase their market share in the future and assist the firm to remain competitive in the market. Phases of (LPs) Application in Construction Projects Figure (6) summarises the responses of the surveyed firms to investigate the different phases of applying (LPs) in construction projects, namely: Briefing, Design, Tendering, Construction and After Practical Completion phase.

Results showed that all surveyed firms adopted (LPs) towards achieving sustainability during the design phase as decisions taken during this phase have important impact on the constructed facility throughout its life cycle. In addition, 30 out of 39 firms, which represent (76.92%), adopted (LPs) during the construction phase as many of lean activities are related to site construction such as material provision and storage as well as site layout and workers movement and the application of lean principles in this phase has positive impacts. The Potentials and Constraints of Adopting and Applying (LPs) in (ECI) Responses of the questionnaire with regard to the reasons that encouraged (ECFs) to adopt and apply (LPs) in construction are as follows: � 20 out of 39 respondents, which represent (%51.28), stated that (LPs) are used because they are good marketing tool; improve productivity,

Policy

Delivery

LPAAF Training

Champion

Guidelines

Figure 7. Components of the Lean Principles Adoption and Application Framework

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increase customer satisfaction and reduce waste of time and effort. � 19 respondents highlighted that (LPs) helped them minimise project cost, add more value to the customer, increase firms’ performance, improve flow of information and facilitate communication. The 28 firms that did not adopt (LPs) have identified the reasons that hindered the adoption and application of (LPs) as: � It is not mandatory requirements either by customers, construction industry or governmental authorities. � Lack of knowledge and perception of the lean concept. No training programmes are offered to educate construction professionals about the new concept either at undergraduate, postgraduate or industry levels. Respondents mentioned that (LPs) are not dealt with as a strategic objective by firm’s management. � Time and money constraints. Respondents believe that new concepts such as (LPs) are expensive and time consuming. Firms prefer to use tested and successfully proofed methods rather than applying new concepts. � There is no formal framework to integrate (LPs) in (ECFs).

A Conceptual Framework for Promoting the Adoption and Application of (LPs) in Construction Firms Framework Rationale and Development Results of literature review, case studies and field study revealed that (LPs) are powerful approach to achieve sustainability in construction projects. On the other hand, it is of prime importance to have a formal framework to facilitate the adoption and application of (LPs) in construction firms and establish the strategies that support its success. In order to ensure the successful a. a. e. othman

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implementation of (LPs), construction firms should be Lean oriented. A lean firm understands customer value and focuses its key processes to continuously increase it. The ultimate goal is to provide perfect value to the customer through a perfect value creation process that has minimum or zero waste. This necessitates that the whole firm should be involved in the lean process development. The Lean Principles Adoption and Application Framework (LPAAF) outlines and relates the components which support (LPs) application in construction firms and serves as a guide that can be modified to meet organisational needs. Components of the Framework The proposed framework consists of five elements, namely: Policy, Champion, Guidelines, Training and Deliver (see Figure 7). Policy The Firm’s policy should establish the need to adopt and apply (LPs) and justify what benefits this approach expects to generate. For instance, these benefits could be delivering sustainable projects, maintain firm’s competitiveness or improve communication and information flow. The policy has to provide clear guidance on when (LPs) have to be integrated throughout the project life cycle and what are the resources needed. The policy should state, in broad terms, to which areas of the business (LPs) are to be applied and provide guidance on the scale of that application. It should also state whether the firm intends to generate its own internal delivery capability or rely on buying in the expertise when needed or a mixture of the two. It should set out a timescale within which they expect to embed the practice of (LPs) into the firm’s culture. Champion Once the firm’s policy has been stated, it is essential to appoint an individual to implement this policy. The appointed

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individual will be designated as the Head of Lean Principles Programme (HLPP). Senior management has to form a small steering group, which represents the various parts of the firm, to whom the (HLPP) will report and discuss progress. Members of the steering group should report to the firm’s board of directors. The (HLPP) has to possess a sound understanding of (LPs) and their application. In addition, s/ he should draw up a plan setting out how the policy will be implemented and corrective actions to be taken in case the procedures deviated from the developed plan. Guidelines The (HLPP) is responsible for setting out guidelines that describe the types of study that should be conducted at strategic, programme, project and operational levels. The guidelines should outline the process to follow, list suitable techniques to be used; provide guidance on who should be involved and the level of competence and experience of the leader who will lead the studies of implementing (LPs). The guidelines should provide also, the basis for delivering repeatable processes but not be so prescriptive as to stifle individual interpretation and innovation. Training Training provision is the first step towards achieving the plan of adopting and applying (LPs) in construction firms. It has to be shaped by the policy either by using internal or external expertise. If the firm plans to use only external expertise due to lack of internal resources for instance, the training programme will be focused on building up an awareness of (LPs) and their benefits at all levels of the firm. This is essential to gain support throughout the firm and to build up a collaborative culture. If it is intended to build up internal delivery expertise, it is essential to train up or employ internal study leaders with competent delivery skills levels. To ensure

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that the training programme is effective, it should be accredited by a competent organisation and lead to a professional qualification. Both the awareness and the practitioner training courses should align with the firm’s policy and its approach to doing business. Delivery The second step of the plan is the delivery of the services themselves within the designated projects using the appropriate techniques. The (HLPP) should gather feedback from all participants, in addition to the formal reports to build up an information base and learn from experience. The lessons learned have to be incorporated into the training programme and shared between employees to ensure that the quality of service is continuously improved. Strategies for Successful implementation of the Framework For the (LPAAF) to be successfully adopted and implemented in construction firms, certain strategies should be in place as follows: � Clear identification and visible senior management support for (LPs) adoption and application. � Explicit policies which are clearly communicated to all employees. � Creating a culture that supports and understands the concepts of maximising value and minimizing waste. � Fully embedded management processes which are consistently and rigorously applied and are clearly linked to the achievement of (LPs) objectives. � Effective implementation of plans and regular reviews to ensure that the benefits of (LPs) are realised and lessons are learned for future programmes. Framework Limitations and Potentials The effective application of the framework depends to a large extent on the 930

encouragement of the top management in construction firms to adopt (LPs) as an approach to achieve sustainability in construction. If the top management does not have the desire and tended not to use the framework, then its adoption will be limited. In addition, the application of the framework is a long-term strategy to improve the traditional culture and methods of doing work in construction, and hence it could be resisted by some sectors of the (CI). For this reason, it is essential that the benefits of the framework be clearly presented to top management of construction firms in order to get them convinced with the role, which the framework could play in improving their performance and achieving sustainability in their projects. This will increase the opportunities for adopting the framework. Although the developed framework is a conceptual one and not validated due to the limited resources of the authors and time needed, it provides construction firms with detailed components that explain how to adopt and apply (LPs) in their projects.

Conclusions and Recommendations After reviewing the fundamentals of (LPs), sustainability and investigating a number of case studies that benefitted from (LPs) towards delivering sustainable products, and keeping in mind the results of the field study, the research come to the following conclusions and recommendations: � The (CI) plays a significant role towards social and economic development at national and international levels. However, it has negative impact on the environment being a source of waste, energy consumption, land dereliction and pollution. This called for the (CI) to be more sustainable through using natural resources in an efficient way to enable current generations to meet

o rga n i za t i o n , te ch n ol o g y a n d ma na ge m e n t i n co nst r u c t i o n

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an international journal

their needs without compromising future generations from achieving their own needs. � (LPs) have proven to be a powerful tool to minimize waste and adding better value to customers in the manufacturing industry. The application of (LPs) in construction helps defining customer value, eliminating waste, improving flow of work and information and increasing organisational perfection. � Results of the field study showed that (LPs) are generally perceived and applied in a number of (ECFs) without realising that these practices are called lean. These concepts are used mainly in the design phase and construction phases. On the other hand, other firms stated that (LPs) were not adopted due to a number of reasons such as it is not mandatory requirement, lack of knowledge, time and cost constraints as well as the absence of formal frameworks to integrate (LPs) in (ECFs). This led to the following recommendations: � Recommendations to Governmental authorities in Egypt • Governmental authorities responsible for construction and urban development are advised to promote the use (LPs) as a strategic approach towards achieving sustainability in construction. • Issuing and enforcing legislations to facilitate the adoption of (LPs) in design and construction firms as well as developing incentive programmes to attract and acknowledge the firms that adopt (LPs) and succeeded in delivering sustainable projects. • Integrating (LPs) in architectural and construction education at undergraduate and graduate studies to generate graduates who understand the concept and its benefits and hence, apply it in their projects. • More seminars, conferences, training programmes that are concerned

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with (LPs) and sustainability should be organised on regular bases in an effort to educate the industry players and share research findings with construction professionals. � Recommendations to Egyptian Construction Firms • (ECFs) are advised to integrate lean philosophy in their business development strategy. This requires establishing the need to adopt and apply (LPs) and justifying what benefits that this approach could generate. In addition, it necessitates senior management support and provides clear guidance on when (LPs) have to be integrated throughout the project life cycle and what are the resources needed. The policy should state, in broad terms, to which areas of the business (LPs) are to be applied and provide guidance on the scale of that application. • Offering training programmes to enhance the skills of employees and increase their capabilities towards perceiving and applying (LPs). (ECFs) have to decide whether to generate its own internal delivery capability or rely on buying in the expertise when needed or a mixture of the two. It should set out a timescale within which they expect to embed the practice of (LPs) into the firm’s culture. • Focus should be directed towards applying (LPs) during the briefing and after practical completion stages being got the lowest average amongst the different stages of the project life cycle. These are two essential milestones for delivering sustainable projects. At the briefing stage, important decisions are made which affect the performance of the project throughout its life cycle, where feedback gained from the after practical completion stage help improving design decisions taken in earlier stages. • Validating and applying the proposed framework will help a. a. e. othman

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construction firms adopt (LPs) to achieve sustainability in construction projects.

A Guide to Decisions and

Construction and Building Contractors.

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Lean Processes for Sustainable Project Delivery

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Anthony R. Lapinski1; Michael J. Horman2; and David R. Riley3 Abstract: Facility owners and project teams often struggle to engage “green” or “sustainable” requirements on building projects and can incur additional project costs as a result. Although “investments” in high performance building features can be paid back through operational savings, the project delivery methods currently adopted by most teams are laden with process waste. Lean production principles have been proven to reduce waste and improve process performance in highly complex development and production environments. Adopting these lean principles, this paper reports a study that identified the presence of value and waste in a sustainable building project. Through an empirical investigation of the Real Estate and Facilities Division of Toyota Motor Sales, Toyota’s capital facility delivery process was mapped to identify both the steps in project delivery critical for success 共value兲 and those that are waste. The investigation focused on the South Campus Facility, which received U.S. Green Building Council’s Leadership in Energy and Environmental Design Gold certification at a project cost equivalent to a conventional facility. Through post hoc process-based analysis, insight about what added value and waste in sustainable project delivery at Toyota was obtained. The results also identify further improvement opportunities to Toyota’s delivery process. For corporate facility owners and the Architecture Engineering Construction industry, the results unearth insights about how to successfully and economically deliver sustainable facilities. DOI: 10.1061/共ASCE兲0733-9364共2006兲132:10共1083兲 CE Database subject headings: Delivery; Sustainable development; Construction industry.

Introduction “Green” or sustainable buildings offer numerous benefits including energy efficiency, improved indoor environment quality, increased health and occupant productivity, and the minimization of resource usage during the construction and operation of the building. Consequently, these buildings achieve superior long-term performance making them attractive investments for facility owners and developers in both the public and commercial sectors. However, to achieve their performance benefits, additional requirements are often needed in the delivery processes for sustainable buildings. For example, sustainable building projects require intense interdisciplinary collaboration, highly complex design analysis, and careful material and system selection, particularly early in the project delivery process 共Riley et al. 2004兲. Additionally, locally manufactured, often untraditional, and higher priced materials can be required for construction; and if certification under the U.S. Green Building Council’s Leadership in Energy and Environmental Design 共LEED兲 is sought, extensive docu1 Formerly, Graduate Student, Dept. of Architectural Engineering, Penn State Univ., 203 Engineering Unit A, University Park, PA 16802. 2 Associate Professor of Architectural Engineering, Penn State Univ., 211 Engineering Unit A, University Park, PA 16802. E-mail: [email protected] 3 Associate Professor of Architectural Engineering, Penn State Univ., 220 Engineering Unit A, University Park, PA 16802. E-mail: [email protected] Note. Discussion open until March 1, 2007. Separate discussions must be submitted for individual papers. To extend the closing date by one month, a written request must be filed with the ASCE Managing Editor. The manuscript for this paper was submitted for review and possible publication on July 25, 2005; approved on March 20, 2006. This paper is part of the Journal of Construction Engineering and Management, Vol. 132, No. 10, October 1, 2006. ©ASCE, ISSN 0733-9364/2006/10-1083– 1091/$25.00.

mentation adds time and cost to the project 共Pulaski et al. 2003兲. To account for the additional requirements posed by sustainable buildings, an up-front or first cost premium is commonly associated with this building type. This up-front cost is used to purchase better quality building components like HVAC systems and superinsulated building envelopes. This “investment” can achieve significant operational savings that extend over the life of the building. However, the current project processes used to deliver sustainable buildings are often laden with wasteful rework, delays, changes, and overproduction 共Horman et al. 2004兲. Project delivery processes are the processes used to get owner needs to a constructed facility, and include programming, procurement, design, construction, and turnover. We suppose that part of the reason for high process waste is that owners and project teams have a limited understanding of which processes are the important ones for sustainable project delivery. Further, the intermediate deliverables, activities, and outcomes of current delivery processes are best suited for conventional building types and are often unresponsive to the needs of sustainable building projects 共Lapinski et al. 2005兲. For instance, traditional delivery processes make little explicit mention of important sustainable activities such as energy modeling. Critically, the increased first cost associated with sustainable buildings is a major barrier for owners to pursuing sustainable building objectives. A number of exemplary sustainable buildings, however, are emerging to suggest that the requirements of sustainable projects need not lead to increased project costs. Facility owners like Toyota Motor Sales have been able to deliver LEED Goldcertified facilities without a first cost premium 共Pristin 2003兲. This is a notable accomplishment compared to an industry average 5–10% cost premium often needed to deliver LEED certified buildings 共Smith 2003兲. Teams experienced in sustainable building development are revealing that process efficiencies are key to the low-cost delivery of sustainable buildings. This is a critical emerging development

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in our industry. As the Architecture Engineering Construction 共AEC兲 industry becomes more adept at the technologies for sustainable buildings, it must also understand and overcome the process issues of these buildings. This industry needs to identify which processes enable sustainable goals to be achieved most efficiently. Although our community has studied lean project delivery and sustainable building objectives for some time, there has been little scientifically supported research that combines these two domains together. Armed with the theory that process waste affects both sustainable outcomes and the business case for sustainability, this paper analyzes the delivery process of Toyota’s capital facilities program. Advances in manufacturing processes, especially those in lean production, demonstrate the power of harnessing production science to improve product quality 共increasing value兲 and at the same time dramatically speeding production and reducing costs. Using principles of lean production, the Toyota capital facilities process is systematically modeled and analyzed to capture and understand the key process attributes. This will provide an understandable breakdown of which processes add value and help to define what process improvements in sustainable building projects look like, thus helping the AEC industry to achieve lowcost sustainable buildings.

Objective The purpose of this paper is to evaluate, using the scientific approach, the life cycle of Toyota’s capital facility delivery process to empirically identify the critical activities and capabilities that led to Toyota’s South Campus project success. This will involve a post hoc process-based analysis to identify where value and waste were generated in Toyota’s delivery system.

Background Sustainable Project Delivery: Toyota and U.S. General Services Administration „GSA… Toyota Real Estate and Facilities 共RE&F兲 is responsible for the development, design, construction, operation, and maintenance of all Toyota Motor Sales in North America 共TMS兲 corporate facilities. TMS are responsible for all postmanufacturing operations at Toyota Motor Company. The design and construction of Toyota’s manufacturing facilities throughout the world are the responsibility of Toyota in Japan, not TMS. Thus, project types undertaken by RE&F include corporate offices, parts and vehicle distribution centers, logistical support facilities, training facilities, financial facilities, executive housing, and airport hangars. Their work involved 80–100 projects at a total yearly budget of $100 million. Vehicle distribution centers, parts distribution centers, and technical training facilities comprise the bulk of their work. Toyota’s first LEED certified building was the South Campus facility located in Torrance, Calif. 共see Fig. 1兲. This three-story office building of approximately 59,500 m2 共640,000 ft2兲 received Gold certification. Some of the noteworthy features of the facility include: • Reclaimed water used for irrigation, toilets, and absorption chillers, eliminating the use of almost all potable water; • Equipment in heating, ventilation, air conditioning, and refrigeration does not require ozone depleting chlorofluorocarbon

Fig. 1. Toyota Motor Sales’ South Campus facility received Gold LEED certification

共CFC兲-based refrigerants by use of a mechanical system including absorption chillers and boilers; • Energy performance exceeds California Title 24 State Energy Code by over 42% and American Society of Heating, Refrigerating and Air-Conditioning Engineers 共ASHRAE兲 standards by 60%. The roof holds the largest photovoltaic array in California providing 20% of the building’s total energy 关2,232,000 MJ 共620,000 kWh annually兲兴; • Over 50% 共by value兲 of materials including all system furniture have incorporated recycled content material to reduce the impacts from extracting new materials; and, • 97% of construction waste was recycled to avoid landfills and recyclable materials directed back to the manufacturing process. This included using tilt-up casting beds as stone steppers in the garden areas. At $87 million, this was an unusually large project for Toyota. However, a project cost of $6 / m2 共$63/ ft2兲 lies in the range of $5 to $7 / m2 共$54 to $76/ ft2兲 for most of southern California office parks indicating that Toyota was able to obtain an environmental building of very high standard at little or no additional cost over a conventional building 共Pristin 2003兲. A study by the GSA 共2004兲 of the cost of pursuing LEED on their facilities showed that a modest budget allocation of 2.5% was sufficient for them to achieve Silver certification. The report concluded that this cost was well within the regular estimating “noise” of their projects, i.e., the typical range of cost variations they experience due to estimating and change orders. Clearly, owners such as Toyota and GSA have effective teams and processes for delivering their sustainable facilities that should be closely studied so our industry can learn how to efficiently deliver their green facilities. Lean Production: Focus on Process Process-based theories and modeling strategies can help to understand the delivery attributes of sustainable buildings. The Toyota Production System 共TPS兲 and its lean principles provide insight about the way a process is recognized, documented, and assessed for improvement. The TPS utilizes a process-oriented approach to maximize value generation for the customer by stripping away process waste and enhancing production flow. Identifying instances of value and waste first begins by defining the customer

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base. The customer base of the TPS is the vehicle owner. Value is generated by meeting the needs of owners in terms of price, color, options, availability, etc. 共Bremner 2003兲. Conversely, waste is any activity or process that adds no value to the customer. The lean analysis of production flow requires documentation or mapping of the process 共Liker 2004兲. This process map emphasizes a total process perspective and provides prerequisite understanding for analyzing processes for value and waste. At Toyota, impressive performance has resulted from the process maps, corresponding analyses, and adopted value-enhancing and waste-eliminating improvements. Manufacturing lead times have fallen by 48%, productivity has increased by 53%, quality has improved by 65%, and product development is completed with 45% fewer engineering hours at a pace 24% faster than any of Toyota’s U.S. counterparts 共Womack et al. 1990兲. Applying the lean principles of the TPS to Toyota’s capital facility delivery process offers important procedural guidance to capture and understand the enablers of their success as well as opportunities to improve their process further. Inspired by Koskela’s 共1992兲 important study of production theories in construction, this industry has embraced lean principles for nearly 15 years. Most research and implementation has focused on construction processes, especially addressing the waste-inducing effects of poor planning 共e.g., Ballard and Howell 1998兲. Some work has extended to the design process, and even lean project delivery 共Ballard and Zabelle 2000; Ballard 2000兲; although, the results have not yet matched those achieved by Toyota manufacturing. The lean construction community has performed a number of modeling and simulation studies of project and supply chain processes 共e.g., Tommelein and Li 1999; Tommelein and Weissenberger 1999; Arbula and Tommelein 2002兲, although these studies have been confined to partial segments of the delivery process and do not necessarily emphasize understanding where value is generated or lost. The synergistic and cost-saving link between process waste reduction in the TPS and reduced resource use in sustainable development has been made by others, but is only now being extensively pursued 共Huovila and Koskela 1998; Hawken et al. 1999; Horman et al. 2004兲.

Research Methodology Mapping the Delivery Process: Data Collection To capture and evaluate Toyota’s sustainable building delivery process, a modeling approach was developed to map the entire capital delivery process, i.e., programming through design, procurement, construction, handover, and operation. Extensive review of lean mapping techniques and current building process models revealed the importance of evaluating value and waste in process analysis 共Rother and Shook 2000; Rother and Harris 2002; Hines and Taylor 2000; Liker 2004兲. The features of the adopted modeling approach draw on the Integrated Building Process Model developed at Penn State 共Sanvido 1990兲. This model, based upon the IDEF0 modeling language, uses an input-activityoutput relationship to identify the key steps required to provide a facility to the end user. The power of this model is in the systematic rigor at which the entire process of building delivery is described, and the ability to adapt it to map process value and waste 共Horman et al. 2006兲. The first step in the adopted methodology was to understand value in terms of the process customer. As for most facilities, the building end user is the final customer at Toyota RE&F. The end

Fig. 2. Customer needs of the end user and the environment define value at Toyota

user needs include space, functionality, aesthetics, proper Toyota image, and price. A similar set of needs would exist for other end users. Value is generated when these needs are fulfilled. However, when a Toyota facility is built to be sustainable, the environment is introduced as an additional customer 共Horman et al. 2004兲. The environment’s needs include sustainable development principles such as minimal building impact, maximum building system efficiency, and a healthy and productive occupant environment. Again, value is generated by fulfilling this specific needs set. Fig. 2 shows how the needs of the end user and the environment are woven together to provide a framework for identifying and assessing how value is generated for sustainable facilities at Toyota. With a definition of value established, detailed process maps were then developed. These maps provide a pictorial representation at increasing levels of detail of the steps Toyota uses to deliver their capital facilities. Penn State researchers embedded themselves in the Toyota RE&F organization for five months meeting daily with the various departments to document their processes. Microsoft Visio was used to manage the extensive data obtained. Maps at three levels of detail were developed. The first level shows overall phases indicating where each department becomes involved in a project. The second layer documents resource 共people兲 and information flows. The third, and most detailed layer, shows the functions performed, inputs needed, and outputs produced. These maps capture the entire development process providing the foundation to assess the value generating and waste laden properties of each process activity. To ensure their accuracy, the maps were verified by each department and the entire organization. Data Analysis Analysis of the process maps was performed with three objectives in mind: 共1兲 Understand where value and waste are generated in the delivery process; 共2兲 understand the important features that are responsible for the successful delivery of Toyota’s sustainable buildings; and 共3兲 identify opportunities for continuous improvement of the Toyota RE&F delivery process. During the value assessment, each activity was scrutinized to evaluate whether it met the needs of either the end user or the environment. If RE&F could attribute no value in these terms to the activity, it was designated a waste. In some instances, an activity was found to be wasteful, but essential to achieve a value added outcome. In these cases, the activity was noted to be nonvalue adding. Lean principles state that nonvalue-adding activities are type two waste and should be the focus of long-term improve-

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Fig. 3. Level 1 of the Toyota capital delivery process

ment efforts 共Liker 2004兲. For the purpose of this research study, the aim of the value assessment was to identify all instances of process value and waste 共including nonvalue adding兲 in relation to Toyota achieving sustainable goals. In the future, a more detailed distinction of type one and type two waste would be a useful extension of this research. Having assessed where value and waste were generated in the delivery process, activities were then examined for their contribution to the sustainable goals for the project. The purpose was to provide an understandable breakdown of value-added activities that contribute to sustainable objectives during project delivery. Finally, the analysis focused on identifying opportunities for delivery process improvement. The purpose of this step was to reveal what process improvements in building project delivery look like. Model Validation To help validate the capability of the model to capture and reflect process attributes in the Toyota capital facilities program, a completed project was mapped and compared against the generic delivery process map. It was hypothesized that if the generic process map could capture the essence of a real project then this helped validate the diagnostic functionality of the mapping protocol. The project evaluated was the completed Lexus H/Q renovation. The project manager used our modeling protocol to document the process map for this project. This map documented a similar number of inputs, activities, and process outputs to the generic process map, suggesting the mapping protocol was comprehensive at documenting a real project. More importantly, however, the map comparison insightfully documented many of the major challenges on this project. The Lexus H/Q project was suspended for eight months until the 2003 fiscal year, resulting in supplementary rework in programming, and process dysfunction due to missing the Project Initiation phase of Toyota’s project delivery process. The map linked very clearly the downstream effects of these issues during design and construction. This was noteworthy for the post mortem of the project because it dispelled previously misunderstood and underdevelopment reasons for the suboptimal delivery performance that initially had included a faulty project team and mismanagement by the project manager.

Results Process Maps Fig. 3 shows the first level of Toyota’s capital delivery process. During the programming phases, projects are solicited by Real Estate and Facilities from various Toyota business units 共end users兲. Initially, these are general requirements and requests that RE&F uses to create a capital budget for the coming year. Once in the capital budget, the strategic needs of the business unit are assessed, project scope is planned, and a business case is devised for each project. Having received corporate sign off at this point, the project proceeds through Transition 1, which consists of a series of Project Initiation meetings to select a project team 共architect, consultants, etc.兲 and to hand the project off to that team for Project Implementation 共design and construction兲. There is nothing uniquely integrated about this phase of the delivery process which proceeds in a largely sequential manner. Transition 2 represents facility turnover at project completion. Relocations are a particular RE&F workgroup responsible for moving the business unit into their facility. In an effort to ease this transition, this group has become involved earlier in project implementation. Operations and Real Estate inherit the facility and are responsible for facility use and realty-related issues 共e.g., leases, etc.兲. Fig. 4 shows a sample of the second and third levels of the process map. These levels reveal progressively more detailed steps of the delivery process. The example shown is that of Business Case Development. The second level map 共top of Fig. 4兲 shows the basic steps of the phase, indicating who is the owner of the step 共in dark gray兲 and who will be involved 共in medium gray兲. The inputs and outputs at this level concern the critical information flow through the steps. Ownership, participation, and information requirements were not previously well defined in the RE&F organization and often led to delays, rework, and other waste in their process. The third level map 共bottom of Fig. 4兲 shows the detailed inputs, function and outputs needed in each step of the process. These are the same as the second level, but in more detail. Rules for modeling were used to provide coherency to the map. For example, for a function to be included on the map, it had to possess an input, either separately defined or the output of a pre-

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Fig. 4. Sample portion of Levels 共top兲 2 and 共bottom兲 3 of the Toyota capital delivery process

viously completed step, and an output that was used at another step in the delivery process. At this level of detail, the value and waste attributes of activities could be analyzed. Process Performance Analysis At the greatest level of detail, the process map identified a total of 23 inputs, 124 total activities, and 36 total process outputs. Of those 124 activities, the value assessment of the process map revealed 40 of those activities added value whereas 84 activities were wasteful, i.e., the current Toyota delivery process generates 32% value added for their customer base 共Table 1兲. By way of comparison, Horman and Kenley 共2005兲 in a large study demonstrated that projects average 50% wasted activities, although this analysis was confined to construction processes not taking account of other project delivery phases, like design. Manufacturing studies have empirically shown waste to be as high as 85–99% 共Stalk and Hout 1989; Hines and Taylor 2000; Liker 2004兲. The

Table 1. Quantitative Analysis of Value and Waste Steps in Toyota’s Capital Delivery Process

Function Capital planning Project strategy Real estate strategy Business case development Project initiation Project implementation Relocations Postproject occupancy Average over the total delivery process

Value added activity 共% of total activity兲

Waste and nonvalue added activity 共% of total activity兲

Baseline

Lexus

Baseline

Lexus

29 43 33 40

27 46 N/A 33

71 57 67 60

73 54 N/A 67

25 30 29 38 32

0 28 29 38 27

75 70 71 68 68

100 72 71 68 73

exact proportion of value added to waste is likely to vary depending on the underlying complexity of the process and whether activities are measured in terms of schedule or cost. What is most useful about the value assessment of the process map is that Toyota’s delivery process is not particularly efficient. In fact, Toyota has an opportunity to eliminate 68% of their project delivery activity to streamline their sustainable building delivery process. It is also interesting to evaluate where Toyota adds most value and where it is most wasteful. A notable capability of the map is that it is possible to conduct this evaluation of the total process 共not just phases or parts兲. Table 1 reveals that the processes where the greatest value was added were Project Strategy, Business Case Development, and Postproject Occupancy. These processes are not surprisingly high at generating value since they involve quite high levels of interaction with the end user 共business unit兲. What is perhaps surprising is that Project Initiation and Project Implementation 共i.e., design and construction兲 appear to add very low levels of value. Examples of the major waste found in design and construction included mismatched procurement of design and construction services so that excessive delays and rework occurred to form a coherent team. An excessively large number of small subcontractors were procured as a way of controlling costs at procurement, but at the expense of bidding delay, excessive rework, and reduced economies of scale and poor integration. These processes are the core of what the AEC industry does, i.e., design and construct buildings. These results suggest that this industry might not be very efficient in adding value. The process analysis also revealed critical wastes in Toyota’s capital facilities program. Table 2 outlines the significant delivery process wastes that were identified in this study. The total perspective and process orientation of the maps were critical to recognizing and understanding these wastes. Notably, the transitions identified in Fig. 1 were major bottlenecks in process flow for project delivery. As an example, the first process waste identified in Table 2 was largely the result of a small number of senior Toyota management overburdened with presenting the business case to corporate executives, and then initiating the project. Often projects approved in the Capital Planning budget were held in

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Table 2. Key Wastes as Captured by the Process Map Process waste

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Inconsistent flow through delivery process Complex activity and process sequences Lack of process transparency

Segregated department structure

Inconsistent feedback and continuous improvement mechanisms

Solutions developed to eliminate process waste Level process flow: Achieved through the identification, elimination, and resequencing of overburdening activities. This proved to reduce bottlenecking and improve process flow Elimination of excessive project parameters: Including instances of overproduction, redundancy, excessive checks/signoffs, and activities that did not generate outputs Project delivery plan: A simplified process map that clearly communicates the delivery process. This tool improved process transparency and helped to better manage customer expectations Integrate department workgroups: Emphasis was placed on increased involvement from O&M early in the delivery process, i.e., during project programming through design. This proved to ease downstream bottlenecking and help process flow Postproject evaluation (PPE): A revised PPE was developed and implemented. This tool enabled project performance and improvement opportunities to be consistently captured and evaluated

limbo for weeks before they transitioned to Business Case Development because of this overburdening. In other examples, some of the procedures adopted by Toyota reflected institutionalized waste, especially activities that were performed because that was the “Toyota approach.” An example of this is the three Project Initiation meetings performed. Although these had always been done, they could be combined to one or two meetings and reduce waste.

are not “tacked onto the project” but woven into the project. Savings elsewhere in the project can be used to offset these increases. Equipment costs can be justified through life cycle and operational savings. 3. Sustainable compatibility: Sustainable building features are aligned to site conditions and parameters during project programming. In addition, sustainable building features that are included in the project scope must be conducive to the operational purpose of the building. For example, photovoltaic cells made good business and sustainable sense on the South Campus project in southern California. Yet, use of this clean energy source was not suited to the climate of the Oregonbased port of Portland project. 4. Early selection of team members with sustainable experience: Teaming is a critical part of sustainable building delivery. At Toyota, project teams are formed early, and include specialty contractors and design teams with sustainable project experience. Bringing these disciplines to the table early in the delivery process engages critical process integration and allows system and environmental knowledge to be tapped as design begins. 5. Alignment of team member goals and project goals: In addition to selecting the project team early, Toyota spends time before the project commences to clearly define success for the project. Team members share their needs for project success and alignment is sought. This process provides a clear benchmark for direction throughout the project and for performance assessment at completion. These processes are employed regardless of whether LEED certification is being sought for a building or not. Seamlessly weaving the activities into Toyota’s delivery process allows sustainable outcomes to be realized at little or no extra cost. Improvement Ideas and Filter

Assessment of Toyota’s Sustainable Building Delivery Process Activities were then assessed for their contribution to the delivery of Toyota’s sustainable buildings. The process map was instrumental in recognizing the environmental value of Toyota’s capital facility program as many features were so embedded in the Toyota process that they were difficult to identify through other analysis techniques. One example of this is Toyota’s use of the business case to drive the achievement of sustainable goals. The established value criteria acted as a lens to assess how specific process activities documented by the map fulfilled the needs of the environment. Table 3 identifies the vital steps throughout the life cycle of Toyota’s delivery process and explains their valueadded 共i.e., lean兲 contribution. The lean elements of Table 3 can be distilled into five core value-added processes that contribute to sustainable objectives during project delivery. The hallmarks of Toyota’s success at sustainable building delivery include the following. 1. Early evaluation and adoption of environmental considerations: Sustainable objectives are evaluated and adopted very early in the Toyota delivery process, typically during project programming. This enables a clear understanding of sustainable objectives and generates upper management support. 2. Business case imperatives: Early evaluation and adoption of sustainable objectives allows project budgets to be aligned with environmental project goals. This significantly enhances the business case for sustainability as sustainable objectives

The delivery process map has been instrumental in analyzing Toyota’s success at sustainable building delivery, but has played an equally important role in revealing and focusing process improvement opportunities. Critical to the success of green facility delivery is to constantly challenge current levels of performance to continuously improve. Advances made by experienced teams in design and delivery efficiencies are being reinvested in sustainable facilities to offset the costs of more expensive, but efficient building systems. With 68% waste, Toyota’s delivery process is not particularly “lean” and represents a significant opportunity to achieve efficiencies to reinvest in the sustainability of their facilities. The importance of kaizen or continuous improvement to Toyota corporate culture has recently been discovered to be at the heart of the TPS 共Spear and Bowen 1999兲. Workers in the TPS have time deliberately carved out of their schedules to evaluate and experimentally test each process and activity in order to refine current practices before devising a targeted plan for improvement 共Spear and Bowen 1999; Ohno 1988; Shingo and Dillon 1989兲. Drawing on core lean theory that uses the scientific method to test and focus improvement ideas 共Spear and Bowen 1999; Spear 2004兲, an Improvement Ideas Filter was developed for Toyota RE&F to capture and evaluate ideas. Aligned with corporate RE&F business objectives, lean principles of continuous improvement, and environmental goals, the filter classifies improvement ideas and then assesses each against a series of tests. Table 4 shows the filter, a number of improvement ideas, and the results of their evaluation. Five categories of tests were used to analyze

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Table 3. “Lean” Element of Toyota’s Sustainable Building Delivery Process Strategy

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Programming Identify unique environmental opportunities

Steps taken to execute strategy

Overall value added

Understand the project needed, e.g., renovation, new construction, lease. Evaluate site, e.g., location, climate, urban/rural. Assess building type, e.g., distribution center, office, port. Analyze client culture, e.g., progressive, concern for environmental issues

Ensures that all environmental opportunities are identified and explored

Determine likely LEED certification

Determine if LEED is appropriate. Does budget allow for it? Understand culture surrounding project, e.g., users, government, and marketing opportunities

Early decision whether to seek LEED certification

Align sustainable features with project budgets

Understand first costs verses life cycle cost. Assess and understand any potential budget impacts. Calculate long-term operational savings

Business case for sustainability made

Select project team with sustainable experience

Require all RFP respondents to discuss relevant experience with sustainable facility delivery and how they will help RE&F achieve environmental goals

Demonstrates ability to achieve sustainable objectives

Develop a 1–2 page summary of the environmental initiatives regarding the project. Determine time and place for ecocharette. Distribute ecostatement

Communicates sustainable opportunities and objectives

Conduct design ecocharette

Develop environment project features based on identified opportunities. Establish understanding of goals throughout project. Seek additional information if necessary. Identify and take advantage of unique project features

Develops sustainable objectives that align with overall project goals

Revise ecostatement

Update ecostatement based on charette results. Review and realign with project goals if necessary; assess impact on business case

Finalizes project sustainable objective

Monitor on site sustainable programs

Review goals before and during construction. Educate team. Visit site to ensure proper adherence to sustainable initiatives

Ensures sustainable goals are achieved on site

Inform occupants and operation/maintenance about sustainable building features and corresponding maintenance requirements

Makes certain sustainable building features are not compromised

Assess and optimize building system performance to assure sustainable objectives are continually met

Ensures ongoing building systems performance

Design/Construct Generate ecostatement

Operate Educate maintenance staff and occupants Monitor operational performance

an idea: 共1兲 Promotion of RE&F mission; 共2兲 conformity to the project business case; 共3兲 adherence to Toyota environmental policies; 共4兲 elevation of facility sustainability; and 共5兲 capitalizing on Toyota corporate culture. The tests in each category assess specific attributes of the idea, e.g., the likely effect on budget or schedule 共Lapinski 2005兲. The results column is a simple pass rate 共e.g., for the first idea, 21 of 23 tests passed兲. Based on these results, the ideas are ranked to help prioritize them. The intent of the filter is to objectively and systematically focus employee attention on the ideas that will generate the greatest value to the organization. To test the filter, the two top ideas that passed through the filter were implemented and their process impact was assessed. The Postproject Evaluation was revamped to shorten the feedback loop to the project team by executing one additional evaluation at the end of design. Having implemented the new PPE process on three projects, follow-up surveys were performed that showed that the project teams found the revised approach very useful for recognizing deficiencies and enabling them the opportunity to make corrections before project completion. This is not possible with the original PPE at project completion. The second idea was

to increase project transparency by developing a project development plan to describe the project delivery process to the business unit 共end user兲. This document shows key project milestones, explains their purpose, highlights the environmental enhancements occurring, and identifies the points of end user participation and key decisions needed. Employed on two projects to help end user participation, end users were surveyed and indicated a strong preference for this tool to help them understand the process and make timely decisions so as not to unduly delay the projects. These results are documented in Lapinski 共2005兲.

Conclusions Many capital facility owners and building project teams make mistakes early due to inexperience on the unique and challenging requirements of green buildings. On Toyota’s South Campus project, a LEED Gold certified building was procured at no additional cost with respect to conventional facilities of similar size and scope. To understand Toyota’s success, the lean principles of

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Table 4. Continuous Improvement Filter Improvement idea 共idea classification: 1–flow, 2—complexity, 3–transparency, 4–Integration, 5–continuous improvement mechanism兲

1

5

X X X X

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3 3 1

2

3

4 4

4 5

3 2 1 2 1 2 2

Revise the Postproject evaluation process Identify project driver early in the process Better manage project expectations Increase interaction between design team and contractor throughout project process Streamline project delivery meeting structure and frequency 共i.e., kickoff meetings for SD, DD, and CD兲 Further integrate sustainable objectives into project delivery process Select core project team earlier in project process Utilize subcontractor expertise to improve project design and constructability Increase supplier input during design Advance end user education regarding sustainable building objectives Improve internal and external process communication Research then implement alternative project delivery methods Streamline the capital budgeting process Decrease business case development time Implement an integrated project team approach throughout Streamline the second delivery transition Work to standardize repetitive work

Category 1 Test 2 3

4

Category 2

1

Test 2 3

4

Category 3

1

Test 2 3

X X X X

4

Category 4

1

Test 2 3

4

Category 5

1

2

3

Test 4 5

X X X

X X X X X X X X X X X X X X X

X X X X X X

X X X X X X X X

X X X X

Total score rank 7 Yes

X X X

X X X X X X X X

X X X

X

1

16 70% 11 tied

X X X X X X X 19 83% 2 X X X X X X X 16 70% 11 tied

X X X X X X X X X X X X X X

X X X

6

X X X X X X X X X X X X X 21 91%

X X X X X X X X

X X X X

Results

X X X 14 61% 15 tied

X X X 17 74%

X X X X X X

8 tied

17 74%

8 tied

X X

X X X X

X X X X X X X 17 74%

8 tied

X X X X

X X X X

X X X X X X X 18 78%

3 tied

X X

X X X X X X X X X X

X X X X X X X X

X X 14 61% 15 tied

X

X X X X X X X 16 70% 11 tied

X X X

X X X X

X X 18 78%

X X X X X X X X

X X X

X X X X

X

X X X X X X X X

X

X X X X X X X 16 70% 11 tied

X X X X X X X X

X X X

X X X X X X X 18 78%

3 tied

X X X X X X X X

X X X

X X X X X X X 18 78%

3 tied

X X X X X X X X

X X X

X X X X X X X 18 78%

3 tied

X X X

X X X X X X

the TPS were utilized to map and assess value and waste within their sustainable building delivery process. The rigor at which the map was generated and assessed provided deep insight and understanding regarding the strategy and capabilities Toyota used to successfully deliver sustainable buildings. Apart from these successes, opportunities to eliminate process waste were also identified by the process map. The detail of these maps allowed evaluation of the valuegenerating and waste-laden properties of each process. While not being particularly lean overall, the process map analysis showed that Toyota employed a small number of key lean processes: 共1兲 Their decision to evaluate and adopt sustainable objectives very early in the process, even as early as capital budgeting; 共2兲 the alignment of sustainable objectives to the business case of the project; 共3兲 the identification and pursuit of building features that naturally align with sustainability; 共4兲 the selection of an experienced design and construction team early in the project, and 共5兲 investing time to align individual team member goals with project goals. The seamlessness of this approach is demonstrated by the

3 tied

16 70% 11 tied

fact that Toyota adopts precisely the same process regardless of whether projects pursue LEED certification or end up with few sustainable features. Although other process models have carefully documented the building delivery process, this modeling approach and resulting process map is one of the first to examine the entire sustainable building delivery process, from building inception through turnover. This enabled unique and critical information to be obtained and allowed the evaluation of the Toyota delivery process for sustainable buildings. Unique to this evaluation is the inclusion of both the end user and environment needs in relation to value and waste. The process map played a vital role in providing the means to identify and understand in clear terms the critical value added steps in Toyota’s delivery process for sustainable buildings. This map was vital for observing many of the features of Toyota’s project delivery program as the important features were not especially clear when observed through other methodologies. Through process improvement that targets increasing value and eliminating

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process waste, the insights gained at Toyota hold great potential for low-cost sustainable buildings throughout the AEC industry.

Acknowledgments

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The writers of this paper wish to thank Toyota Motor Sales Real Estate and Facilities, and the Lean and Green Research Initiative and the Partnership for Achieving Construction Excellence 共PACE兲 at Penn State for their support of this research.

References Arbulu, R., and Tommelein, I. 共2002兲. “Value stream analysis of construction supply chains: Case study on pipe supports used in power plants.” Proc., 10th Annual Conf. of Lean Construction, August 6–8, Gramado, Brazil, Universidade Federal do Rio Grande do Sul, Brazil. Ballard, G. 共2000兲. “Lean project delivery system.” Lean Construction Institute White Paper No. 8, Lean Construction Institute, Ketchum, Id. Ballard, G., and Howell, G. 共1998兲. “Shielding production: Essential step in production control.” J. Constr. Eng. Manage., 124共1兲, 11–17. Ballard, G., and Zabelle, T. R. 共2000兲. “Lean design: Process, tools, and techniques.” Lean Construction Institute White Paper No. 10, Lean Construction Institute, Ketchum, Id. Bremner, B., Dawson, C., Kerwin, K., Palmeri, C., and Magnusson, P. 共2003兲. “Can anything stop Toyota?” Business Week Online, 具http:// businessweek.com/magazine/content/03_46/b3858001_mz001.htm典 共June 9, 2005兲. Hawken, P., Lovins, A., and Lovins, L. 共1999兲. Natural capitalism: Creating the next industrial revolution, Little, Brown, and Company, Boston. Hines, P., and Taylor, D. 共2000兲. Going lean, Lean Enterprise Research Centre, Cardiff, U.K. Horman, M., and Kenley, R. 共2005兲. “Quantifying levels of wasted time in construction with meta-analysis.” J. Constr. Eng. Manage., 131共1兲, 52–61. Horman, M., Riley, D., Lapinski, A., Korkmaz, S., Pulaski, M., Magent, C., Luo, Y., Harding, N., and Dahl, P. 共2006兲. “Delivering green building project: Process improvements for sustainable construction.” Journal of Green Building, 1共1兲, 123–140. Horman, M. J., Riley, D. R., Pulaski, M. H., and Leyenberger, C. 共2004兲. “Lean and green: Integrating sustainability and lean construction,” CIB World Building Congress, May 2–7, Toronto, International Council for Research and Innovation in Building and Construction 共CIB兲, Rotterdam, The Netherlands. Huovila, P., and Koskela, L. 共1998兲. “Contribution of the principles of lean construction to meet the challenges of sustainable development,” Proc., 6th Annual Conf. on Lean Construction, August 13–15, Guarujá, Brazil. Koskela, L. 共1992兲. “Application of the new production philosophy to construction.” Technical Rep. No. 72, Center for Integrated Facilities Engineering, Stanford Univ., Stanford, Calif.

Lapinski, A. R. 共2005兲. “Delivering sustainability: Mapping Toyota Motor Sales’ corporate facility delivery process.” MS thesis, Architectural Engineering, The Pennsylvania State University, University Park, Pa. Lapinski, A., Horman, M., and Riley, D. 共2005兲. “Delivering sustainability: Lean principles for green projects,” ASCE Construction Research Congress (CRC), April 5–7, San Diego, ASCE, Reston, Va., 136–140. Liker, J. K. 共2004兲. The Toyota way, McGraw-Hill, New York. Ohno, T. 共1988兲. Toytota production system: Beyond large-scale production, Productivity Press, Portland, Ore. Pristin, T. 共2003兲. “Toyota’s new main campus: Green goes mainstream.” The New York Times, New York, C6. Pulaski, M., Pohlman, T., Horman, M., and Riley, D. 共2003兲. “Synergies between sustainable design and constructability at the Pentagon.” ASCE Construction Research Congress (CRC), March 18–20, Honolulu, ASCE, Reston, Va. Riley, D., Magent, C., and Horman, M. 共2004兲. “Sustainable metrics: A design process model for high performance buildings,” CIB World Building Congress, May 2–7, Toronto, CIB, The Netherlands. Rother, M., and Harris, R. 共2002兲. Creating continuous flow, Lean Enterprise Institute, Brookline, Mass. Rother, M., and Shook, J. 共1999兲. Learning to see, Lean Enterprise Institute, Brookline, Mass. Sanvido, V. E. 共1990兲. “An integrated building process model.” Construction Research Program Technical Rep. No. 1. The Pennsylvania State University, University Park, Pa. Shingo, S., and Dillon, A. P. 共1989兲. A Study of the Toyota production system from an industrial engineering viewpoint, Productivity Press, Cambridge, Mass. Smith, A. 共2003兲. “Building momentum: National trends and prospects for high-performance green buildings.” Rep. by the U.S. Green Building Council for the U.S. Senate Committee on Environment and Public Works, USGBC, Washington, D.C. Spear, S. J. 共2004兲. “Learning to lead at Toyota.” Harvard Bus. Rev., 82共5兲, 78–91. Spear, S. J., and Bowen, H. K. 共1999兲. “Decoding the DNA of the Toyota production system.” Harvard Bus. Rev., 77共5兲, 96–106. Stalk, G., Jr., and Hout, T. M. 共1989兲. Competing against time, Free Press, New York. Tommelein, I. D., and Li, A. E. Y. 共1999兲. “Just-in-time concrete delivery: Mapping alternatives for vertical supply chain integration,” Proc., 7th Annual Conf. on Lean Construction, July 26–28, Berkeley, Calif., University of California-Berkeley, Berkeley, Calif. Tommelein, I. D., and Weissenberger, M. 共1999兲. “More just-in-time: Location of buffers in structural steel supply and construction processes,” Proc., 7th Annual Conf. on Lean Construction, July 26–28, Berkeley, Calif., University of California-Berkeley, Berkeley, Calif. U.S. General Services Administration 共GSA兲. 共2004兲. “GSA LEED cost study: Final report,” Rep. No. GS-11P-99-MAD-0565, GSA, Washington, D.C. Womack, J. P., Jones, D. T., and Roos, D. 共1990兲. The machine that changed the world: The story of lean production, HarperPerennial, New York.

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International Journal of Scientific & Engineering Research, Volume 3, Issue 7, July-2012 ISSN 2229-5518

1

LEAN AND GREEN CONSTRUCTION Ritu Ahuja Abstract— Today, the construction industry is facing a number of problems which include cost overrun, completion delay, low productivit y, poor quality. These inherent problems need to be solved and taken care of in order to bring an overall change and improvement in the current scenario of the construction industries. The need for the change can only be resolved by the Lean construction and Lean project management approach. Today, people have started to be concerned about the 4 R’s i.e. Reduce, Recycle, Reuse and Regulate. In the recent years, eliminating the ‘concept of waste’ and creating a healthier environment through design and management has become a prime goal, thus involving the issues of sustaina bility in construction. The paper would bring out the deep connections of the lean and green philosophies, both seeking to reduce waste. It would explore as to how the lean strategy in the construction industries help to bring out a green and sustainable built environment. Index Terms— Lean Construction, green, Sustainable construction, sustainability, environment, sustainable development, lean principles.

——————————  ——————————

1.

INTRODUCTION

The construction industry plays a significant role in economic growth, both directly through its activities, and indirectly through the provision of buildings and infrastructures for the smooth functioning of businesses. However, the construction industry is highly challenged as a 3D‘s industry – dirty, dangerous and demanding. Lean production focuses on eliminating waste and maximizing productivity through the pull system, employee involvement, continuous improvement, etc. Much has been discussed about the waste elimination and productivity improvement that can be achieved by applying the lean concept. However, as the consideration of the environment is becoming an increasingly important part of the construction culture, there is a need to investigate the applicability of the lean concept to achieve environmental sustainability, which is often used interchangeably with the term ―green‖.

2.

THE PRACTICAL RELATIONSHIP BETWEEN LEAN METHODS AND SUSTAINABLE IMPACTS- THE LEAN DELIVERY PHASES-

The Lean Project Delivery system consists of four interconnecting phases extending from Project definition to Design, supply and assembly. (Fig.1) The Project Definition consists of three different modules: Needs and Value Determination, Design Criteria and Conceptual design. Defining value and waste is critical ————————————————

Assistant Professor, Amity School of Architecture and Planning, Amity University, Noida – 201301, Uttar Pradesh, India; Ph (0091) 8506051102; email: [email protected],[email protected]

in Lean production. Value management aims to maximize value and eliminate waste. Recently more studies have introduced the environment as an additional ―customer‖ for sustainable facilities (Horman et al., 2004; Lapinski et al., 2005). Minimal building impact, maximum building system efficiency, energy efficiency, waste reduction, and a healthy, productive environment for occupants are the key features of the lean and green construction. The social impact of facilities has been one of the critical concerns in the architecture industry. It is hard to measure the social impacts of facilities on humans and communities. Together with the economic and environmental bottom lines, the social bottom lines also included in Sustainability. Lean construction needs to identify sustainable values including economic, environmental and social values as important factors in implementing sustainable construction. Lean Design It is a process that includes various construction techniques and materials to produce value to an owner. This process is very important considering the impacts to the overall life of a facility. The green facilities can only be applied to its best in a design contributing to sustainable construction only if the use of green materials, resources and the construction technologies is comprehensively coordinated with each other. The impacts of this green facility phase on the Operation and Management phase are remarkable. One researcher suggests that a mere one percent of the initial costs in the early phase of a project address seventy percent of its life cycle costs (Romm, 1994). In order to minimize environmental impacts and energy consumption during construction of sustainable facilities, several Lean design methods could be implemented: Integrated Design (Whole system design), Design for Maintainability (DFM), Set-based Design, Target Costing, and 3D Modeling. Integrated Design is one of the most critical methods for sustainable construction (Hawken et al., 1999;

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International Journal of Scientific & Engineering Research, Volume 3, Issue 7, July-2012 ISSN 2229-5518

Riley, 2004; Horman et al., 2004; Lapinski et al., 2005).The most important feature of the Integrated Design method is to integrate various green materials and construction technologies by encouraging stakeholders in the design phase for maximizing the sustainability of a facility while reducing the need for energy, equipment, or resources.

2

Just-in-time (JIT) could also be regarded either as an environmentally-friendly method or the opposite. Justin-time reduces damage and materials (Riley et al., 2005). Moreover, this method may reduce the various sources of extra inventory but at the same time, however, the frequent transportation of inventory and materials may cause volatile organic compounds and CO2 emissions. Several Lean plants have recognized that a Just-In-Time strategy has caused more air emissions of volatile organic compounds in the plants, while contributing flexibility of operations and reducing inventory level (Rothenberg et al., 2001). Therefore, the plants have reconfigured some of their Lean management principles to reduce their air pollution emissions. Even though applications in the manufacturing industry and construction industry are not exactly the same, we need to notice the probabilities and possibilities of bad environmental impacts from Lean adaptation. The consideration from the holistic perspective is required to increase the sustainability of a construction project. Lean Assembly

Fig. 1. The Lean Project Delivery System- The four interconnecting phases extending from project definition to Design, Supply and assembly.

In order to minimize environmental impacts and energy consumption during construction of sustainable facilities, several Lean design methods could be implemented: Integrated Design (Whole system design), Design for Maintainability (DFM), Set-based Design, Target Costing, and 3D Modeling. Integrated Design is one of the most critical methods for sustainable construction (Hawken et al., 1999; Riley, 2004; Horman et al., 2004; Lapinski et al., 2005).The most important feature of the Integrated Design method is to integrate various green materials and construction technologies by encouraging stakeholders in the design phase for maximizing the sustainability of a facility while reducing the need for energy, equipment, or resources. Design for Maintainability (DFM) is a design strategy focusing on the reliability and ease of maintenance of a facility (Dahl et al., 2005). These methods increase the importance of O&M in the design phase of a facility. Operations & maintenance (O&M) costs are the largest portion of the total expenditures over the life of the facility, typically accounting for 60-85% of the life cycle cost. The safety and wellbeing of the occupants and of a community can be ensured by addressing social issues during the design phase in a sustainable construction project. Moreover, these social benefits may improve external images of the sustainable construction project. Lean Supply

One of the most successful procurement methods that can be adopted to achieve sustainability is the Prefabrication. Economic, social, and environmental indicators from (Horman et al, 2005) examined the impacts of prefabrication for purposes of sustainability using these indicators (Horman et al., 2005 in Luo et al., 2005). The features of prefabrication on sustainable constructions include: - Increased potential of improved supply chain integration of green materials - Safer working conditions - Reduced environmental impact due to transferring workers, machines, staked materials, temporary structures and onsite activities to a prefabrication plant - Easier recycling of materials in an off-site environment - Enhanced flexibility and adaptability - Reduced overall life cycle cost - Reduced economic impact in local communities. Prefabrication may have both sustainable benefits and disadvantages depending on the exact conditions of a project. These impacts fall into three categories: economic, social, and environmental. Thus, economically, one advantage is the reduced cost of prefabricated units as opposed to on-site units. Socially the working conditions are safer and more stable in prefabricated construction than they are on-site. Environmentally, this method may improve the supply chain for green materials, one aspect of green facilities. Yet, there are some problems as well. Economically, and socially, less local labour is needed, thus the salaries of the workers do not contribute to the local economy. Environmentally, this process may consume more energy for transportation of prefabricated products and emit more air pollution.

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A contractor implementing sustainable construction should identify both benefits and disadvantages of prefabrication and reference them for the selection of the best procurement method using a holistic view over the life cycle of a project. Kaizen, which means continuous improvement in Japanese, is a core component of Lean production not only for economic purposes, but also for social and environmental purposes in sustainable construction. Kaizen plays a key role in improving the current status for sustainable construction. All sustainable indicators may be improved through Kaizen. Another potential tool for sustainable perfection is Kaikaku. Kaikaku (Kaizen events), means a rapid process of improvement, is a team activity designed to eliminate waste and make rapid changes for product and process improvement in the workplace. This strategy is employed to get workers with multiple organizational functions on different levels to unite in improving processes and addressing problems. When implementing chosen improvements, the team rapidly employs inexpensive solutions usually within three days. Kaikaku can create reduced pollution and material waste. Environmental Health and Safety staff must participate in Kaizen events due to the possibility of non-compliance and exposure of workers to hazards. Suggestions may be made by EHS staff to facilitate the process (US EPA, 2006).

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the sustainable construction of a facility, while several Lean construction practices reveal no relationship or negative relationships. Like most industrial processes, current construction practices are linear. They use energy and natural resources, convert them to the built environment, and discharge waste. The large quantities of debris left over from demolished buildings are examples of waste from a linear process. Experts recommend a cyclical construction process that puts a greater emphasis on recycled, renewed, and reused resources. This cyclical construction approach should be accompanied by reductions in energy and resource use. The cyclical method could conceivably reuse much of a discarded building to erect a new one in its place. The adoption of this concept is likely in developing nations only if industry, academia, and government join forces and address it as a long-term goal, but with a plan for gradual, measurable progress towards it attainment. The Lean principles emphasise on eliminating process and material wastes and which can further result to the green construction which emphasise on the energy efficiency and the cost efficiency. The Lean and green Construction philosophy can tremendously improve the needs and result in high productivity of the construction industry. The lean and green theories both compliment each other. Lean construction is all about removing waste from the construction process, thus making it most efficient. Green construction also emphasises and focuses on the removal of waste from the construction process but also adds an environmental dimension to lean construction. The green construction in addition to the theories of lean construction also focuses on the recycling, reusing of the resources thus making the process and the project cost efficient and most productive.

Fig. 2. Lean Methods and Sustainable Impacts – The quantitative assessment on the sustainability of a construction project.

Figure 2 illustrates a quantitative assessment of the previously discussed methods on the sustainability of a construction project. Most lean construction methods provide positive economic impacts for sustainable facilities while showing several no-impacts or negative impacts on social and environmental aspects. The table shows concrete relationships between the Lean construction methods and

Fig. 3. Relationship between sustainable development and Lean production – The four interconnecting phases of Lean Project delivery System.

In the figure 3, the four interconnecting phases of the Lean Project Delivery System (LPDS) extending from project definition to design, supply, and assembly are used to illustrate the Lean construction process (Ballard, 2000).

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Addressing sustainable issues, such as economic, social, and environmental values as the requirements of an owner, Lean may act from the project definition to the construction phase for a sustainable facility. Lean principles can be implemented in the design phase of the project to attain cost reduction and enhance sustainability. Value Stream mapping is a good example of making a project most efficient from the design phase to the construction phase. The value stream mapping (VSM) is a tool created by the lean production movement for redesigning the productive systems. A value stream map is a complete model of the project that reveals issues hidden in current approaches. Value stream maps can be understood as process flow charts that identify what action releases work to the next operation.

3.

CONCLUSION AND RECOMMENDATION

The research tries to bring out the need for the implementation of lean philosophy in the construction industry. The values and the principles of the Lean construction and clearly discussed and compared with the present scenario of the industry. The main reason for the evolution of Lean Construction is the incompleteness of the typical construction followed today. Lean Construction should be adapted and considered as it can solve many problems of the construction industry and the project management as the cost over run, poor quality and the delays. The importance of environmental aspects cannot be separated from the lean construction as they add value to each other when combined and used correctly. The methods of lean construction should be extended to environmental planning to help improving the efficiency of the production management process. In this paper, most of the lean construction methods and the green construction methods are studied and examined. Although there are many other lean construction methods which are not been examined for sustainability, but if studied in future, will surely have a possibility for sustainable purpose.

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comparison of visions from various countries‖ . CIB Report 225, Rotterdam. [6] Charles J. Kibert (2008), Sustainable Construction, Green building Design and Delivery, second edition. [7] Cusumano, M.A. (1994). ―The Limits of ‗Lean‘,‖ Sloan Management Review, vol. 35, no. 4, Summer; pp. 27-32. [8] Degani, C.M. and Cardoso, F.F. (2002). ―Environmental Performance and Lean Construction Concepts: Can We Talk about A 'Clean Construction'?‖ Proceedings IGLC-10, Gramado, Brazil. (Conference proceedings) [9] Green S. D; ―The Future of Lean Construction: A Brave New World‖, International Conference on Lean Construction; Brighton; 2000. (Conference proceedings) [10] Helper, S. and Clifford, P. (1997). ―Can Green Be Lean?‖ paper presented to the Academy of Management meetings, Boston, MA [11] Horman, M.J., Riley, D., Pulaski, M.H., and Leyenberger, C. (2004). "Lean and Green: Integrating Sustainability and Lean Construction." CIB World Building Congress, Toronto, Canada. [12] Howell G.A.(1999), ― What is Lean Construction-1999‖ 26-28 July 1999, University of California, Berkeley, CA, USA. (Conference proceedings) [13] Howell G.A.; Ballard G. (1999), ―Bringing light to the dark side of Lean Construction‖, International Conference on Lean Construction; Berkley . (Conference proceedings) [14] Huovila, P. and Koskela, L. (1998). ―Contribution of the Principles of Lean Construction to Meet the Challenges of Sustainable Development” Proceedings IGLC-6 Guaruja, Brazil . (Conference proceedings) [15] Jin-Woo Bae and Yong-Woo Kim (2007), ―Sustainable Value On Construction Project And Application Of Lean Construction‖, Proceedings IGLC-15, July 2007, Michigan, USA. (Conference proceedings) [16] Lapinski, A., Horman, M.J., and Riley, D. (2005). ―Delivering sustainability: lean principles for green projects‖ Proceedings of the Construction Research Congress, San Diego, California. (Conference proceedings) [17] Luo, Y., Riley, D., and Horman, M.J. (2005). ―Lean Principles for Prefabrication in Green Design-Build (GDB) Projects‖ Proceedings IGLC-13 Sydney, Australia. (Conference proceedings) [18] Wu Peng and Low Sui Pheng (2011), ―Lean and green: emerging issues in the construction industry – a case study‖ 20-21 Sep 2011, EPPM, Singapore

REFERENCES [1] Ballard G., Howell G. (1994), ―Implementing lean construction: Improving downstream performance‖. [2] Ballard G., Howell G. (1998), ―Implementing lean construction: Understanding and Action‖, Presented at the Annual Conf. International Group for Lean Construction. [3] Ballard, G. (2000). ―Lean project delivery system.‖ Lean Construction Institute White Paper No. 8, Lean Construction Institute, Ketchum, Id. [4] Ballard G & Howell AG. (2003) Lean Project Management. Building Research and Information, 31(2), 119-113 [5] Bourdeau, L., Huovila, P., Lanting, R., and Gilham, A. (1998), ―Sustainable Development and the Future of Construction- A IJSER © 2012 http://www.ijser.org

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AicQoL 2013 Langkawi AMER International Conference on Quality of Life Holiday Villa Beach Resort & Spa, Langkawi, Malaysia, 6-8 April 2013 "Quality of Life in the Built and Natural Environment"

Sustainability through Lean Construction Approach: A literature review Mohd Arif Marhani a*, Aini Jaapara, Nor Azmi Ahmad Baria, Mardhiah Zawawib a

Faculty of Architecture, Planning and Surveying, Universiti Teknologi MARA, Shah Alam 40450, Malaysia Faculty of Civil and Environmental Engineering, Universiti Tun Hussein Onn, Batu Pahat 86400, Malaysia

b

Abstract Lean construction (LC) is excellent in managing the construction process and achieving the by eliminating waste. The objectives of this paper are to provide with fundamental knowledge of LC and highlight the barriers of its implementation. The literature reviews has been conducted through relevant databases. It was found that there is a need for more holistic approaches to be adopted in LC implementation such as health and safety, and six sigma. A systematic training and research are also found vital to provide good interaction and collaboration with the stakeholders. LC is also capable to enhance sustainability in construction thus the quality of life for future Malaysian construction industry. © 2013 The Authors. Published by Elsevier Ltd. Open access under CC BY-NC-ND license. © 2013 The Authors. Published by Elsevier Ltd. Selection and peer-review under responsibility of the Association of Selection and/or peer-review under responsibility of the Association of Malaysian Environment-Behavior Researchers, Malaysian Environment-Behaviour Researchers, AMER (ABRA Malaysia). AMER (ABRA malaysia).

Keywords: Lean Construction; sustainable development; quality of life; Malaysian construction industry

1. Introduction Sustainability has been defined as economic growth that meets the current generation compromising the opportunity and the potential for future generation needs (WCED, 1987 and El-Zeney, 2011). Sustainable construction is also regarded as a way forwards for the construction industry to achieve sustainability in development, while taking environmental, socio-economic and cultural issues into consideration (Shafii et al., 2006). In order to accelerate the sustainability awareness among construction players, the government of Malaysia has allocated RM 20 billion in the Budget 2010 (Ministry of Finance,

* Corresponding author. Tel.: +6-03-55444376; fax: +6-03-55444353. E-mail address: [email protected].

1877-0428 © 2013 The Authors. Published by Elsevier Ltd. Open access under CC BY-NC-ND license. Selection and/or peer-review under responsibility of the Association of Malaysian Environment-Behavior Researchers, AMER (ABRA malaysia). doi:10.1016/j.sbspro.2013.07.182

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2012). In the budget, emphasise and promotion on the green buildings initiatives have been highlighted with attention in its ability to reduce the overall cost while maintaining the quality of environment. Earlier on, the government has launched the National Green Technology Policy to provide guidance towards the management of a sustainable environment (The Star Online, 2009). Hence, Budget 2010 is a continuity of the earlier green policy formulated by the government. In materialising this effort, the construction industry is urged to move from traditional wet construction method towards environmental friendly, energy efficient and less waste generation methods of construction (Abdullah et al., 2009). To achieve as a developed nation status in 2020, the great demands on the infrastructure projects in Malaysia has resulted in a large quantity of construction waste (Begum et al., 2010) which comprises of 28.34% wastes generated from the construction activities (Mohd Nasir et al., 1998). This phenomenon called the urgency to the industry to change its current practices at reducing objectives in term of increasing the and eliminating wastage. Due to its great potential in fulfilling value and productivity of a construction project, LC is seen as an alternative approach that can be implemented to the construction industry. LC is a concept derived from manufacturing industry (Salem et al., 2006 and Koskela, 1992), adopted in construction with its main aims to minimise waste in the construction projects. Yahya and Mohamad (2011) concluded that LC is a proven method in managing and improving the construction process, hence profitability can be delivered by using the right principles and resources as well its ability to deliver things right the first time. This paper is aimed to provide the background literature of LC and future direction of LC in Malaysia. The objectives of this paper are to provide the fundamental knowledge of LC and highlight the barriers of its implementation. An extensive literature reviews have been conducted by retrieving related articles from journals ranging from 1992 to June 2012. From the literature search, it was found that LC has the ability in improving the performance of construction projects particularly in reducing site waste, construction time and overall construction cost, improving quality of the projects and environmental as whole. 2. Fundamental knowledge of LC From the literature reviews conducted, many definitions of LC have been discovered indicating the positive growth of lean methodology as well as its diversity. The definitions stated below would best describe the methodology and application of LC:Table 1. Definition of LC Definitions

Keywords

Authors

LC is a production management based approach to project delivery - a new way to design and build capital facilities. Lean production management has caused a revolution in manufacturing design, supply and assembly. LC extends from the objectives of a lean production system - maximise value and minimise waste - to specific techniques and applies them in a new project delivery process

Production management based; maximise value and minimise waste

Lean Construction Institute (2012)

Lean construction is the practical application of lean manufacturing principles, or lean thinking, to the building environment

Practical application to building environment

Lukowski (2010)

Lean is about achieving a balanced use of people, materials and resources. This allows companies to reduce costs, eliminate waste and deliver projects on time and it is not about trimming everything to the bone and squeezing more out of what is left.

Balanced use of people, materials and resources; reduce costs, eliminate waste and deliver projects on time

Lim (2008)

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Set of techniques; a discourse; a socio-technical paradigm; a cultural commodity

Green and May (2005)

LC is a big scale of adaptation from the Japanese manufacturing principles and the concept is implemented to the construction process

Manufacturing principles; construction process

Bertelsen (2004)

Lean construction is much like the current practice as the goal of better meeting customer needs while using less of everything

Meeting customer needs; less of everything

Howell (1999)

Advantages of the new production philosophy in terms of productivity, quality, and indicators were solid enough in practice in order to enhance the rapid diffusion of the new principles

Philosophy of productivity; quality

Koskela (1992)

set

-

Koskela (1992) introduced the philosophy of productivity and quality to the construction industry, aimed to improve the rapid diffusion of the new principles to the construction process. Generally, this new production philosophy is an adaptation from the manufacturing industry (Bertelsen, 2004; Lukowski, 2012; Lean Construction Institute, 2012), which requires specific key concepts or techniques to be implemented in project delivery. On the other hand, most of the researchers emphasised that LC concept is all about minimising construction waste (Howell, 1999; Lim, 2008; Lean Construction Institute, 2012) (Howell, 1999). Lim (2008) viewed that lean is about achieving a and meeting balanced use of resources, which allows the organisation to reduce costs, eliminate waste and deliver projects on time. Lean Construction Institutes (2012) further emphasised that the objectives of lean is to maximise value and minimise the wastage using a specified techniques and applies them in the new project delivery. Hence, LC can be regarded as a continuous improvement in the construction process, aimed at reducing waste of resources while increasing the value of the project to the client. Holistic approaches to the key concepts can be added and synergised in order to move towards sustainable and greener environment. Lean Construction Institute (2012) defined that LC is a production management based, a new way that . related effort to cost saving, ensuring high quality of the end product, boosting confidence level and safety of the construction workers; and maintaining the sustainability of the project itself. Conversely, Green and May (2005) viewed that this concept is a socio-technical paradigm that valuable to the cultural commodity. According to Koskela (1992), there were 11 basic principles to LC, which were to reduce the share of non value-adding activities, increase output value through systematic consideration of customer requirements, reduce variability, reduce cycle time, minimise the number of steps, parts and linkages, increase output flexibility, increase process transparency, focus control on the complete process, build continuous improvement into the process, balance flow improvement with conversion improvement and benchmarking. Later, Womack and Jones (1996) have simplified further the LC principles stated by Koskela (1992) into five LC principles, which are specified the value stream, make the value-creating flow, establishing client pull at the right time and pursue perfection for continuous improvement. These five principles are further confirmed by Lim (2008), Lean Enterprise Institute (2009) and Bashir et al. (2011) as able to be implemented to the total flow process and its sub-process in the construction industry. On top of that, by implementing these five principles would needs. lead the least amount of accomplishment, materials and resources while maintaining the

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3. Key concepts of LC Many established researchers such as Abdullah et al. (2009), Jorgensen and Emmitt (2008), Lim (2008) and Koskela (1992) have confirmed that LC offers many benefits when implemented in the construction projects. The main advantage is construction companies could cut down the construction cost due to use of correct materials and less waste in the sites (Suresh et al., 2011) due to proper project planning. Besides, by having a proper project planning, it would shorten the duration of the construction project and promote the quality and sustainability of the project itself. There are many key concepts or tools of LC that can be adopted throughout the project phases by the stakeholders. In earlier stage of its implementation, Koskela (1992) proposed three principles of production philosophy to be used at early project phase, which include tools circles), a manufacturing method and a management philosophy (i.e. Just-In-Time (JIT) and Total Quality Control (TQC)). Some of the examples of the key concepts are JIT, TQC, Total Productive Maintenance (TPM), Employee involvement, Continuous improvement, Benchmarking, Time based competition, Concurrent engineering (CE), Value based strategy (or management), Visual management, Reengineering and Lean manufacturing. In addition, Alinaitwe (2009) has simplified and depicted the key concepts of LC included JIT, Total Quality Management (TQM), Business Process Re-engineering (BPR), CE and Last Planner System (LPS); Teamwork and Value Based Management (VBM) (Harris and McCaffer, 1997). Salem et al. (2005) study evaluated the effectiveness of six LC key concepts to the University of . The data collection methods included observations on sites, interviews, questionnaires and documentary analysis. The key concepts involved were LPS, increased visualisation, daily hurdles meetings, first run studies, 5s (housekeeping) process and fail safe for quality and safety. Based on the findings, the implementation of 5s process and fail safe for quality and safety did not meet the expectations due to increase of the budget. There was a need for behavioural changes and training for effective use of key concepts. The rest of the key concepts selected for the project were either ready to use, or were recommended with some modifications. Similarly, Adamu and Abdul Hamid (2012) study investigated LPS using four key concepts and tested them in the construction of housing units in Yobe State Government of Nigeria. Due to some constraints, 5s was not tested. The data collection methods included direct involvement in the production management, interviews and questionnaires. Based on the findings, effective training and full implementation of LPS and partial implementation of the other key concepts have reduced and eliminated waste on site. It was also found that there was a need for cooperation of top management in order to improve the interest of LC amongst the stakeholders. Meanwhile, Suresh et al. (2011) introduced nine primary key concepts of LC that could be implemented in the LC practice. These key concepts were essential to the implementation of LC, which are LPS, productive meetings, increased visualisation, off-site prefabrication, 5s/5C, mistakeThe conclusion of the proofing/poka-yoke, root cause ana study showed that there is no need to use all of these key concepts in the construction project. The literature search has also found that there is a demand for more holistic approaches to be integrated in the existing LC key concepts application with other concepts. Bashir et al. (2011), introduced health and safety approach in the implementation of lean principles. The OHSAS 18001 could be incorporated with the key concepts of LC. OHSAS 18001 has been tested and internationally recognised to improve health and safety performance of the construction company. As a result, by having a safer and conducive workplace at sites, it would increase the productivity of the project and gave job satisfaction to the client.

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Moreover, by using LPS as a basis of LC approach, Abdelhamid (2003) suggested Six Sigma application opportunities in construction projects. Generally, Six Sigma is an organised and efficient process for strategic process improvement and new product and service development that relies on statistical methods and the scientific method to make significant reductions in customer defined defect rates (Linderman et al., 2003). The existence of Six Sigma as a continuous improvement technique in a project would provide combined, coherent and holistic approach to continuous improvement of the project (Pepper and Spedding, 2010). From the literature review, Environmental Management System (EMS) shared the same goal as lean concept, which is reducing waste. Basically, EMS provides an effective framework on the environment that can assist companies in fulfilling their responsibilities towards protecting the world environment (Gbedemah, 2004). By integrating EMS to LC key concepts in the construction sites, it would maximise However according to Puvanasvaran et al. (2011), the potentials of both integration remain unexplored since changes within the business environment and innovative technologies can widely impact operational process and procedures. Therefore, most of these concepts are interconnected and it is important to understand all the key concepts of LC, which may improve performance while minimising construction waste (see Fig. 1). The concept. Hence, it is important for the stakeholders to responsible and chooses the best approach of the key concepts that right to be implemented in their construction sites.

Six Si x Si Sigm gmaa gm

Key Ke y co conc ncep ep pts of LC C

Heal He alth lth & saffet ety ty

Just-In I -Time Total Quality Management Bus usin ines esss Pro roce cess ss Reengi en gine neer erin ingg Conc Co ncur urre rent nt Engi En gine neer erin ingg Las astt Pla lann nner er System Teamwork Value Based Management

Enviro Envi ronm nmen enta tall Manage Mana g mentt ge System

Fig. 1. Key concepts of LC

Maaxiimi M mise ise val alue lue & Miniimi mise ise was astte te

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Table 2. Key concepts of lean construction in the construction process Authors

JIT

Small et al. (2011)

TQM

BPR

Pre-

Design

construction Construction

CE

LPS

Teamwork

VBM

Health & safety

Six Sigma

EMS

Preconstruction Construction

Puvanasvara n et al. (2011)

Constru ction

Seppanen et al. (2010)

Construction

Pepper and Spedding (2009)

Preconstruction Construction

George and Jones (2008) Salem et al. (2006)

Pre-

Pre-

construction

construction

Construction

Construction

Construction

Construction

Mohd Yunus (2006)

Construction

Summers (2005)

Preconstruction Construction Use

Excellence (2004)

Construction

Bertelsen (2004)

Construction

Abdelhamid (2003)

Preconstruction Construction

Koskela (1992)

Construction

Design

Construction

Pre-

Use

construction Construction

Source: Adopted and modified from Marhani et al. (2012)

Meanwhile, Table 2 shows the interaction of key concepts of LC in views to the construction phases, which are preparation, design, pre-construction, construction and use (RIBA Plan of Work, 2012) derived from Koskela (1992), Abdelhamid (2003), Bertelsen (2004), Excellence (2004), Summers (2005), Mohd Yunus (2006), Salem et al. (2006), George and Jones (2008), Pepper and Spedding (2009), Seppanen et

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al. (2010), Puvanasvaran et al. (2011) and Small et al. (2011). From the above table, it can be concluded that pre-construction and construction stages are the best time to integrate the key concepts of LC as suggested by the majority of the researchers. This is due to their criticality in determining resources for the project during pre-construction (Koskela, 1992) and eliminating of construction waste during construction (Yahya and Mohamad, 2011). The key concepts of LC should be introduced at the earliest stage of the construction projects and involvement of the stakeholders should be continued throughout the entire construction process. By doing so, the stakeholders are capable in identifying the construction waste and diminishing volatility of a project earlier. 4. Barriers in implementation of LC Based on the literature review, it can be summarised that there are seven main barriers in implementing LC (see Fig. 2). Aspects such as managerial, technical, human attitude, the process of LC, educational, government and financial are among others of the main barriers. According to Abdullah et al. (2009) and Mossman (2009), lack of commitment from top management of a company was one of the main barriers in implementing LC. This barrier referred to various aspects that are related to the support shown by the top management in an organisation. As mentioned earlier by Kim and Park (2006), it was found that many construction projects are facing lack of support from the top management. In addition, lack of communication among stakeholders is also occurred in the construction projects (Abdullah et al., 2009). Hence, it will lead to the disruption and ineffectiveness on the delivery and coordination system. Without continuous supports from the top management, the stakeholders involved in the construction industry may face numerous difficulties in adopting LC concept. Besides, the top management of a construction company should overcome this breakdown in communication so that it will not contribute to low productivity and quality of the projects. Alinaite (2009) highlighted that lack of buildable designs was one of the main barriers under technical aspects. In addition, certainty in the production process and provision of benchmarks were also contributed as the main barriers during implementation of LC. Meanwhile Tindiwensi (2006) found that most of architectural designs were lacked of constructability elements due to the limited knowledge about construction practices and the separation of design from construction contributed to a breakdown of the production process during construction. This will give impact in the implemention of LC specifically to ll stakeholders should involve from the pre-construction stage and taking into consideration the buildability and constructibility of design and process. By doing so, changes on designs duringconstruction stage can be avoided that could disturb the production process. Howell (1999) added that human attitude is one of the main aspects that slowed down the execution of LC in the industry, especially during the physical implementation phase. According to Kim and Park (2006), the attitude of the stakeholders concerned in a construction project towards the LC concept was a sensitive factor that in actual fact influenced the success of implementing LC concept. Abdullah et al. (2009) further explained that the attitude here referred to the tendency regarding intent, commitment and co-operation that needed to be presented within the stakeholders if they wanted to implement LC successfully. This kind of thinking will thus determine their performance of work and will affect the productivity of a construction project. In addition, the lengthy implementation period of LC process was regarded as the barriers in implementing LC. Based on Kim and Park (2006), it was discovered that the implementation of LC in construction projects had resulted in too many meetings and information needed for discussions. Moreover, these meetings had to be held regularly and took up too much time when poorly managed. This occurs especially during the pre-construction stage but if this situation is well managed, it will definitely

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generated profit and positive effects to the construction company itself especially on boost up their reputation. The stakeholders involved in a construction project needed to be given ample training to enable them to possess the necessary knowledge and expertise in implementing LC concept (Abdullah et al., 2009; Alinaitwe, 2009 and Mossman, 2009). Inadequate exposure to the requirements for LC implementation was also regarded as barriers (Abdullah et al., 2009 and Alinaitwe, 2009) in LC implementation. The training given has to be balanced with the understanding the concept and principles of lean as well as comprehending the key concepts required to undertake the LC concept. Furthermore, training and educating the employees may take time and effort. Hence, top management should play an important role to expand training and education understanding at intensifying of LC concept. Finally, inflation due to unsafe f markets condition for construction, additional construction cost and poor salaries of professionals (Olatunji, 2008) were the barriers for financial aspects. Lack of incentives or reward systems in a construction project also led to the barriers in LC wide implementation (Alinaitwe, 2009). Sufficient sources of funding is a must to ensure the construction project runs smoothly. The provision of contingency cost will help the construction project from inflation or additional construction cost due to instability of the construction markets.

Mana Mana Ma nage g riiall ge Fina Fi nanc na nciia nc i al ial

Tec echhn hnic hni icall Barr Ba rrie rr iers ie rs in impl im plem lemen enti ting ti ng LC Huma Hu mann attti atti tittud tude de

Gove Gove Go vern rnme rn ment me nt

Educ Ed ucat uc atiio at iona iona nall

Proc P roc oces esss of es of LC

Fig. 2. Barriers of LC

5. Conclusion Based on the above discussion, it was shown that there is a need for more holistic approaches to integrate LC key concepts with other significant aspects, such as health and safety, six sigma and EMS. From the literature review, it was discovered that by introducing health and safety and six sigma assessment to a construction project will facilitate the construction company in managing and assuring their health and safety risks, dealing with qualities and strategies, thus improving their performance. In as well as minimising construction waste. The contractors should use c as most of the key concepts are interconnected between each others. To date, research conducted on standard procedure of LC key

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concepts is scarce; hence there is a need for a research to be conducted on this potential area. Furthermore, the potentials of integration of health and safety, six sigma and EMS to the key concepts of LC are remain unexplored. Based on the above discussion, there are seven main barriers during implementation of LC, which are managerial aspects, technical aspects, human attitude aspects, aspects of process of LC, educational aspects, government aspects and financial aspects. Thus, good strategies play a vital role when implementing LC in order to overcome these barriers. Among others are the development of systematic training and research actions on LC, and collaboration among construction companies. A proactive interaction between stakeholders can be inculcated, which resulted in a healthy competitive environment among the collaboration companies. Through LC implementation in the local construction management processes, it is hoped that it will be able to accommodate the industry with the new knowledge of LC towards sustainable and greener future of the Malaysian construction industry. Future research in a similar area will be conducted on construction organisations that have implemented LC concept by observing their practices on site. From the research, with appropriate methodology the actual key concept adopted in the construction projects can be investigated. Further suggestion on the possible other tools could also be proposed to the industry for value adding its existing LC implementation. References Abdelhamid, T.S. (2003). Six-Sigma in Lean Construction Systems Opportunities and Challenges. Retrieved 26 August 2012 from http://www.leanconstruction.dk Abdullah, S., Abdul Razak, A., Abu Bakar, A. H. & Mohammad, I. S. (2009). Towards Producing Best Practice in the Malaysian Construction Industry: The Barriers in Implementing the Lean Construction Approach. Retrieved 26 August 2011 from http://eprints.usm.my Adamu, S. and Abdul Hamid, R. (2012). Lean construction techniques implementation in Nigeria construction industry. Canadian Journal on Environmental, Construction and Civil Engineering, 3, 4, May 2012. Alinaitwe, H.M. (2009). Prioritising Lean Construction Barriers in Uganda's Construction Industry. Journal of Construction in Developing Countries, 15-30. Bashir, A.M., Suresh, S., Proverbs, D. & Gameson, R. (2011) A critical, theoretical, review of the impacts of lean construction tools in reducing accidents on construction sites In: Egbu, C. and Lou, E.C.W. (Eds.) Procs 27th Annual ARCOM Conference, 5-7 September 2011, Bristol, UK, Association of Researchers in Construction Management, 249-258. Begum, R.A., Satari, S.K., and Pereira, J.J. (2010). Waste Generation and Recycling: Comparison of Conventional and Industrialized Building Systems. American Journal of Environmental Sciences, 6(4), 383-388. Bertelsen, S. (2004). Lean construction: where are we and how to proceed. Retrieved 26 August 2011 from http://www.kth.se El-zeney, R.M. (2011). Towards sustainable interior design education in Egypt. Asian Journal of Environment-Behaviour Studies, 2, 61-72. Excellence, C. (2004). Effective teamwork: a best practice guide for the construction industry Constructing Excellence , 1-20. Gbedemah, F.S. (2004). Environment Management System (ISO 14001) Certification in manufacturing companies in Ghana: prospects and challenges. Retrieved 26 August 2012 from http://www.lumes.lu.se George, J.M. and Jones, G.R. (2008). Understanding and managing organizational behavior. Pearson International Edition. Building Green, S.D. and May, S. (2005). Research and Information, 33(6). Harris, F. and McCaffer, R. (1997). Modern Construction Management. London: Blackwell Science. Howell, G.A. (1999). What is Lean Construction?. Proceeding Seventh Annual Conference Of International Group Of Lean Construction, IGLC-7, University Of California, Berkeley, CA, USA. Jorgensen, B., and Emmitt, S. (2008). Lost in Transition: The Transfer of Lean Manufacturing to Construction Engineering. Construction and Architectural Management, 15(4), 383-398. Kim, D., and Park, H-S. (2006). Innovative Construction Management Method: Assessment of Lean Construction Implementation. KSCE Journal of Civil Engineering,10(6), 381-388. Koskela, L. (1992) Application of the new production philosophy to construction. Tech. Report No. 72. CIFE, Stanford University, CA.

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Lean Construction Institute. (2012). What is lean construction?. Retrieved 13 February 2013 from http://www.leanconstruction.org Lean Enterprise Institute. (2009). Principles of lean Lim, V.L.J. (2008). Lean construction: knowledge and barriers in implementing into Malaysia construction industry. Retrieved 26 August 2011 from http://eprints.utm.my theoretic perspective . Journal of Operations Linderman, K., Schroeder, R.G., Zaheer, S., & Choo, A.S. (2003). Management, Elsavier Science, 21, 193-203. Lukowski, J. (2010). Lean construction principles eliminate waste. Retrieved 25 August 2012 from http://www.powermag.com Marhani, M.A., Jaapar, A. and Ahmad Bari, N.A. (2012). Lean construction: Towards Enhancing Sustainable Construction in Malaysia Conference. Proceeding at Asia/Pacific International Conference on Environment-Behaviour Studies, Cairo, Egypt. (SCOPUS) 31 October 2012-2 November 2012 Ministry of Finance. (2012). The 2010 Budget Speech. Retrieved 3 October 2012 from http://www.treasury.gov.my/pdf/budget/bs10.pdf Mitsuishi, M., Ueda, K. and Kimura, F. (2008). Manufacturing Systems and Technologies for the New Frontier. The 41st CIRP Conference on Manufacturing Systems. May 26-28, 2008, Tokyo, Japan. Mohd Nasir, H., Yusoff, M.K., Sulaiman, W.N.A. and Rakmi, A.R. (1998). Issues and problems of solid waste management in Malaysia. Proceedings on national review on environmental quality management in Malaysia: towards the nest two decades, 179 225. Mohd Yunus, N.M. (2006). Implementation of OHSAS 18001:1999: The experienced of construction companies in Malaysia. Universiti Teknologi MARA Shah Alam, Malaysia. . Retrieved 25 December 2012 from Mossman, A. (2009). http://www.leanconstruction journal.org -to-gem . Proceedings: IGLC-16, 14Olatunji, J. (2008). L 20 July, Manchester, UK. Seppanen, O., Ballard, G. and Pesonen, S. (2010). The combination of last planner system and location based management system. Retrieved 15 October 2012 from http://www.lean.org Pepper, M.P.J and Spedding, T.A. (2010). The evolution of Lean Six Sigma . International Journal of Quality & Reliability Management, 27 (2), 138-155. Puvanasvaran, A.P., Kerk, R.S.T. and Muhamad, M.R. (2011). Principles and Business Improvement Initiatives of Lean Relates to Environmental Management System. Retrieved 25 August 2012 from http://ieeexplore.ieee.org. RIBA. (2012). RIBA Plan of Work. Retrieved 15 October 2012 from http://www.pedr.co.uk. Salem, O., Solomon, J., Genaidy, A., and Minkarah, I. (2006). Lean construction: From theory to implementation. J. Manage. Eng., 22(4), 168-175. Salem, O., Solomon, J., Genaidy, A. and Luegring, M. (2005). Site implementation and assessment of lean construction techniques. Lean Construction Journal, 2, October 2005: pg. 1-21. Shafii, F., Arman Ali, Z. and Othman, M.Z. (2006). Achieving sustainable construction in the developing countries of Southeast. Asia Proceedings of the 6th Asia-Pacific Structural Engineering and Construction Conference (APSEC 2006), 5 6 September 2006, Kuala Lumpur, Malaysia. Small, H.M., and Yasin, M.M. (2011). Assessing the implementation and effectiveness of process management initiatives at technologically consistent firms Business Process Management, 6-20. Summers, D.C. (2005). Quality Management, Creating and Sustaining Organizational Effectiveness Upper Saddle River, New Jersey: PEARSON Prentice Hall. Suresh, S., M. Bashir, A. and Olomolaiye, P.O. (2011). A protocol for lean construction in developing countries. SPON Press. New York. Tindiwensi, D. (2006). An Investigation into the Performance of theUganda Construction Industry. PhD Thesis. Makerere University: Uganda. The Star Online (2009). Budget 2010: 1Malaysia, together we prosper. Retrieved 25 August 2012 from http://thestar.com.my WCED (World Commission on Environment and Development) (1987) Our common future Oxford University Press, Oxford Womack, James P., Jones, and Daniel, T. (1996) Lean Thinking. Simon and Schuster. New York. pp 350. Yahya, M.A. and Mohamad, M.I. (2011). Review on lean principles for rapid construction. Jurnal Teknologi, 54 (Sains Kejuruteraan) , 1-11.

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SUSTAINABLE CONSTRUCTION: IS LEAN GREEN? Ritu Ahuja Assistant Professor, Amity School of Architecture and Planning, Amity University, Noida – 201301, Uttar Pradesh, India; Ph (0091) 8506051102; email: [email protected], [email protected] ABSTRACT The paper aims to study the novel concept of ‘Lean Construction’ in the world. Another intention is to examine how current Lean construction tools and methods impact the construction and operation of sustainable facilities. The Lean and green Construction philosophy can tremendously improve the needs and result in high productivity of the construction industry. The paper also finds out how these Lean construction tools and methods have evolved to contribute to green construction. In order to achieve the project aim, there are four main objectives: 1. To investigate the concept of lean and its application to the construction industry. 2. To define sustainability and identify its application to the construction industry. 3. To establish a link between the lean and sustainability. The Lean principles emphasise on eliminating process and material wastes and which can further result to the green construction which emphasise on the energy efficiency and the cost efficiency. Keywords: Lean Construction, green, Sustainable construction, sustainability INTRODUCTION The major concern today relates to the 4 R’s i.e. Reduce, Recycle, Reuse and Regulate. In the recent years, eliminating the ‘concept of waste’ and creating a healthier environment through design and management has become a prime goal, thus involving the issues of sustainability in construction. Today, the construction industry is facing a number of problems which include cost overrun, completion delay, low productivity, poor quality. These inherent problems need to be solved and taken care of in order to bring an overall change and improvement in the current scenario of the construction industries. The need for the change can only be resolved by the Lean construction and Lean project management approach. The construction industry lags 10 years behind the manufacturing industry because of the several reasons. The primary reason being its fragmented approach rather than an integrated approach. The second important reason is that the construction industry is far more complex than the manufacturing and thus the technical innovations are required to be more developed to be significantly implemented. Lean construction is a new production philosophy which would bring in revolutionary changes in the construction industry.

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Lean production focuses on eliminating waste and maximizing productivity through the pull system, employee involvement, continuous improvement, etc. Much has been discussed about the waste elimination and productivity improvement that can be achieved by applying the lean concept. However, as the consideration of the environment is becoming an increasingly important part of the construction culture, there is a need to investigate the applicability of the lean concept to achieve environmental sustainability, which is often used interchangeably with the term “green”. LEAN APPROACH To bring the construction industry at a competitive base, Lean Project management approach is to be adopted. According to Koskela (1994), the principles, techniques and tools which are related to the processes of lean production and their management can be usefully employed by the construction industry. Lean philosophy is all about designing and operating the right resources at the right time with right systems. The most essential and important objective of lean philosophy is to identify, eliminate waste and achieving the customer needs in all respects. Two very important construction tools are added under lean construction are the production control and structuring of the work. According to the Lean construction Institute, LCI, lean construction is a production management based approach to project delivery. It is a new way to design and build capital facilities. Lean construction has successfully resulted into maximising the value and minimising the waste in the construction process. Lean significantly contributes to the efficiency of the construction industry. The application of lean in the construction process has resulted into structuring of the work throughout the process and the improvement of performance of the project. Lean construction assures to deliver reliable work between specialists in design, supply and assembly, thus delivering Value to the customers and reducing the waste. SUSTAINABLE CONSTRUCTION- GREEN CONSTRUCTIONDEFINITION AND NEED As the world is becoming increasingly concerned about the environment and surrounding, there is a tremendous focus on all the industries including the construction industry to adopt the proactive approach to green construction. Sustainability in construction will not only benefit individuals but also contribute to the global issues. Sustainability in construction can only be achieved by rethinking operation in four major areas, i.e., Energy, Materials, Waste and Pollution. Implementation of changes to achieve sustainability will vary from firm to firm. It will be different for the larger firms from small and medium sized firms The figure 1 shows the evolution and challenges of the sustainable construction concept in a global context.

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Figure 1. Challenges of sustainable construction in a global context Green construction refers to the planning and management of a project that result into minimising the impact of construction process on the environment. The impact of the construction process on the environment can be reduced in the following ways: 1. By enhancing and improving the efficiency of the process. 2. By conservation of water, energy and other resources during the construction process. 3. By reducing the amount of waste during the construction process and minimising other activities that might lead to reduce the costs and maximise the productivity of a project. WASTES IN CONSTRUCTION INDUSTRY Reduction and removal of waste is an important part of lean and green construction. Using the material resources efficiently can lead to sustainable waste management. Waste is hardly ever recognised by the project managers which is the major cause of loss of efficiency and productivity (Koskela 1992). Figure 2 identifies the seven forms of waste which are over production, conveyance, inventory, processing, waiting, correction and motion.

Figure 2. Forms of Waste

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We can reduce the level of waste production in the construction industry by designing such a way that minimum waste is generated, by increasing the efficiency of the production process, by using the just-in- time tool to prevent the wastage of unused material, by recycling materials wherever possible and by educating the staff about waste reduction and material recycling.   THE PRACTICAL RELATIONSHIP BETWEEN LEAN METHODS AND SUSTAINABLE IMPACTS- THE LEAN DELIVERY PHASESThe Lean Project Delivery system consists of four interconnecting phases extending from Project definition to Design, supply and assembly. (Figure 3) The Project Definition consists of three different modules: Needs and Value Determination, Design Criteria and Conceptual design. Defining value and waste is critical in Lean production. Value management aims to maximize value and eliminate waste. Minimal building impact, maximum building system efficiency, energy efficiency, waste reduction, and a healthy, productive environment for occupants are the key features of the lean and green construction. The social impact of facilities has been one of the critical concerns in the architecture industry. It is hard to measure the social impacts of facilities on humans and communities. Lean construction needs to identify sustainable values including economic, environmental and social values as important factors in implementing sustainable construction. Lean Design is a process that includes various construction techniques and materials to produce value to an owner. This process is very important considering the impacts to the overall life of a facility. The green facilities can only be applied to its best in a design contributing to sustainable construction only if the use of green materials, resources and the construction technologies is comprehensively coordinated with each other.

Figure 3. The Lean Project Delivery System

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In order to minimize environmental impacts and energy consumption during construction of sustainable facilities, several Lean design methods could be implemented: Integrated Design (Whole system design), Design for Maintainability (DFM), Set-based Design, Target Costing, and 3D Modeling. Lean Supply: Just-in-time (JIT) could also be regarded either as an environmentally-friendly method or the opposite. Just-in-time reduces damage and materials (Riley et al., 2005). Moreover, this method may reduce the various sources of extra inventory but at the same time, however, the frequent transportation of inventory and materials may cause volatile organic compounds and CO2 emissions. Even though applications in the manufacturing industry and construction industry are not exactly the same, we need to notice the probabilities and possibilities of bad environmental impacts from Lean adaptation. The consideration from the holistic perspective is required to increase the sustainability of a construction project. Lean Assembly: One of the most successful procurement methods that can be adopted to achieve sustainability is the Prefabrication. Economic, social, and environmental indicators from (Horman et al, 2005) examined the impacts of prefabrication for purposes of sustainability using these indicators (Horman et al., 2005 in Luo et al., 2005). The features of prefabrication on sustainable constructions include: •

Increased potential of improved supply chain integration of green materials

•

Safer working conditions.

• • • •

Reduced environmental impact due to transferring workers, machines, staked materials, temporary structures and onsite activities to a prefabrication plant Easier recycling of materials in an off-site environment Enhanced flexibility and adaptability Reduced overall life cycle cost

•

Reduced economic impact in local communities.

Prefabrication may have both sustainable benefits and disadvantages depending on the exact conditions of a project. These impacts fall into three categories: economic, social, and environmental. Thus, economically, one advantage is the reduced cost of prefabricated units as opposed to on-site units. Socially the working conditions are safer and more stable in prefabricated construction than they are on-site. Environmentally, this method may improve the supply chain for green materials, one aspect of green facilities. Yet, there are some problems as well. Economically, and socially, less local labour is needed, thus the salaries of the workers do not contribute to the local economy. Environmentally, this process may consume more energy for transportation of prefabricated products and emit more air pollution.

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Kaizen, which means continuous improvement in Japanese, is a core component of Lean production not only for economic purposes, but also for social and environmental purposes in sustainable construction. Kaizen plays a key role in improving the current status for sustainable construction. All sustainable indicators may be improved through Kaizen. Another potential tool for sustainable perfection is Kaikaku. Kaikaku (Kaizen events), means a rapid process of improvement, is a team activity designed to eliminate waste and make rapid changes for product and process improvement in the workplace. This strategy is employed to get workers with multiple organizational functions on different levels to unite in improving processes and addressing problems. When implementing chosen improvements, the team rapidly employs inexpensive solutions usually within three days. Kaikaku can create reduced pollution and material waste.

Figure 4. Lean Methods and Sustainable Impacts Figure 4 illustrates a quantitative assessment of the previously discussed methods on the sustainability of a construction project. Most lean construction methods provide positive economic impacts for sustainable facilities while showing several no-impacts or negative impacts on social and environmental aspects. The table shows concrete relationships between the Lean construction methods and the sustainable construction of a facility, while several Lean construction practices reveal no relationship or negative relationships. The Lean principles emphasise on eliminating process and material wastes and which can further result to the green construction which emphasise on the energy efficiency and the cost efficiency. The Lean and green Construction philosophy can tremendously improve the needs and result in high productivity of the construction industry. The lean and green theories both complement each other. The green construction in addition to the theories of lean construction also focuses on the recycling, reusing of the resources thus making the process and the project cost efficient and most productive.

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Figure 5. Relationship between sustainable development and Lean production In the figure 5, the four interconnecting phases of the Lean Project Delivery System (LPDS) extending from project definition to design, supply, and assembly are used to illustrate the Lean construction process (Ballard, 2000). Addressing sustainable issues, such as economic, social, and environmental values as the requirements of an owner, Lean may act from the project definition to the construction phase for a sustainable facility. CONCLUSION AND RECOMMENDATION The research tries to bring out the need for the implementation of lean philosophy in the construction industry. Lean Construction should be adapted and considered as it can solve many problems of the construction industry and the project management as the cost over run, poor quality and the delays. It has been insisted that the Lean philosophies offer the conceptual basis, and lean construction methods and tools have great possibilities for sustainable construction (Huovila and Koskela, 1998).The sustainability in a project can be achieved by following the lean principles. The lean philosophy not only provides the economic value to the process, but, can also provide the social and environmental value. This can be achieved by following and improving the green project management facilities. The lean and green philosophies together can give help the construction industry more efficient. To make a project lean and green, the research brings out the three key impacts of lean construction methods to achieve sustainability: 1. Economic value in a project can be achieved by reduction of cost, saving of resources, by minimising the operation cost and maximising the productivity of the process. 2. Social Value can be achieved by making the workplace safe, by being loyal among the team members and the stakeholders, by keeping in mind the community welfare and happiness. 3. Environmental Value can be achieved by minimizing the resource depletion, by saving and preserving the resources and by the removal of waste thus, preventing the environment from pollution. The importance of environmental aspects cannot be separated from the lean construction as they add value to each other when combined and used correctly. The

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methods of lean construction should be extended to environmental planning to help improving the efficiency of the production management process. In this paper, most of the lean construction methods and the green construction methods are studied and examined. Although there are many other lean construction methods which are not been examined for sustainability, but if studied in future, will surely have a possibility for sustainable purpose. REFERENCES Ballard G., Howell G. (1994), “Implementing lean construction: Improving downstream performance”. Ballard G., Howell G. (1998), “Implementing lean construction: Understanding and Action”, Presented at the Annual Conf. International Group for Lean Construction. Ballard, G. (2000). “Lean project delivery system.” Lean Construction Institute White Paper No. 8, Lean Construction Institute, Ketchum, Id. Ballard G & Howell AG. (2003) Lean Project Management. Building Research and Information, 31(2), 119-113 Bourdeau, L., Huovila, P., Lanting, R., and Gilham, A. (1998), “Sustainable Development and the Future of Construction- A comparison of visions from various countries” . CIB Report 225, Rotterdam. Charles J. Kibert (2008), Sustainable Construction, Green building Design and Delivery, second edition. Cusumano, M.A. (1994). “The Limits of ‘Lean’,” Sloan Management Review, vol. 35, no. 4, Summer; pp. 27-32. Degani, C.M. and Cardoso, F.F. (2002). “Environmental Performance and Lean Construction Concepts: Can We Talk about A 'Clean Construction'?” Proceedings IGLC-10, Gramado, Brazil Green S. D; “The Future of Lean Construction: A Brave New World”, International Conference on Lean Construction; Brighton; 2000. (Conference proceedings) Helper, S. and Clifford, P. (1997). “Can Green Be Lean?” paper presented to the Academy of Management meetings, Boston, MA Horman, M.J., Riley, D., Pulaski, M.H., and Leyenberger, C. (2004). "Lean and Green: Integrating Sustainability and Lean Construction." CIB World Building Congress, Toronto, Canada. Howell G.A.(1999), “ What is Lean Construction-1999” 26-28 July 1999, University of California, Berkeley, CA, USA Huovila, P. and Koskela, L. (1998). “Contribution of the Principles of Lean Construction to Meet the Challenges of Sustainable Development” Proceedings IGLC-6 Guaruja, Brazil

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THE INTEGRATION OF LEAN MANAGEMENT AND SUSTAINABILITY Ing. Ľubica Kováčová Technical University of Kosice Faculty of Mechanical Engineering Department of Materials and Technology Masiarska 74, Košice [email protected] Abstract Lean Production is defined as a business system for organizing and managing product development, operations, suppliers, and customer relations that requires less human effort, less space, less capital, less material, and less time to make products with fewer defects to precise customer desires, compared with the previous system of mass production. Sustainable manufacturing is defined as the creation of manufactured products that use processes that are non-polluting, conserve energy and natural resources, and are economically sound and safe for employees, communities, and consumers. Article discusses the similarities and differences between lean and sustainability. It analyses the gradual extension of the lean direction to sustainability. Key words: Lean Manufacturing, Sustainability INTRODUCTION Lean management is now widely used especially in the automotive industry. Further development of lean principles is associated with sustainable development. This article addresses the issues of integration of lean and sustainability. Lean Production is defined as a business system for organizing and managing product development, operations, suppliers, and customer relations that requires less human effort, less space, less capital, less material, and less time to make products with fewer defects to precise customer desires, compared with the previous system of mass production. The goal of Lean Manufacturing is described as "to get the right things to the right place at the right time, the first time, while minimizing waste and being open to change". The principles of Lean Manufacturing enabled the company to deliver on demand, minimize inventory, maximize the use of multi-skilled employees, flatten the management structure, and focus resources where they were needed. The ten rules of Lean manufacturing management can be summarized [2]: 1. Eliminate waste 2. Minimize inventory 3. Maximize flow

4. Pull production from customer demand 5. Meet customer requirements 6. Do it right the first time 7. Empower workers 8. Design for rapid changeover 9. Partner with suppliers 10. Create a culture of continuous improvement Sustainable manufacturing is defined as the creation of manufactured products that use processes that are non-polluting, conserve energy and natural resources, and are economically sound and safe for employees, communities, and consumers.” Sustainable manufacturing includes the manufacturing of “sustainable” products and the sustainable manufacturing of all products. The former includes manufacturing of renewable energy, energy efficiency, green building, and other “green” & social equity-related products. [3] Green, or sustainable, manufacturing is defined as a method to “develop technologies to transform materials without emission of greenhouse gases, use of non-renewable or toxic materials or generation of waste”. The term “green“ often used interchangeably with “environmentally-safe”. [5]: The viewpoint of sustainability is the opposite of financial short-term thinking. Like lean, it stresses closed-loop, cyclical thinking rather than linear, goal-oriented thinking. It actually goes even farther, into whole-system thinking, which causes practitioners to look for long-term unintended consequences of their decisions. Sustainability assumes that resources are finite, and therefore that resources should be re-used, and reused again. SIMILARITY AND DIFFERENCES BETWEEN LEAN AND SUSTAINABILITY Sustainability can be thought of as lean extended to a much broader objective. A company familiar with lean will easily grasp sustainability. Lean works when individuals and teams throughout an organization start asking questions such as "How does this add value to the customer?" and, "How can we do this better?" Sustainability works the same way —the only difference is the decision-making criteria. Rather than focusing on the economic customer, sustainability focuses on three bottom lines — profitability, people, and the planet. It focuses on the longer term, on life.

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Transfer inovácií 26/2013 2013 –––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––– Table 1: Lean and Sustainability are Connected [3]: LEAN Long term philosophy- create value for people, community/ including environment/, economy Create the right process to produce the right result Add value by developing people and partners Continuously making problems visible a solving root causes drivers organizational learning Minimize or eliminate waste of any kind

SUSTAINABILITY Invest in long term- consider people, community, financials, environment Ensure the ecosystem is in balance, if necessary, intervene in system Invest in people- consider stockholders including your staff and partners/e.r. suppliers/ Be transparent and consider the whole system vs. treating symptoms Creating waste harms something else in the system

For a company that has started on its lean Since one main objective of sustainability journey, moving toward sustainability is relatively is to live within nature's income, use of key easy. Many lean tools are easily adapted and resources, such as materials and energy, must be extended for sustainability, as illustrated by the monitored as processes are improved or redesigned. following examples. Besides the metrics that usually guide lean operations, a few others are often associated with Value Stream Mapping: Widely used in lean sustainability. thinking to see a whole picture and decide where to focus improvement efforts, it readily extends to Examples of environmental metrics: sustainability, especially to the environmental side.  Energy used per unit of output Just add appropriate metrics, such as hazardous  Percent of energy from renewable resources material used/generated, water used, and energy used.  Yield: Mass of finished goods per mass of raw material consumed Work Teams: Just as in lean, work teams are the heart of sustainability — they do most of the  Percent of raw materials reused or from thinking, the data gathering, the analysis, the idea recycled sources generating, and the implementing. And work teams,  Emissions, especially greenhouse gas by their very nature, implement the social side of emissions, both total and per unit of output sustainability.  Effluents discharged per unit of output 5S: For sustainability, some companies add a sixth S, Safety, and seventh S, Sustainability. The green wastes are very different from Analysis Tools: Teams focusing on sustainability the lean wastes. Lean seeks to eliminate traditional can incorporate traditional lean analytical tools, production objectives like cost or time while green such as Pareto charts, Ishikawa diagrams, and the is concerned with wastes that impact the "5 why's" into their analyses. For example, environment as seen in Table 2 hazardous material and releases of toxic substances can be analysed as if they were process defects. Additional Tools for Sustainability Table 2: Waste identification in green manufacturing [1]: Concept Description Permit Compliance Compliance with applicable permits. Toxic Release Inventory (TRI) Over 300 chemicals subject to release. 33/50 Chemicals A subset of chemicals identified by the EPA as priority candidates for voluntary reductions by industry. Clean Air Act Toxics 189 chemicals listed in the Clean Air Act as air toxics. Risk-Weighted Releases Toxic chemicals weighted by their relative toxicity. Waste Per Unit of Production Percentage of production lost as waste, generally measured by weight. Energy Use Total energy use by all aspects of corporate operations; also expressed as carbon dioxide. Solid Waste Generations Total solid waste going to landfills or other disposal facilities. Product Life Cycle The total impact of a product on the environment from raw materials sourcing to ultimate disposal.

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Transfer inovácií 26/2013 2013 –––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––– FROM LEAN TO GREEN MANUFACTURING The leading similarity between the benefits of lean and the benefits of green is waste, and so it makes perfect sense that in order to achieve higher levels of environmental performance, your organization must first adopt the principles and practices of lean manufacturing. Other lean concepts such as operator care; Kanban and SMED can potentially improve the environmental performance of your organization as well. Operator care programs focused on developing standards of practice within the operating units decrease variation in the manufacturing process, which reduces the amount of product and raw materials waste. Kanban, or pull-systems established within the manufacturing process, have greatly contributed to material and waste reductions. Kanban practices are designed to provide the right materials at the right time to support manufacturing needs. This concept focuses on reducing excess inventories of raw or work-in-process materials, which cannot be consumed immediately by the production cycle. Cell-based manufacturing processes that signal a pull for materials based on the demand for product can significantly reduce raw material consumption, decreasing the amount of waste material delivered to landfills as well as reducing the demand on raw material resources. SMED, or single minute exchange of dies (a practice that helps your organization reduce changeover durations in order to adjust the manufacturing process based on product demand) has the potential to reduce the amount of waste generated from raw and unprocessed materials left over in the manufacturing processes. Tools for eco- efficiently Organizational/Management Environmental Management Systems Stakeholder Engagement Corporate Environmental Reporting Life-Cycle Management Product Design & Development Design for Environment Eco-Efficiency Analysis Life-Cycle Assessment Of end-of-life system Environmental Risk Assessment Integrated Product Policy (IPP) Suppliers/Purchasing Environmental Supply Chain Management Green Procurement Marketing and Communications Corporate Environmental Reporting

Eco-Labelling Stakeholder Engagement Production & Distribution Eco-Efficiency Analysis Industrial Ecology Pollution Prevention Life-Cycle Costing Facilities Management/Project Development Green Building Design Environmental Impact Assessment Environmental Management Systems Stakeholder Engagement Life Cycle Assessment-LCA A decision-making tool to identify environmental burdens and evaluate the environmental consequences of a product, process or service over its life-cycle from cradle to grave standardized by the International Organization for Standardization forms the conceptual basis for a number of management approaches that consider a product across its life-cycle, covering resource acquisition, product manufacturing, product use, and end-of-life LCA – key elements: 

Consideration of multiple life cycle stages.



The physical sequence of operations in a product system, cradle-to-cradle or earthto-earth.



The primary stages are materials acquisition and processing, manufacturing, use and end-of-life disposal within each of these stages; sub stages or unit processes are defined.



Consideration of multiple environment and resource issues.

LCA studies expose trade-offs by analysing significant inputs from the earth and outputs to the environment across the various lifecycle states. An assessment or interpretation of the significance of the results can vary from aggregation of data into a set of simple indicators to the consolidation of the data into a core set of indicators using a variety of weighting or scoring methods. LCA can help decision-makers to:  Identify unintentional impacts of actions (e.g. upstream GHG emissions that may offset perceived benefits of a new technology).  Ensure consideration of all environmental media across the life-cycle (e.g. equal consideration of emissions to air, water and land during project construction, operation and decommissioning).  Avoid shifting problems from one life-cycle stage to another, from one geographic area to another and from one environmental medium to

197

Transfer inovácií 26/2013 2013 –––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––– another (e.g. ensuring an air pollution mitigation measure does not create a water pollution problem elsewhere in the system).  Identify opportunities to improve the environmental and economic performance of the technology, project, product or service in question (e.g. identifying “hotspots” that need to be addressed).  Communicate more effectively with stakeholders on the system wide consequences of project or technology options (e.g. to communicate full impacts and/or benefits of changes to a product system). Design for Environment (DfE) or Ecodesign The integration of environmental considerations into product and process design. Fundamental to DfE is the use of tools and practices that encourage environmental responsibility and simultaneously reduce costs promote competitiveness and enhance innovation. DfE practices are meant to develop more environmentally compatible products and processes while maintaining (and in some cases even exceeding) price, performance and quality standard. Key elements of DfE are: 

Selection of low-impact materials.



Reduction of energy use.



Optimisation of production techniques.



Optimisation of distribution system.



Reduction of use phase impacts.



Optimisation of initial lifetime.



Optimisation.

Apply DfE/eco-design is important: 

At the front end of the product development process (e.g. at the planning and conceptual design phase).



Often the design strategies are informed by prior analytical work on the life cycle cost and environmental impacts of the previous generation of products.



In innovation processes DfE may be used to inform product design (e.g. material selection) through the use of design checklists.

Cleaner production/pollution prevention. The continuous application of an integrated preventive environmental strategy applied to processes, products and services to increase eco-efficiency and reduce risk for humans and the environment. For processes, cleaner production includes conserving raw materials and energy, eliminating toxic raw materials and reducing the quantity and toxicity of all emissions

198

and wastes before they leave a process. For products, the strategy focuses on reducing impacts along the entire life cycle of the product, from raw material extraction to the ultimate disposal of the product. Cleaner production – key elements Cleaner production is a broad term encompassing the following concepts: 

Waste minimization and avoidance



Pollution should be prevented or reduced at the source whenever feasible



Environmental management, Substitutions for toxic and hazardous materials



Process and product modifications



Internal reuse of waste products

Environmental Management System (EMS) The organizational structure, responsibilities, practices, procedures, processes and resources for implementing and managing an organization’s environmental affairs while ensuring conformity to its policies, standards and stakeholders’ expectations. EMS – key elements: 

Purpose – an organization should have an identifiable purpose, which is usually stated as its goals and objectives and encapsulated in the organization’s environmental policy, Commitment – there should be a sense of commitment and accountability among the people in the organization with respect to taking the appropriate action in support of the EMS.



Capability – the organization should have the necessary resources (human, physical and financial) as well as the knowledge and skills to achieve the organization’s environmental policy. Learning – the organization should strive to continuously learn to improve its own management and learning processes through monitoring and measurement of environmental performance, efficient internal and external communication as well as review of the EMS by senior management.

While there has been an increased awareness of EMS due to the creation of the international standard on EMS (ISO 14001) it is important to understand there are a variety of EMS’s in use by industry such as Responsible Care in the chemical industry, the EU standard EMAS and others. References [1] A case study of lean, sustainable manufacturing - Journal of. Industrial Engineering and Management. Geoff Miller, Janice Pawloski, Charles Standridge, JIEM, 2010 – 3(1): 11-32 – Online ISSN: 2013-

Transfer inovácií 26/2013 2013 –––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––– 0953www.jiem.org/index.php/jiem/article/downloa d/156/50 [2] Learning unit C: implementing eco-efficiency, 38 The California State University: http://www.pdx.edu/fadm/sites/www.pdx.edu.fadm/ files/ [3] National Counsil for Advanced Manufacturing http://www.nacfam.org/PolicyInitiatives/Sustainabl eManufacturing/tabid/64/Default.aspx

[4] Langewalter, G. Life is Our Ultimate Customer: From Lean to Sustainability, http://www.zerowaste.org/publications/Lean_to_Su stainability.pdf Acknowledgments This contribution is the result of the international project implementation: Hungary Slovak Republic LEAN LAB HUSK/1101/1.6.1 supported by EU founds

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Jestr

JOURNAL OF

Journal of Engineering Science and Technology Review 10 (4) (2017) 170- 177

Review Article

Engineering Science and Technology Review www.jestr.org

The Practical Relationships between Lean Construction Tools and Sustainable Development: A literature review M. S. Bajjou*, A. Chafi, A. Ennadi and M. El Hammoumi Science and Techniques, Sidi Mohammed Ben Abdellah University, B.P. 2202 - Route d’Imouzzer – FES, Morocco Received 16 February 2017; Accepted 14 September 2017

___________________________________________________________________________________________ Abstract The construction industry is considered among the largest consumers of natural resources (non-renewable materials, fossil fuels, water...). It is also an important source of generation of solid waste and greenhouse gas emissions. In addition to its negative impacts on the environment, most construction projects are characterized by the non-respect of the triptych (Cost, Time, Quality) and a high accident rate compared to other sectors. Lean construction (LC) is a new production philosophy which has the potential of bringing innovative improvements in the construction sector. It is a systemic approach to meeting customer expectations by maximizing added value and reducing all forms of waste. Based on international standards (AFNOR, GRI, UNEP, ISO 26000...) and recent researches published in the most reliable databases, this study aims at exploring the concept of sustainable development in the context of the construction industry and examines how the LC tools (Prefabrication, Value Stream Mapping, Poka-Yoke, visual Management, and 5S) can have an impact on the three dimensions of sustainable development (environment, economy, society). This work brings a new reflection by constructing an interaction matrix between the Lean Construction tools and sustainable development. Keywords: Lean Construction, Sustainable development, Interaction matrix

____________________________________________________________________________________________ 1. Introduction The sector of construction represents an integral part contributing tangibly to the economic growth of developing countries. At the national level, the sector of construction is considered amongst the most dynamic and the most promising of the Moroccan economy, it contributed by 6.3% of total value added created in 2014 with an increase of 4% compared to 2013 [1]. It employs nearly a million people (9,3% of the active population) [2]. On the other hand, even if the construction industry participates in strengthening the national economy and reducing the unemployment rate, this sector also has a huge impact on the environment compared with other industries, and it is considered within the most polluting sectors [3, 4]. The construction industry is a very large consumer of non-renewable resources. Similarly to its damaging effects, it is also an important source of natural resources waste (non-renewable materials, water...), solid waste generation and greenhouse gas emissions. In Morocco, almost 9 million tons of solid waste are dumped every year in nature [5]. Besides that, the Moroccan construction industry is considered as the largest consumer of energy; it accounts 36% of final energy consumption and 32% for the manufacturing sector [6]. Moreover, it is considered among the sectors of activities having a great impact on air pollution and the deterioration of the ozone ______________ *E-mail address: [email protected] ISSN: 1791-2377 © 2017 Eastern Macedonia and Thrace Institute of Technology. All rights reserved.

doi:10.25103/jestr.104.20

layer; it is a source of 45 million ton of CO2 (in 20 years, CO2 emissions have increased by more than 200 %) [7]. In addition to its negative impacts on the environment, most construction projects are characterized by high variability and high accident rate compared to other sectors [8]. According to the last studies carried out by Lean Construction Institute (LCI) [9], the sector of construction is characterized by a ratio production/waste higher than that of the manufacturing sector as could be seen in Fig. 1.

Fig. 1. Comparison of Production\/waste ratios between manufacturing sector and construction sector

It has become crucial to seek creative and innovative solutions that ensure better and more optimized modes of management. Because of its great potential in achieving customer expectations in terms of increasing the value and reducing all forms of waste, the Lean Construction philosophy is considered an alternative approach which can bring revolutionary changes to the construction industry. The LC is a concept that derives from the manufacturing industry, adopted in the industry of construction with its objectives to minimize waste and maximize the value added

M. S. Bajjou, A. Chafi, A. Ennadi, and M. El Hammoumi/Journal of Engineering Science and Technology Review 10 (4) (2017) 170-177

in construction projects. LC is a proven method for the management and optimization of the construction process, hence the requirements of customers can be reached using good resources and as well its ability to provide the best quality from the first time. Various lean tools for achieving sustainable development have been discussed by several authors. However, in the literature, there are only a very few studies that have explored various issues of sustainability by means of lean construction initiatives and established the benefits that can be derived by applying the lean tools. The purpose of this study is to analyze the concept of sustainability in the context of the construction industry based on a literature review of scientific contributions published in reliable journals. This work brings a new reflection focusing on the relationship between lean construction tools and the three challenges of sustainable development (environment, economy, society).

Economy

Cost saving

1

Increase added value5 Time reduction1 Partnering3 Competitiveness2 Waste Reduction1 Measure customer satisfaction5 Responsiveness3 Flexibility2 Increase workers productivity1 Material and resources6 Energy efficiency6

[3, 4, 14, 15] [3, 4, 11, 14, 15, 16] [3, 11, 13, 14] [3, 11, 14, 15] [3, 13] [6, 11] [3, 11, 13, 14, 17] [11,15, 16] [15, 18] [4, 14, 15] [11, 15] [3, 4, 16, 18, 19, 20] [3, 4, 16, 18, 19, 20] [3, 4, 16, 18, 19, 20] [3, 4, 19, 18, 20] [3, 16, 20] [16, 18, 20] [4, 16]

Emission of greenhouse gases8 Water efficiency6 Environment Solid wastes9 Resource depletion6 Pollution Prevention7 Production of toxic [3, 4, 16, 21] products7 9 Solid waste treatment [19, 22] Use of land6 [3, 4, 18] Working conditions10 [3, 4, 16] Health and safety (e.g. employees injuries, [3, 11, 16] fatalities) 10 Labor/Management [3, 11, 16] Society Relations10 11 Employment contribution [3, 4, 16] Education/training11 [3, 4, 16] human resource [3, 16] development11 12 Employment [3, 4, 12, 16, 23]

2. The concept of sustainable development 2.1 Sustainable construction Sustainable construction is mainly defined by the industry that ensures the conservation of natural resources throughout the life cycle of the building (energy, water, non-renewable materials), optimizing the consumption of raw materials in purpose to reduce the deterioration of the environment and to ensure social and economic comfort [10]. A sustainable and ecological construction project must necessarily take into account the objectives of sustainable development at every stage of decisions: design, construction, use, and demolition. In addition to these earnings to the level of socioeconomic development and the protection of the environment sustainable construction practices ensure other intangible benefits such as strengthening the company's name in the market, the resistance to global competition, improving the quality of infrastructure and creation of working conditions guaranteeing motivation and employee satisfaction [11].

The analysis of the data in Tab. 1 has allowed us to identify twelve main factors, as shown in Fig. 2, spread over the three dimensions of sustainable development (Economy, Environment, and Society). These main factors encompass the thirty factors that were found in the literature and international standards. They are identified in Tab. 1 by the exhibitors ranging from 1 to 12 depending on the correspond issue. These main factors will be used in the development of a matrix of interaction between LC tools and the three dimensions of sustainable development.

2.2 The main factors of sustainable development There are several definitions of sustainable development in the literature, especially that sustainable development is a broad concept that has been adopted and interpreted in many contexts. The most popular definition of sustainable development is that given in the Brundtland report [12]: “Development that meets the needs of the present without compromising that ability of future generations to meet their own needs”

3.1 Origin The study carried out by Pappas [24] in 1990 noted that only 11.4% of the time on construction site created addedvalue. Other Swedish studies in their turn, have observed that the operations which create added value represent only 30% of time spent on a construction site [25, 26]. LC is a new philosophy of production, representing the adaptation of the concept Lean manufacturing with the peculiarities of the construction industry. Due to its great potential in fulfilling objectives in term of increasing the added value and productivity LC has gradually interested stakeholders of the construction industry. The discussions relative with the concept of LC began in 1992 when Koskela thought of introducing Lean philosophy

In order to assess the impact and contribution of the lean construction philosophy in sustainable development, we have clarified the key factors of the three dimensions (economy, environment, and society) based on international standards (AFNOR, GRI, UNEP, ISO 26000...) and on recent research published in the most reliable international journals. The most common factors of sustainable development are shown in Tab. 1. Table 1. The factors of sustainable development Dimensions factors References Productivity/profitability1 [3, 4, 13, 14, 15] Quality1 [3, 4, 11, 15, 16]



Innovation/R&D4

171

M. S. Bajjou, A. Chafi, A. Ennadi, and M. El Hammoumi/Journal of Engineering Science and Technology Review 10 (4) (2017) 170-177

in the management of construction projects [27]. While taking as a starting point the model of Toyota Production System (TPS), Koskela invented theory TFV (Transformation, Flow, Value) [13] as is shown in Tab. 2.

The most common definitions used in the literature are cited in Tab. 3. Table 3. Definitions of Lean Construction

Fig. 2. The main factors of sustainable development

Table 2. TFV (Transformation-Flow-Value) theory of lean construction

Definitions

Dupin [28]

2014

LC aims to create value for the customer by the elimination of the waste, supported by collaborative project management tools, as part of a systematic and rigorous approach of continuous improvement.

Howell and Ballard [29]

1998

The LC is designed to better meet the needs of customers by using fewer resources.

Koskela [27]

1992

A way to design the production system to minimize waste of materials, time and efforts, in order to generate the maximum possible value of the end product.

Flow

Value

Concept of production

A transformatio n of inputs into outputs

A flow of materials, composed of transformati on processes, inspection processes, movements and waiting

A process where the value for the customer is created by the realization of its requirement s

The main Principle

To have an efficient production

Elimination of waste (non-valueadded activities)

Elimination of the losses of value (value obtained by report to the best possible value)

Practical contributio n

Take care of what must be done

Take care that what is nonnecessary should be reduced to the maximum

Take care to meet customer’s requirement s in the best possible way

3.3 Waste in the construction sector The seven forms of wastes in the construction industry are: waiting, motion, over processing, overproduction, transportation, inventory and defects [30]. Many scientist and professionals consider that the negligence of the seven form of waste by stakeholders during the construction phase is the main cause of the problems of cost overruns and delays in the construction industry [11, 28]. LC considers the construction process as a process flow, combined with transformation activities, contrary to the method of traditional construction which focuses only on the improvement of the steps which create the added value. According to Dupin [28], value-added activities (Direct work) don’t exceed in most of the time 32% of time spent on site, as shown in Fig. 3.

3.2 Definitions of Lean Construction LC philosophy doesn’t have a single definition in the scientific references, it’s still evolving as the academic research, in particular doctoral research, feed this concept.



Year

Overall, it can be concluded that LC is a new way to organize the management of construction projects in such a way as to reduce the sources of waste and generate the maximum value for the customer using the least resources.

3. Lean Construction

Transforma tion

Researchers

Fig. .3. Proportions of activities generating waste in the construction industry

172

M. S. Bajjou, A. Chafi, A. Ennadi, and M. El Hammoumi/Journal of Engineering Science and Technology Review 10 (4) (2017) 170-177

Most searches are focused more on the economic issues of the construction industry and optimization of the triptych (quality, cost, time). Various lean tools and techniques for enabling sustainability have been discussed by several authors. Some studies have explored various issues of sustainability by means of lean initiatives and established the benefits that can be derived by applying the lean principles/tools. This work follows the new paradigm of sustainable management of the construction projects as illustrated in Fig.4.

3.3 Lean Construction tools Many researchers have confirmed the usefulness of the LC concept for projects of construction [4, 15, 31]. The main advantage that companies could reduce the costs invested in construction projects by using fewer resources and reducing waste on production sites. In addition, by having a proper project planning, it would shorten the duration of the construction project. Based on an analysis of the scientific research conducted in several countries, we found that the most appropriate LC for the construction industry are as follows : Last Planner System (LPS), Visual management (VM), 5S, Value Stream Mapping (VSM), Building Information Modeling (BIM), Prefabrication, Analysis of roots causes (5 Why, the Ishikawa diagram , PDCA…), Just In Time, Poka-Yoke, as shown in Tab. 4.



Table 4. Lean Construction tools most used in the construction industry

×

×

×

[9]

×

× ×

×

×

×

×

[28]

×

× ×

×

×

×

×

[33]

×

Poka- Yoke

×

Just In Time

BIM

Root cause analysis Prefabricatio n

VSM

[32]

5S

VM Last planner system

Researche rs

×

Fig. 4. The new paradigm of sustainable management of the construction projects

×

[34]

In this study, we will focus on the direct interaction between five LC tools (Prefabrication, Value Stream Mapping (VSM), Poka-Yoke, Visual Management (MV), and 5 S) and twelve mains factors of sustainable development.

4.1 Prefabrication The existing literature has identified some modern methods as a means of reducing the production of waste in the construction industry. Prefabrication is one of the new techniques to ensure that the components are manufactured and assembled off-site. Several practical cases have shown the efficacy of this technique in reducing waste. For example, the two studies [37, 38] show that the tendency of the waste in the construction projects can be reduced to 52% and 84.7% respectively, compared to the traditional construction. The contribution of prefabrication in promoting the sustainability of construction projects, according to the three facets of sustainable development, is illustrated in Tab. 5.

4. The contribution development

Table 5. The contribution of prefabrication in sustainable development

×

×

[35]

×

×

×

×

×

[30]

×

× ×

×

×

×

[31]

×

×

×

×

×

[11]

×

× ×

of

×

LC

×

tools

×

in

sustainable

Dimensions

The promotion of the economy without taking into account other dimensions of sustainable development will certainly generate adverse effects on the environment and social comfort (health, safety, employment...). As well, the availability of natural resources on our planet (fossil fuels, water, steel, wood...) continues to decrease. Sustainable development is a development that meets the needs of the present without compromising the ability of future generations to meet their own needs. Indeed, Sustainable construction is the response of the construction industry to meet the challenge of sustainable development [31, 36]. In the literature, there is very little research which takes into account the contribution of LC philosophy on the three aspects of sustainable development (economy, environment, society).



Environment

173

Practical contributions

Ref

Reduces the impact on the environment due to the transfer of a large part of the construction process to a specialized factory in prefabrication. All these facts can be translated into many benefits such as less : storage of raw material, noise, air pollution (dust), waste and energy consumption

[34]

Prefabricated components are more likely to be easily

[14]

M. S. Bajjou, A. Chafi, A. Ennadi, and M. El Hammoumi/Journal of Engineering Science and Technology Review 10 (4) (2017) 170-177

Table 6. The contribution of Value Stream Mapping in sustainable development

disassembled in the demolition phase which facilitates their treatments (reuse, recycling, etc) and reduces solid waste

Economy

Selection of non-toxic, reusable and recyclable materials during the design phase.

[39]

Reducing waste on site reduces construction cost, allows to respect the deadline and to increase the quality of the project.

[38]

The development materials

Society

of

new

[14]

Flexibility and adaptability

[14]

Provides safer working conditions (e.g., Reducing dangerous tasks such as welding, cutting that may threaten the worker's safety)

[37]

The strengthening of a prefabrication industry will certainly contribute to the creation of employment opportunities and the development of the technical skills of the staff.

[34]

Dimensions

Practical contributions

Ref [40]

Environment

Allows to measure the consumption of any type of resource (water, energy, materials...), and quantify the sources of pollution (waste, emissions released into the atmosphere) The detection of the sources of waste allows to reduce the financial burden of the project and to shorten the time of completion of the project.

[14]

Economy

Facilitate workflow (load balancing, reducing the complexity of the process, minimizing unnecessary travel ...)

[28]

Society

4.3 Poka-Yoke Poka-Yoke, a Japanese word, is simply a mechatronics device that operates as a mistake-proofing to automatically prevent defects from flowing through the process (Fig. 5). Although this technique was used for the first time by Toyota to improve the quality of its products, the ideas behind this concept could be used to improve the productivity, quality, and safety of staff on construction sites. A typical example, such as controlling the addition of water during the production of mortar, as could be seen in Fig. 6.

Despite the great advantages of prefabrication, this technique shows some disadvantages. At the economic and social level, less labor is requested for projects based on prefabrication, thus fewer employment opportunities especially for staff working on construction sites. At the environmental level, this process can consume more energy for the transport of prefabricated products and emit more air pollution [14, 39]. A contractor applying prefabrication technique in its project should absolutely identify the best method of supply by using a holistic approach during the life cycle of the project.

Fig. 5. Using the Poka-Yoke devices in the construction process

4.2 Value Stream Mapping Value Stream Mapping (VSM) allows to graphically representing the set of steps constituting the construction process in such a way that the user of this technique can easily understand the circulation of the flow (materials, information). According to [14], in contrast to traditional methods the VSM helps to identify activities adding value for the customer and those without added value (non-value added activity). By analyzing the consumption of certain materials (brick, wood, concrete) in the walls construction process Rosenbaum [40] has verified the usefulness of the VSM in promoting the three dimensions of sustainable development. The contribution of the VSM in the promotion of the sustainability of construction projects is shown in Tab. 6. Fig. 6. Using Poka-Yoke devices during mortar production process



174

M. S. Bajjou, A. Chafi, A. Ennadi, and M. El Hammoumi/Journal of Engineering Science and Technology Review 10 (4) (2017) 170-177

Generally, this activity is carried out manually, without any strict control of water consumption which affects the quality of produced mortar. According to Dos Santos [41], the cost lost to solve the problems of non-compliance, errors and changes in construction projects are approaching 10% of the total project cost. The contribution of Poke-Yoke in the promotion of the sustainability of construction projects is shown in Tab. 7.

Make easier the sorting of the solid waste Reduce the variability of the construction process Economy

Table 7. The contribution of Poka-Yoke in sustainable development Dimensions

Practical contributions

[43]

Society

Ref

Strengthens the company position amongst competitors and gives confidence to the customer

[44]

A well-organized workplace allows to security and productivity among employees that the main cause of accidents on construction site is due to disorder noticed in site of construction

[8]

Reduces the consumption of resources (water, materials, energy) Environment Control emissions of pollutants (greenhouse gas, solid waste)

[41]

[41]

Economy

A positive impact on the triptych (quality, cost, time), therefore companies can better respond to customer requirements.

[8]

Society

The Poka-Yoke devices could also protect workers against excessive heat, noise, and some other dangers. In some cases, these devices are used as alarms to prevent labor from approaching or cross (e.g. Fall of objects, concrete in waiting for drying…)

Fig. 7. The traditional method of organizing construction sites

Besides these advantages, the implementation of this technique in construction projects will definitely contribute to the reinforcement of a specialized industry in developing Poka-Yoke devices, so more employment opportunities will be created. Training on this new technology will be necessary to improve the skills of the workforce working on construction and familiarize them with these new devices which lead to ongoing staff development and continuous improvement of the process of construction. 4.4 Visual Management and 5S 5S is the acronym for Sort (Seiri), Simplify (Seiton), Sweep (Seiso), Standardize (Seiketsu), and Self-discipline (Shitsuke). It helps to make a suitable site for the flow of value-added activities by holding everything in its place. The 5S process is considered among the first steps that an organization should take in implementing the LC philosophy. Visual management makes the construction process transparent, simple and safe for all stakeholders on site through digital billboards, signs of security and graphical dashboards. These tools allow to facilitate enormously the construction process and to improve the performance of the communication between the coordinators of the project. The comparison between Fig. 7 and Fig. 8 shows the usefulness of the visual management for the organization and transparency of construction projects [42]. The contribution of the visual management and 5S in the promotion of sustainability of construction projects according to the three facets of sustainable development is shown in Tab. 8.

Fig. 8. Organization of construction sites based on visual Management and 5S

4.4 Synthesis & Discussion Sustainable construction is a new concept that requires checking the objectives of sustainable development at all stages of decision making (design, construction, use, and demolition). In this study, we were based on the analysis of concrete results that have been observed during the execution of several projects of sustainable construction in many countries (United State, United Kingdom, China ...), and especially those adopting a strategy of resources optimization according to the LC philosophy. The objective of this study is to examine the practical relationship that may exist between the LC tools (prefabrication, Value Stream Mapping (VSM), Poka-yoke, visual management (VM), and 5S) and the sustainable development issues, which allows to have a feedback on the

Table 8. The contribution of Visual Management and 5S in sustainable development Dimensions Environment



Practical contributions

Ref

Reduce the waste of materials in stock

175

M. S. Bajjou, A. Chafi, A. Ennadi, and M. El Hammoumi/Journal of Engineering Science and Technology Review 10 (4) (2017) 170-177

level of impacts, either positive or negative, related to the application of the techniques of LC in sustainable construction projects. Tab. 9 represents an Interaction matrix that allows identifying the impacts of the different LC tools studied in this work. These impacts are divided into three categories: environmental, economic, and social.

both positive and negative. At the environmental level, prefabrication brings great benefits for sustainable construction by the use of non-toxic, recyclable, and easily removable materials during the phase of the demolition of building structures. However, this technique requires more energy resources for transportation of prefabricated products, therefore more greenhouse gases will be emitted into the atmosphere. At the social level, the strengthening of a structured prefabrication industry will certainly contribute to the creation of employment opportunities, the development of technical skills of staff and the improvement of working conditions as a result of the transfer of a large part of the process of construction to plants specialized in prefabrication. Even so, there are some problems related to the reduction of certain manual workstations that characterize the traditional construction system, so fewer employment opportunities will be created especially for the staff working on construction sites.

Table 9. The Practical Relationships between Lean Construction Tools and Sustainable Development Prefabrication

VSM

Poka Yoke

5S and visual Management

+

+

+

+

+

+

+

+

±

+

+

+

+

Productivity & Respect of the triptych (cost, quality, time)

+

+

Flexibility

+

Reactivity

+

Innovation / R&D

+

+

Customer satisfaction

+

+

Environment Resources consumption (materials, water, energy...) Pollution Prevention Emission of greenhouse gases Solid waste treatment

5. Conclusion The construction industry represents an integral part that contributes tangibly to the strengthening of the national economy and the reduction of unemployment. Nevertheless, this sector is considered among the main sources of greenhouse gas emissions and solid waste generation. Thus, it is one of the largest consumers of natural resources. Lean Construction is a way to design production systems in order to generate the maximum value for the customer by reducing the waste of materials, time, and efforts. It is a new concept which can bring revolutionary changes and great benefits to the construction industry. In this study, the practical relationships between lean construction tools and sustainable have been extensively explored. It has been established that the LC tools (Prefabrication, Value Stream Mapping, PokaYoke, visual Management &5S have a direct impact in promoting the main factors of sustainable development. Indeed, we have demonstrated that Lean Construction not only contributes to creating the economic value to the construction process but can also contribute to promoting the environmental and social issues. This philosophy represents a strong conceptual basis to achieve the objectives of sustainability. More empirical studies should be conducted in the future to quantify the influence of LC practices on the sustainable construction.

+

Economy +

+

+

+

+

+

+

+

Society Working conditions & Safety Employee involvement / Human resource development Employment

+

+

±

+

Acknowledgement The authors acknowledge the Laboratory of Industrial Techniques, Faculty of Sciences and Techniques of Fez-Morocco, for the provision of research facilities -This work has been supported by CNRST cooperation

This is an Open Access article distributed under the terms of the Tab. 9 shows the practical relationships between the Creative Commons Attribution Licence studied LC tools and the three dimensions of sustainable development (environment, economy, society). Generally, we can notice that most of these tools generate positive impacts on the majority of the issues of sustainable development, except for the prefabrication which could have ______________________________ References 1 2. 3.



Principaux Indicateurs du Secteur du Bâtiment et des Travaux Publics, Ministry of the habitat and city Policy. (2015) 2 p. Tableau de bord sectoriel, Ministry of economy and finance. (2015) 88 p. S. W. Whang and S. Kim, Energy Build. 96 76 (2015).

4. 5.

176

A.A.E. Othman, M.A. Ghaly, and N. Zainul Abidin, Manag. Constr. An Int. J. 6 917 (2014). H. Challot , BTP: 9 millions de tonnes de déchets déversées chaque année dans la nature

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SIX-SIGMA IN LEAN CONSTRUCTION SYSTEMS: OPPORTUNITIES AND CHALLENGES TARIQ S. ABDELHAMID1 ABSTRACT One of the tenants of lean construction states that achieving reliable workflow is possible when sources of variability are controlled. Under a lean paradigm, the effects of variability are buffered through excess inventory, flexible capacity, and/or work-ready backlogs. The common element between these three approaches to tackle production process variability is that they are all attempts to combat the effects of variability and not to reduce or eliminate variability altogether. Reducing or eliminating the variability that plague production processes requires the removal of the root causes of variability –a difficult but not impossible task. Six Sigma is a statistical-based methodology that provides a structured framework to organize and implement strategic process improvement initiatives to attain reductions in process variability. In this paper, the origin of Six Sigma is reviewed with a brief discussion of its methods and metrics. The application of the Six Sigma rolled throughput yield and sigma quality level metrics to the Last Planner System is demonstrated. Using the Lean Project Delivery System as a foundation, the paper suggests Six Sigma applications and research opportunities in Lean Construction. KEY WORDS Six-Sigma, Performance Metrics, Lean Construction, Lean Project Delivery System, Last Planner System

1

Assistant Professor, 207 Farrall Hall, Construction Management Program, Michigan State University, East Lansing, MI 48824-1323. Email: [email protected]

INTRODUCTION Koskela (1992) presented a production management paradigm where production was conceptualised in three complementary ways, namely, as transformation, as flow, and as value generation. This tripartite view of production has lead to the birth of Lean Construction as a discipline that subsumes the transformation-dominated contemporary construction management (Koskela and Howell 2002, Berteslen and Koskela 2002). A profound implication of the TFV concept of production is that it changes the definition of Construction Management from “The judicious allocation of resources to complete a project at budget, on time, and at desired quality” (Clough and Sears 1994) to the “The judicious allocation of resources to transform inputs to outputs while maximizing flow and value to the customer”. Viewing production as flow of materials and information has led to the principle of waste (muda)2 elimination, which was Ohno’s number one enemy (Howell 1999). In fact, Ohno named seven sources of waste in a production process and tirelessly worked on eliminating them. The basic tenant was that removal of waste would result in better workflow (Womack and Jones 1996). This same maxim is emphasized in the lean construction literature (Everett 1992, Koskela 1993, Howell and Ballard 1994, and Howell 1999). An associated principle with waste removal is variability reduction (Berteslen and Koskela 2002). This means that unreliable workflow is indirectly caused by variability (mura)3 stemming from single or multiple causes that need to be targeted separately or collectively. In the construction industry, sources of variability include late delivery of material and equipment, design errors, change orders, equipment breakdowns, tool malfunctions, improper crew utilization, labor strikes, environmental effects, poorly designed production systems, accidents, and physical demands of work (Abdelhamid and Everett 2002). While variability has a myriad of causes it manifests itself mainly in the form of poor workflow reliability between production processes. The damaging and corrupting4 effects of variability on dependent processes has been addressed in Tommelein et al. (1999), Tommelein 2000, and Howell et al. 2001. Additional discussion on the topic can be found in Goldratt (1992), and Hopp and Spearman (2000). Under a lean paradigm, the effects of variability on workflow reliability are mitigated through the use of surge piles, plan buffers, and/or flexible capacity (Ballard and Howell 1998). Surge piles could be in the form of raw and/or processed material. Plan buffers refer mainly to having a backlog of work for crews. Flexible capacity refers to intentional underutilization of a crew or the ability of using a resource in multiple ways by having crosstrained workers. Other examples of flexible capacity can be found in Hopp and Spearman (2000). These three approaches are attempts to combat the effects of variability and not to eliminate variability altogether. In current practice, surge piles or perhaps excess inventory

2 3 4

Muda is Japanese for waste Mura is Japanese for variability Hopp and Spearman (2000) used this term in addressing the effects of variability

prevails over the other two approaches. Practitioners also use efficiency factors or the 45minute productive hour to account for the effects of variability on crew productivity. Schonberger (1986) emphatically states that “variability is the universal enemy” and that reducing variability increases predictability and reduces cycle times. Koskela (1992) adds that reducing process variability will also increase customer satisfaction and decreases the volume of non value-adding activities. The elimination or, more realistically, the reduction of variability requires the identification and removal of the root causes of variability. Koskela (1992) mentions that implementing standard procedures is one strategy to reduce variability in conversion and flow processes. He also mentions Shingo’s “poka-yoke” or mistake-proofing devices and techniques as another strategy to reduce variability. Koskela (1992) also states that statisticians have been battling variability through statistical quality control theory and techniques. This latter strategy has been reinvigorated in the industrial and business sectors through the Motorola-developed Six Sigma approach. Six Sigma is a statistical-based methodology that provides a structured framework to organize and implement strategic product and process improvement initiatives to attain reductions in product and process variability. In this paper, the origin of Six Sigma is reviewed with a brief discussion of its methods and metrics. The use of the rolled throughput yield and sigma quality level metrics is demonstrated using the Last Planner System. Using the Lean Project Delivery System as a foundation, the paper suggests Six Sigma application and research opportunities in Lean Construction. WHAT IS SIX SIGMA? In 1985, Bill Smith of Motorola developed and implemented an approach to achieve nearperfection in product manufacturing called Six Sigma (Breyfogle et al. 2001). Six Sigma refers to a body of statistical and process-based (e.g., process mapping, value stream mapping, etc.) methodologies and techniques used as part of a structured approach for solving production and business process problems plagued with variability in execution (Harry and Schroeder 2000, Pande et al. 2000). Some researchers believe that Motorola developed Six Sigma in an effort to revive Philip Crosby’s (one of the leaders of the quality movement) zero defects approach (Behara et al. 1995). Today, Six Sigma has become a way of life in many other manufacturing organizations (e.g., General Electric, Ford, and Eastman Kodak) as well as in the service industry (Breyfogle 2003). Six Sigma has escaped canonical definition in both the academic and the practitioner literature (Hahn et al. 1999). This is primarily caused by a lack of an abstraction of the underlying theory of the Six Sigma approach. Using Goal theory, Linderman et al. (2003) developed useful theories for the Six Sigma phenomenon. The following definition, suggested by Linderman et al. (2003), embodies the concepts and principles underlying Six Sigma: Six Sigma is an organized and systematic method for strategic process improvement and new product and service development that relies on statistical methods and the scientific method to make dramatic reductions in customer defined defect rates.

While this definition may seem generic for any process improvement initiative, the focus on defect rates is what makes it unique. The defect rates, as defined by an internal or external customer, are caused by product and/or process variability. Reducing variability has been advocated by many of the quality movement leaders such as Deming, Conway, Juran, Crosby, Taguchi, and Shingo (Breyfogle 2003). Thus, Six Sigma emphasizes identifying and avoiding variation. But what also makes Six Sigma unique is the explicit recognition of the correlation among the number of product defects, wasted operating costs, and the level of customer satisfaction. All ‘sigmaists’ know the framework used to achieve Six Sigma goals as DMAIC (Define, Measure, Analyze, Improve, Control). In its formative years, the DMAIC was practiced and perfected on performance improvement initiatives directed at existing processes that resulted in manufacturing defects. Today, the methodology is used for many business processes that fail to meet customer requirements. The DMAIC approach involves (Harry and Schroeder 2000): 1. Defining and understanding the problem being addressed by identifying the critical customer requirements and key factors affecting the process output. 2. Measuring relevant data to the problem primarily through Six Sigma metrics. 3. Analyzing, using statistical quality control tools, the production or business process associated with the problem to identify the root causes. 4. Improving the process using alternatives derived in the analysis phase. 5. Controlling and monitoring the process using statistical process control to sustain the gains and improvements. Another emerging set of steps called Design for Six Sigma (DFSS)5 is used when a product or a process does not exist (radical product or process design) or when incremental changes need to be incorporated into existing products or processes (Breyfogle et al. 2001). DFSS uses existing techniques, such as Quality Function Deployment (QFD), the Axiomatic Design (AD) method, and the theory of inventive problem-solving (TRIZ), to arrive at designs that consider a myriad of issues; performance, assembly, manufacturability, ergonomics, recyclability, reliability, and maintainability (Breyfogle 2003). Companies implementing Six Sigma provide its employees with intensive and differentiated levels of training in six sigma methods (Pande et al 2000, Breyfogle et al . 2001, Linderman et al. 2003). Full-time ‘black-belts’ receive extensive training, usually 4-6 weeks, on the DMAIC or DFSS approaches and are prepared to lead Six Sigma improvement projects. Black belts are coached and instructed by experienced and specially trained individuals called Master Black Belts. Green belts are individuals who provide a supporting (part-time) role on improvement projects and thus receive less training compared to black belts. Six sigma projects are identified and selected by ‘Six Sigma Champions’ who receive macro-level training rather than detailed.

5

Known also as DMADV (Define-Measure-Analyze-Design-Verify)

STATISTICAL DEFINITION OF SIX SIGMA Anyone who has had an elementary course in statistics knows that sigma, σ, is the Greek alphabet used by statisticians to denote the standard deviation of a set of data. The standard deviation (sigma) is (or should be) invariably associated with the calculation of the mean (average) value for a particular set of data. Reporting sigma with the mean value gives an indication of how all the data points vary from the mean. This is important because the mean value alone is misleading as demonstrated by the brilliant analogy of the person that had his/her two feet in a hot oven and the head in a bucket of ice but was on average doing ‘ok’ (Fellows and Liu 2003). However, in the context of the Six Sigma approach, ‘sigma’ has been used as a metric that reflects the ability of a company to manufacture a product or provide a service within prescribed specification limits (or with zero defects). Understanding the statistical origins of the Six Sigma methodology requires an understanding of variability and the characteristics of the normal distribution, which represents many data sets in real life. SIX SIGMA AND VARIABILITY Deming (1986), the father and creator of TQM, stressed that because all things vary, statistical methods are required to control quality or defect rates. Underscoring the importance of variability, Deming (1986) stated: “Statistical Control does not imply absence of defective items. It is a state of random variation, in which the limits of variation are predictable”. Deming, and many others, further defined two kinds of variation: common cause and special cause variation (also known as chance and assignable variation, or chronic and sporadic variation). The former is an inherently random source of variation and addressing it involves a major change in the basic process and operating procedures. The latter is an unusual but controllable source of variation that requires a correction to bring the process or procedures back to its normal levels. Deming asserts that “the difference between these is one of the most difficult things to comprehend” and that it is a futile attempt to address quality problems without understanding the two types of variations. Therefore, Deming recommended that special cause variation be addressed first before addressing common cause variation. To illustrate common cause and special cause variation, consider a manufacturer who produces a product using a single-stage or one-step process as shown in Figure 1. In Figure 1, Xn represents the inputs to the process and Y is the output. Due to variations in the inputs, the resulting Y will also be variable.

Xn

Process

Y

Figure 1: Typical single-stage manufacturing, business, or service process Figure 2 shows the output Y assuming it follows a normal distribution where the ideal target is represented by the mean value. This normality assumption is frequently justified because

the inputs are mutually independent which allows invoking the central limit theorem, i.e., that the sum of mutually independent random variable approaches normality as the number of variables become larger (see Montgomery (2001) for further discussions). Figure 2 is also showing that the manufacturer uses ± three sigma as the lower and upper specification limits for accepting the product Y. This is usually a reflection of the customer’s input and requirements. Note that the use of USL and LSL as ± three sigma is for purposes of explaining the six sigma statistical origin. In real life, customers choose specification limits independent of the normal distribution, or any other distribution.

Lower Specification Limit (LSL)

Upper Specification Limit (USL)

-6σ σ

-5σ σ

-4σ σ

Defects

Ideal value

Defects

-3σ σ

(Y1)

3σ σ

4σ σ

5σ σ

6σ σ

Figure 2: Normal Distribution with specification limits set at ± three sigma Figure 3 is a statistical control chart used to isolate common from special cause variation. The chart shown in Figure 3 shows hypothetical dimension figures for the product Y plotted against time. The Upper and Lower Control Limits (UCL and LCL) shown are a function of the process mean, process range, and the standard deviation of the measured data. It is outside the scope of this paper to expand on the topic of control charts as the there are literally volumes written on the subject in the quality control literature. Montgomery (2001) and Breyfogle (2003) are excellent reference on the topic. By considering the position of the data points on the control chart of Figure 3 relative to the upper and lower control limits, the manufacturer can determine whether the process is under statistical control. A process is considered under statistical control if all the data points fall within the LCL and UCL. Data points falling outside the LCL and UCL are caused by special cause variation. The variation of data points within the same bounds indicates common cause variation, which is inherently inevitable. In the case shown in Figure 3, the process is not under statistical control because there is one measurement, that for part 3, falling below the LCL. This is caused by special cause variation. The reasons behind this should be investigated and eliminated. Because the measurements for the rest of the parts fall between the LCL and UCL, the variation seen is due to common cause variation. However, the common cause variation is excessive because the LSL and USL are violated on the 4th and 5th measurements. Hence, unlike the special cause variation, the reasons behind the variation for these two parts can only be eliminated

through a major change in the basic process. Processes exhibiting such performance are considered to be in control but not capable (Breyfogle 2003). 140

Y1 (critical dimension)

120

U p p e r C o n tro l L im it (U C L )

100

U p p e r S p e c ific a tio n L im it (U S L ) 80 60

L o w e r S p e c ific a tio n L im it (L S L )

40

L o w e r C o n tro l L im it (L C L ) 20 0 0

1

2

3

4

5

6

7

8

9

10

P a rt

Figure 3: Statistical Control Chart -XmR6 (Breyfogle 2003) Turning attention back to Figure 2, it is known that when a data set follows a normal distribution that 99.73 percent of the data points fall within ± three sigma from the mean. Hence, the defects for the process shown in Figure 1 will represent 0.27% (100%-99.73%). When convened to a million ‘Y’ produced parts, the defect rate of the process in Figure 1 is 2700 defects per million parts (ppm). Similarly, if the design specifications allowed ± six sigma variation about the ideal mean, then the process under consideration will have a 0.002 [(100-99.9999998)*10^4)] parts per million (ppm) defect rate. While, 0.002 ppm is considerably less than the 2,700 ppm defect rate, it has been found that the ideal mean value itself is subject to a variation or shift of up to ± 1.5 sigma as shown in Figure 4 (Montgomery 2001). This necessitates an adjustment to both defect rates reported. Hence, for the case shown in Figure 4, 93.32 percent instead of 99.73 percent of the data points now fall within ± three sigma from the mean, i.e., the defects for the process now represent 66,810 [(100-93.32)*10^4] ppm. In the same way, 99.99966 percent instead of 99.9999998 percent of the data points now fall within ± six sigma from the mean, which translates to a defect rate of 3.4 ppm. Motorola used this level of sigma quality as its goal and the Six Sigma movement was born. As mentioned earlier, in the Six Sigma approach a ‘sigma’ quality level is used as a metric that reflects the ability of a company to manufacture a product or provide a service within prescribed specification limits (or with zero defects). Figure 5 shows the defective parts per million (ppm) and the associated sigma quality level (Breyfogle 2003)7. As shown in Figure 5, the relation between the defect rates and the sigma quality level is not linear. For example, a 6 sigma quality level indicates that a company is operating with only 3.4 defects

6

7

XmR stands for a control chart that uses process values obtained from one sample set to calculate process mean. A moving range is typically also constructed. Hence, the designation XmR. Sigma Quality Level = 0.8406 + [29.37-2.221 × ln(ppm)]^1/2

per million parts, units, or operations, while a company operating at 3 sigma quality level has a defect rate of 66,810 ppm. Normal Distribution shifted ±1.5 σ

Lower Specification Limit (LSL)

Upper Specification Limit (USL)

Defects

Defects Ideal value

-6σ σ

-5σ σ

-4σ σ

-3σ σ

3σ σ

(Y1)

4σ σ

5σ σ

6σ σ

Figure 4: Normal distribution with ±1.5 sigma shift

Defective parts per million

800,000 700,000

697,672

600,000

501,350

500,000 400,000

308,770

300,000 158,687

200,000

66,810

100,000

22,750 6,210 1,350 233

32

3.4

5.5

6

0 1

1.5

2

2.5

3

3.5

4

4.5

5

Sigma Quality Level

Figure 5: Defects per million and Sigma quality level To better appreciate the magnitude of difference between the different sigma levels, the following spelling mistakes are provided as an example (Breyfogle 2001): •

Sigma level one: 170 misspelled words per page in a book

•

Sigma level two: 25 misspelled words per page in a book

•

Sigma level three: 1.5 misspelled words per page in a book

•

Sigma level four: 1 misspelled words per 30 pages in a book

•

Sigma level five: 1 misspelled word in a set of encyclopaedias

•

Sigma level six: 1 misspelled word in all the books in a small library

•

Sigma level seven: 1 misspelled word in all the books in several large libraries

On average, most US manufacturing and service industry firms rate between three and four sigma. Companies operating at the six sigma level in the short term and at the 4.5 sigma level for the long term are considered to be ‘best in class’. It is worth noting that the US domestic airline flights fatality rate is between 6 and 7 sigma, i.e., at 0.43 ppm (Breyfogle 2003). Thus far, the discussion has only addressed a single-step process. For multi-step processes, each step will have its associated sigma quality level or defect rate. The statistically independent yields for each step are multiplied to arrive at the overall yield or defect rate (Behara et al. 1995). Table 1 shows the overall yield for a single process up to a process with 1000 steps. As an example, consider a 10-step process with a desired 4 sigma level. The overall yield for the process as shown in Table 1 is 93.96 percent. Hence, 6.04 percent will be the resulting defect rate (or 60,400 ppm). Note that this defect rate is roughly ten times more compared to that from a single process at the same sigma level (at 6,210 ppm). The numbers shown in Table 1 underscore the importance of simplifying and reducing the number of processes involved in producing a part, completing a service, building a structure, etc. In addition, having multi-stage processes makes it rather difficult to achieve a six sigma quality level. However, not all companies should consider this as the appropriate level. Rather the appropriate sigma quality level should be based on the strategic importance of the process and the cost to benefit ratio expected (Linderman et al 2003, Breyfogle 2003). Table 1: Overall yield and associated sigma quality level (Behara et al. 1994) Number of stages/parts 1 10 100 1000

± 3 sigma

± 4 sigma

± 5 sigma

± 6 sigma

93.32 50.088 0.10 0.0

99.379 93.96 53.64 0.20

99.9767 99.768 97.7 79.24

99.99966 99.9966 99.966 99.661

SIX SIGMA AND TQM Despite the success of Six Sigma and its role in rejuvenating the quality movement, it has come under fire from the quality community itself. Some have criticized the used of the 1.5 sigma shift and considered it an attempt to correct for the ubiquitous use of the normal distribution with its inherent oversimplifications. Others considered the 3.4 ppm defects rate an inappropriate goal for all businesses. Proponents of six sigma acknowledge that six sigma is not perfect but that it has shown deserved success and that taking six sigma’s statistical 8

50.08% = (93.32%)^10

definition literally overlooks that it has now become associated with the tireless pursuit of customer satisfaction through higher levels of quality and lower levels of cost (Hammer and Goding 2001). In fact, not only did Six Sigma break away from its statistical definition of quality, it has also managed to break away from its initial focus on minimizing the variations or defects of manufactured products where it is now being applied to many business and service processes (e.g., billing, patient care, software programming, payroll, etc.) Perhaps the most common mischaracterization of six sigma is that it is “TQM on steroids” and that it is nothing new. Breyfogle et al. (2001) quotes Tom Pyzdek saying: “Six Sigma is such a drastic extension of the old idea of statistical quality control as to be an entirely different subject….In short, Six Sigma is ….an entirely new way to mange an organization…Six Sigma is not primarily a technical program; it’s a management program”. Many others have dismissed the TQM uplift as irrelevant especially that six sigma does not place the same preeminence TQM placed on quality at the expense of all other business aspects (Harry and Schroeder 2000, Pande et al. 2000, Breyfogle 2003). SIX SIGMA METRICS Organizations implementing Six Sigma must select metrics against which progress and improvements can be assessed. To facilitate comparison and benchmarking to competitors or even other industries, a number of six sigma metrics have been created and are in use. Rolled throughput yield (YRT), defects per million opportunities (DPMO), process capability (Ck and Cpk) and process performance (Pk and Ppk) are examples of these metrics. Of these, rolled throughput yield (YRT) will be discussed as conceived under Six Sigma and then later adapted for use in the Last Planner System. SIX SIGMA YIELD For most organizations, yield (Y) represents the percentage of units that pass final inspection relative to the number of units that were processed. Mathematically, the yield represents the area under the probability density curve between design specification limits (Breyfogle 2003). Using the Poisson distribution as an approximation of the normal distribution (see Figure 6), the yield denotes the probability of having zero defects. Breyfogle (2003) shows yield in equation form as Y = P ( x = 0) =

e −λ λx = e − λ = e − DPU x!

(1)

where λ is the mean of the distribution equal in this case to the defects per unit, DPU. Note also that x represents the number of failures.

Specification Limit

Yield = e

-DPU

Defects

Figure 6: Process Yield and Defects (Breyfogle 2003) The definition of the yield should not be associated with manufacturing operations only. In any industry where a product or service is provided, a process yield can be identified. This metric, however, can mask the rework that takes place prior to final release, which is the metaphoric ‘hidden factory’ that Lean and Six Sigma advocate identifying and eliminating. Exposing the ‘hidden factory’ is facilitated in Six Sigma projects through the use of rolled throughput yield (YRT). YRT is the product of the yield of each process (or sub-process) required to produce a unit or a service. To illustrate the difference between Y and YRT, Figure 7 shows a 3-stage process with the yield, rework, and scrap at each stage. The process shown in the dashed box of Figure 7 represents how the yield is calculated using conventional means. For example, when 100 units are processed through the first process, which has an established yield of 90%, only 90 units will be acceptable or accomplished. The remaining 10 are re-routed through the ‘hidden factory’ where, as assumed here, 6 are re-worked successfully and 4 are scrapped. In this case, the final units reported, or that will end-up showing as ‘finished goods’, will be 96 (90+6) and not 90. This same calculation is used for process 2 and 3. Finally, the 3-stage process appears to have a yield rate of 90% (90/100). Rework 6 units

100units

Y1 = 0.90 Rework 19 units

96units

94 units

Rolled Throughput Yield

96 units (100-4)

90 units

75 units

94 units (75+19)

70 units (90*0.78)

80 units

90 units (80+10)

90 units

Scrap 2 units

Y2 = 0.78 Rework 10 units

Process Yield (with rework)

Scrap 4 units

Scrap 4 units

Y3 = 0.85

Process Yield = 90 / 100 = 90%

59 units (70*0.85)

Rolled Throughput Yield = 59 / 100 = 59%

Figure 7: Conventional process yields vs. Six Sigma’s rolled throughout yield Using the Six Sigma rolled throughput yield metric gives an entirely different perspective on the yield. In this case, the output from the first process (the 90 units) is used as the input for

the second process without reflecting the rework. Consequently, the output for the second process is considered as the input of 90 units multiplied by the yield Y2 (at 78%) giving a total of 70 units. These 70 units are again considered as the input for the third process, without the rework, and so on. The use of rolled throughput yield indicates that the 3-stage process has a 59% yield and not the 90% reported by conventional yield calculations. This exposes the hidden factory and gives more insights into process performance. It is worth noting that the rolled throughput yield shown in Figure 7 is also the product of the three individual yield values, i.e. 0.90*0.78*0.85 = 59%. Hence, in equation form, rolled throughput yield is

YRT = ∏i =1 Yi m

(2)

where m is the number of processes involved and Yi is the throughput yield of process i. To facilitate comparison of processes performed at different locations, e.g., by peer companies or even across industries, the rolled throughput yield is normalized and a sigma quality level is calculated. This is performed using the following set of equations (see Breyfogle (2003) for more discussion): (3)9

Ynorm = m YRT and using (1) it can be shown that

DPU norm = − ln(Ynorm )

(4)

where DPU stands for the defects per unit. To determine the sigma quality level, also called Zbenchmark, for the processes under consideration, the following equation is used: Z benchmark = Z DPU norm + 1.5

(5)

where ZDPUnorm is the standard normal value corresponding to the DPUnorm found using Equation 4. To illustrate the use of Equations 3-5, the 3-stage process in Figure 7 is used: 1. Using Equation 3, Y norm = m Y RT = 3 0.59 = 0.8387

2. Equation 4 gives a DPU norm = − ln(Y norm ) = − ln(0.8387) = 0.1759 3. The standard normal table shows that Z DPU norm = 0.93 , hence, Z benchmark = Z DPU norm + 1.5 = 0.93 + 1.5 = 2.43

Therefore, the 3-step process shown in Figure 7 is operating at a 2.43 sigma quality level. This can be converted to a parts per million rate using

PPM = e

9

     

29.37−( SigmaQualityLevel −0.8406)2    2.221  

This equation is essentially the geometric mean of a set of data.

(6)

Using Equation 6, the ppm rate of this process is 177,435. For a single step process, the same equations can be used but without normalizing the yield and noting that the rolled throughput yield is the same as the throughput yield. For example, consider that the sigma quality level of stage 2 in Figure 7 was of interest. To determine that, the following steps are followed: 1. Using Y2 = 0.78 in Equation 4 gives a DPU = − ln(Y2 ) = − ln(0.78) = 0.2484

standard normal table shows 2. The Z benchmark = Z DPU + 1.5 = 0.68 + 1.5 = 2.18

that

Z DPU = 0.68 ,

hence,

Hence, stage 2 is operating at a 2.18 sigma quality level that, using Equation 6, gives a ppm rate of 246,725. YIELD AND THE LAST PLANNER SYSTEM®

The Last Planner System® (LPS) provides a framework for management and workers to plan and control daily production assignments (Ballard 1999). Daily assignments are viewed as commitments that a production unit makes to other downstream units. A detailed explanation of the LPS is beyond the scope of this paper and can be found in Ballard (2000). The Last Planner System uses Percent Plan Complete (PPC) as a metric to measure the quality of the commitments made and the reliability of workflow. PPC is the number of completed assignments expressed as a ratio of the total number of assignments made in a given week. This metric is usually reported for a particular trade or crew on a daily or weekly basis. Figure 8 shows PPC data collected by Chitla (2003) for a paint ceiling job in a manufactured housing facility where houses are built on an assembly line. The average daily PPC for the crew in Figure 8 is 68%. Paint Ceiling Workstation 1.00

1.00 Crew 1

0.90 0.80

0.75

0.70

0.67

0.67

PPC

0.60 0.50 0.40 0.30

0.33

0.20 0.10 0.00 Day 1

Day 2

Day 3

Day 4

Day 5

Figure 8: PPC for Paint Ceiling Figure 9, also from Chitla (2003), shows PPC for 10 different workstations along the assembly line of the same plant. The PPC in Figure 9 was calculated using data collected

0.81

0.81 0.73

0.68

nd

w

in do w Ex s te rn al sid in Ex g te rn al fin ish Ro of tru ss Pa in tc ei lin g Ro of bo ar ds

oa rd s rb D oo

rs a

rw al ls

Ex te rio

0.88

le s

0.83

0.63

Ex te rio

er io In t

0.83

0.76

ng

0.78

Sh i

1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 rw al ls

PPC

over 10 days for each station. According to the PPC data in Figure 9, the average PPC for the entire plant is 78%.

Observed stations

Figure 9: Manufacturing Plant PPC The PPC averages reported at both the crew level and the plant level reflect fluctuations in production planning and workflow reliability. Recall that the yield (Y) represented the percentage of units that pass final inspection relative to the number of units that were processed. Contrasting the PPC metric to the definition of the yield reveals similarities because both reflect a ‘completion rate’. Consequently, using an average PPC to report the overall plant throughput would also mask the ‘hidden’ factory as discussed before in the case of the yield. Therefore, it seems prudent to extend the Six Sigma rolled throughput yield (YRT ) to the PPC metric. This is accomplished by adapting equations 2-5 as follows: PPC R = ∏i =1 PPCi

(7)

PPCnorm = m PPC R

(8)

MAPPnorm = − ln( PPC norm )

(9)

m

where PPCR is rolled PPC, m is the number of processes involved, and PPCi is the PPC of process i.

where MAPP stands for missed assignments per plan. Z benchmark = Z MAPPnorm + 1.5

(10)

where ZMAPPnorm is the standard normal value corresponding to the MAPPnorm found using Equation 9. To illustrate the use of equation 7-10, the 10-stage process in Figure 9 was considered and the following results were obtained: 4. Equation 7 gives a PPCR = 0.085

5. Using Equation 8, PPCnorm = 10 PPC R = 10 0.085 = 0.782 6. Equation 9 gives a MAPPnorm = − ln( PPC norm ) = − ln(0.782) = 0.246 7. The standard normal table shows that Z MAPPnorm = 0.69 , hence, Z benchmark = Z MAPPnorm + 1.5 = 0.69 + 1.5 = 2.19 .

Therefore, the 10-step process shown in Figure 9 is operating at a 2.19 sigma quality level that, using equation 6, is equivalent to 243,757 ppm. The average PPC reported for the single process of painting the ceiling can be also converted to a sigma quality level as follows: 1. Using PPC = 0.68 in Equation 9 which gives a MAPP = − ln( PPC ) = − ln(0.68) = 0.3857

2. The standard normal table shows that Z MAPP = 0.29 , hence, Z benchmark = Z MAPP + 1.5 = 0.29 + 1.5 = 1.79 . Hence, the ceiling painting process is operating at a 1.79 sigma quality level that is equivalent to a ppm rate of 368,773. Using the Six Sigma based rolled PPC metric facilitates the comparison of performance against other plant locations as well as other companies. In addition, the rolled PPC exposes the hidden factory that was masked by the average plant-level PPC. While the average PPC value reported for painting the ceiling could be used for comparisons with other operations on the line, the principle benefit of finding the sigma quality level is to give a better sense of the magnitude of the process performance failure. In other words, reporting that the process is 32% off-target is not the same as stating that the process is operating with a defect rate of 368,773 ppm. SIX SIGMA AND LEAN CONSTRUCTION

The synergy, or lack thereof, between six sigma and lean production is a point of contention between people on either camp. The balanced perspective on this issue states that by working in unison, Lean and Six Sigma represent a potent framework in eliminating process variation. Breyfogle et al. (2001) states: “In a system that combines the two philosophies, lean creates the standard and Six Sigma investigates and resolves any variation from the standard”. Stated in a different way, while lean identifies Muda, Six Sigma eliminates Mura. Moreover, Six Sigma is considered a great tool for problems that are ‘hard to find but easy to fix’. Problems of the ‘easy to find but hard to fix’ category are better addressed using lean production tools (Hammer and Goding 2001). To find candidates for the implementation of the Six Sigma methodology, the Lean Project Delivery System (LPDS) was used. LPDS is a conceptual framework developed by Ballard (2000) to guide the implementation of lean construction on project-based production systems, i.e., the structures we build. LPDS was depicted as a model with 5 main phases, where each phase is comprised of three modules. The inter-dependence between the phases (e.g. that design of product and process should be performed concurrently) was represented

by sharing one module between two subsequent phases. Production control and lean work structuring were both shown to extend throughout the 5 main phases. Learning or (postoccupancy evaluation) was introduced to underscore the need to document lessons learned from one engagement to another. The reader is referred to Ballard (2000) for a detailed account of the LPDS model. Figure 10 represents the author’s adaptation of the LPDS model. This depiction of the LPDS model as compared to its original ‘triad’-based illustration was primarily a response to suggestions by graduate students in a Lean Construction course taught by the author at Michigan State University. In addition, using the format of Figure 10, it was easier to superimpose the Six Sigma methodology most suited for the different modules of the LPDS model. It is worth noting that the numbers in the encircled and octagon bound modules represent the phase that the module belongs to. The modules with two numbers represent the modules that are shared between two different phases. For example, the module ‘Product Design’ is part of both the ‘Lean Design’ and the ‘Lean Supply’ phases.

USE Project Definition Purposes 1 Design Criteria 1

KNOW WHAT THE OWNER REALLY WANTS

Design Concepts 1/2 Process Design 2

Lean Design Product and Process; Suppliers Design, strategic alliances with suppliers

Operation Maintenance 5 Commissioning 5 Learning

Work Structuring Production Control

Detailed Engn. 3

Alteration Decomm. 4/5

USE DFSS

Lean Assembly

Installation 4

Learning Product Design 2/3

USE DMAIC

Fab. Logistics 3/4

Lean Supply

JIT, Modularize Standardize, industrialize...

Figure 10: Lean Project Delivery System and Six Sigma In Figure 10, modules bounded by an octagon are candidates for the DMAIC approach because this approach is suited for investigating and improving existing processes. For example, fabricators can utilize this approach to investigate and improve processes that exceed the allowable tolerances (the Doors and Frames case study in Tsao et al. 2000). Another example is on-site assembly or installation processes suffering from variability in performance due to late delivery of material and equipment, design errors, change orders, machine breakdowns, environmental effects, occupational accidents, and poorly designed

production systems. The DMAIC approach can help in identifying and eliminating the root causes behind these problems. Similarly, encircled modules in Figure 10 are candidates for the DFSS approach which is most suited for new products or processes or when incremental changes need to be incorporated into existing products or processes. The methods used in DFSS are an extension of those used in DMAIC for existing (repetitive) processes. The goal of DFSS is to meet customer (internal and external) requirements from the start. This is especially important for project-based production systems where a customer requirement is usually met under a tight budget and schedule constraints. Recognizing the role that Six Sigma initiatives are playing and will play in the future, the Primavera group has developed a software called TeamPlay which provides organizations with the tools to select and implement Six Sigma projects. TeamPlay has a host of tools that allow the identification of ‘key improvement areas’, and applying the DMAIC and the DFSS method. This is not in any way an endorsement of this software product but it is a resource that could be investigated. CONCLUSION

This paper described the Six Sigma methodology that was developed at Motorola in 1985 and is now used by many organizations to attain reductions in process variability. The paper discussed the definition of Six Sigma and its statistical origin. The DMAIC and DFSS methods and metrics used in Six Sigma were briefly presented. A Six Sigma modification was also introduced to the Last Planner System through the use of the rolled throughput yield metric and sigma quality levels. Using the Lean Project Delivery System as a foundation, the paper suggested Six Sigma application opportunities in Lean Construction. This paper considered the tip of the iceberg when it comes to the ever expanding and evolving area of Six Sigma. Additional research is needed to investigate the implementation of Six Sigma methods in Lean Construction. Some researchers may consider starting with the LPDS-identified areas as presented in this paper. Others may choose other avenues. In general, in any implementation effort of Six Sigma it must be recognized that it is a tool among many and that it is suited for a particular type of business problems while entirely useless for others. Six Sigma is a great tool for problems that are ‘hard to find but easy to fix’. Lean tools are great for ‘easy to find but hard to fix’ problems (Hammer and Goding 2001). REFERENCES

Abdelhamid, T. S., and Everett, J. G. (2002). “Physical demands of construction work: A source of workflow unreliability”. Proceedings of the 10th Conference of the International Group for Lean Construction, Gramado, Brazil, August 6-8. Ballard, G. (2000). The Last Planner System of Production Control. PhD dissertation, University of Birmingham, UK. Ballard, G. (1999). “Improving Work Flow Reliability”. Proceedings of the 7th Conference of the International Group for Lean Construction, Berkeley, California, USA, 26-28 July 1999.