Ankit Energy Audit Report
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CONTENTS Executive Summary
01
1: Introduction
02
2: Historical Energy Consumption
03
2.1: Gas Purchase History
04
2.2: Electricity Purchase History
05
2.3: Energy Use Index
11
2.4: Tariff Analysis
11
3: Energy end‐uses
14
3.1: Summary of HVAC operation
15
3.2: Space Heating
17
3.3: Lighting
18
3.4: Other Electrical End‐Uses
20
4: Energy Management
21
4.1: Monitoring and Targeting
21
4.2: Investment
21
4.3: Policy
21
4.4: Technical
22
5: Recommendations
23
Appendix A: Energy Purchase Records and Pricing Details
26
Appendix B: Energy Balance
31
Appendix C: Schematic of the plant
33
Appendix D: Product Information
34
Executive Summary This report documents the savings opportunities and assesses the energy consumption found during the energy audit of the Pataka Building situated in Porirua, Wellington. Total annual energy use is shown below: Energy Source Natural Gas Electric Energy Total
Annual Usage (kWh/yr) 406,656 650,008
Average Price (c/kWh)
Annual Cost ($) 3.61 (energy + fixed charges) 14,689 12.54 (energy + fixed charges) 81,519 1,056,664 9.10 96,208 Table 1: Annual Energy Use
The price that the building pays for natural gas is about what one would expect however; for electricity savings could be made after the negotiated contract is over. The energy use index (EUI) for the Pataka building is 176 kWh/m2yr (as calculated in section 2.3). This is below the typical figure for commercial buildings in New Zealand, which generally use about 200 kWh/m2yr. As the library and the museum use the most energy, the EUI for just those particular areas is about 278 kWh/m2yr, which is higher than the benchmark. The distribution of energy by end‐use is shown in the pie chart below.
Figure 1: Distribution of Energy Use by End‐Use
Recommendations are documented through the observations being made which include: ‐ Turning unnecessary lights off and using natural light efficiently. ‐ Replacing existing lights with eco energy efficiency lights. ‐ Maintaining services regularly and repairing damage as soon as possible. 1
1: Introduction This report describes the energy consumption and savings opportunities for the Pataka Building located at Paramoana Street, Porirua. The Pataka building consists of a library, a museum, a performance space, a foyer space and a café, all contributing to the annual energy use of the building. The building is owned by the Porirua City Council and therefore; is a building for the people of Porirua City and the general public. It provides recreational and leisure activities for the general public and a place to experience the art and the culture of Porirua City. The walk through of the building services took place on 24 March 2008 with subsequent daytime visits till date. Observations and measurements were carried out to assess the current situation and provide recommendations based on the assessments. The building covers two levels and has a floor area of approximately 6014m2. It consists of materials that provide potential for thermal mass and has an exposed northern façade and a roof top which catches full sun and provides sufficient daylighting into the library and the foyer space. This also, provides substantial solar gain into the spaces creating over heating issues during summer but comfort during winter. The main finding of the audit is that the energy consumption of the building has increased compared to previous years. This could be caused by the services not running properly. The BMS needs to be properly configured and maintained for different seasons in order to provide comfort and reduce energy use. There are many opportunities to reduce the energy usage at low or no cost. The building poses some interesting challenges in energy management as it comprises of different usage of spaces within the fabric of the building. It consists of different spaces which have their own individual needs to provide comfort.
2
2: Historical Energy Consumption The Pataka Building in Porirua, Wellington uses both natural gas and electricity as its sources of purchased energy. The annual energy use and cost (excluding GST) from the available data (as shown in Appendix A) is summarized in Table 2 below. Energy Source Natural Gas Electric Energy Total
Annual Usage (kWh/yr) 406,656 650,008 1,056,664
Average Price (c/kWh)
Annual Cost ($) 3.61 (energy + fixed charges) 14,689 12.54 (energy + fixed charges) 81,519 9.10 96,208
Table 2: Annual Energy Consumption
Annual electricity and gas use is based on the consumption from 1 January 2007 to 31 December 2007. The contribution of each energy source to both annual energy use and annual energy cost is shown in Figure 2 below.
Figure 2: Energy sources as a percentage of annual use (left) and annual cost (right)
3
2.1: Gas Purchase History Historic gas use is plotted in Figure 3 below, as the average kWh/day. The data for this graph is in Appendix A.4.
Figure 3: Average Daily Natural Gas Consumption from Jan 05‐Dec07
As expected, the gas use is significantly higher in winter than in summer. This is because all of the natural gas is used for space heating purpose and therefore; winter loads are much higher compared to summer loads. The annual gas usage is up by 4% from 2005‐2006 however, the gas usage from 2006‐2007 is down by 15%, as shown in Appendix A.4. This decrease could have caused, due to outside temperatures being higher and as a result, space heating is not needed as much. The annual daily gas consumption in 2006 and 2007 is plotted against outside temperatures as shown in Figure 4. This provides a much better understanding of gas use compared to outside temperature. The graph was taken from the e‐bench website which records daily climatic conditions and gas usage for the site. Gas use is highly seasonal, with average winter use being 1830 kWh/day, approximately 3‐4 times higher than the average summer use being 580 kWh/day. 4
Figure 4: Annual Daily Gas Consumption in 2006 and 2007 plotted against outside mean temperature
2.2: Electricity Purchase History Historic electricity use is plotted in Figure 5 below, as the average kWh/day. The data for this graph is in Appendix A.1. Figure 5: Average Daily Electricity Use from Jan 05‐Dec07
5
The graph shows a reverse seasonal pattern. Usually, electricity loads are higher in winter compared to summer however; for this case, the electrical energy is being used more in summer than winter. This is because the electricity is being used by the air conditioning units during summer for cooling and therefore; the loads are slightly higher during the summer months. The electricity usage from 2005‐2007 has remained quite constant. It has only increased by 4%. The average electricity use (approximately 1,708 kWh/day) would mostly be used for cooling, lighting and heating water. On the other hand, annual electricity cost has increased 17% over the same frame due to increased electricity charges. The daily cost of electricity has also increased significantly from 2005‐2006 but a slight increase from 2006‐07 as represented by Figure 6 below. Figure 6: Average daily cost of electricity use from 2005‐2007
The half‐hourly electricity use for February 2007 is plotted in Figures 7 and 8 below. These show the day‐to‐day and hour‐to‐hour patterns of electricity use during a summer month. 6
Figure 7: February 2007 Electricity Use
Figure 7 shows the electric energy use in the middle of summer. The point directly above the mark on the time axis represents midnight, and the space between the peaks, 24 hours. The daily patterns are quite consistent. Figure 8 shows the same data, but all the daily load patterns have been plotted on top of each other to establish an average load profile. This can therefore determine hour‐to‐hour trends as shown below. Figure 8: February 2007 Electricity Use – Average Daily Patterns
7
The solid bold black line represents the average weekday loads, whilst the dashed line represents the average weekend load. As can be seen, average electricity demand in the evening and the early morning is at its minimum of about 38kW. The rise in electricity use starts at about 8am and climbs to approximately 115kW during the midday period where it is at its peak. The load remains consistent after that however; it starts to decline slowly and then a significant drop as the demand for electricity reduces. This is because the main areas of the building which include the library and the museum close after 5.30pm and as a result, less electricity demand is needed. The graph for weekend use follows the same pattern however; less demand is used due to the less occupancy in the building. Offices and other management areas are closed therefore; less energy is consumed. Figures 9 and 10 represent the half‐hourly patterns of electricity use for July 2007. These show the day‐to‐day and hour‐to‐hour patterns of electricity use during a winter month.
Figure 9: July 2007 Electricity Use
8
Figure 9 shows the electric energy use in the middle of winter. The daily patterns are quite consistent and similar to the February patterns. The load variability remains consistent throughout the month and there is no significant peak or drop noticed compared to the February month. Figure 10 shows the same data, but all the daily load patterns have been plotted on top of each other to establish an average load profile for the winter month. This can therefore determine hour‐to‐hour trends as shown below.
Figure 10: July 2007 Electricity Use – Average Daily Patterns
As can be seen, average electricity demand in the evening and the early morning is at its minimum of about 50kW. The rise in electricity use starts at about 8am and climbs to approximately 125kW during the midday period where it is at its peak. The load starts to decline slowly and then a significant drop as the demand for electricity reduces. The graph for weekend use follows the same pattern however; the peak demand reaches at 125kW at approximately 11am and slowly drops as the day progresses. 9
From the established load profiles for February and July, it can be seen that energy demand increases during the winter month compared to the summer month. This is most possibly due to the heating pumps and humidifiers utilizing more energy during the winter month. The humidifiers would be operating more as the outside temperature and humidity affect the museum spaces. Also, there are three hot water cylinders which would increase the demand for electricity during the winter month. The breakdown of annual electricity consumption by area was also determined as shown in Figure 11 below. This data was established through the various sub meters which record electricity consumption by each area. The data was given by the Library manager who keeps records of the energy use by area (shown in Appendix A.3). Figure 11: Breakdown of Annual Electricity Consumption by Area within the Building
As can be seen, the museum consumes a substantial amount of electrical energy compared to the other areas of the building. This is quite unusual as the museum is less occupied than the library. However, services such as humidifiers are running all day throughout the whole year to provide comfort and prevent damage. Also, the artifacts room has to be well controlled in order to prevent damage. 10
2.3: Energy Use Index The energy use index (EUI) is the annual energy consumption of the building, divided by its floor area. The net area of the building is approximately 6014m2. The total annual energy consumption is approximately 1,056,664 kWh, consisting of 650,008 kWh of electricity and 406,656 kWh of gas. Therefore, the energy use index is: 1,056,664kWh/yr / 6014m2 = 176 kWh/m2.yr A typical EUI for commercial buildings is 200kWh/m2.yr of Net Lettable Area. 1 The EUI for the Pataka building is 176 kWh/m2.yr, which is slightly lower than the benchmark. As the library and the museum use the most energy, the annual energy use of the main areas can be carried out to determine the EUI for those particular areas of the building. The net area of the two main spaces is approximately 3796 m2 and therefore; the EUI can be calculated to be approximately 278 kWh/m2.yr, which is higher than the benchmark however; further investigation is needed to carry out an accurate EUI for the two main energy consuming areas of the building. 2.4: Tariff Analysis Electricity The electricity for the Pataka Building is supplied by Meridian Energy. Porirua City Council (PCC), the owners of the building have negotiated an electricity supply contract with Meridian Energy. The contract prices are 100% fixed for three years, though the rates vary for different times of the day, weekday to weekend day and month to month. The prices negotiated are in four hour blocks during business and non‐business day with higher prices during the time between 8am – 12 pm and 4pm – 8pm as shown in Appendix A.2. The prices are higher when the peak demand is high as shown in the load profile graphs (figures 8 and 10).
1
AS/NZS 4220: 1982 Energy Conservation in Non‐Residential Building, p.9
11
Over the past year the average electricity paid by PCC has been averaged 12.52 c/kWh inclusive of both energy and fixed charges. Each month has also, been calculated which can be viewed in Appendix A. Network services are provided by Vector Networks. The Pataka building has been on the G46 rate which is for sites with dedicated transformers greater than 300kVA. The G46 rate includes: ‐ A fixed rate of 0.0337 $/day ‐ anytime maximum demand rate of 8.0151 $/kVA/month – based on the single highest demand in each month – any time of the day ‐ coincident maximum demand rate of 3.3996 $/kVA/month – based on the single highest demand occurring between 7.30am and 9.30am, and 5.30pm and 7.30pm on weekdays (including public holidays). ‐ Capacity rate of 0.5223 $/KVA/month – based on the installed transformer capacity, in this case 300kVA. This particular rate was the best option for the Pataka building to be on however; new charges as at 1 April 2008 have been made which is shown below. ‐ A fixed rate of 16.4835 $/day ‐ Anytime maximum demand rate of 5.3476 $/kVA/month – based on the single highest demand in each month – any time of the day ‐ Capacity rate of 0.0137 $/KVA/month – based on the installed transformer capacity, in this case 300kVA. ‐ A variable charge is introduced at 0.58 c/kWh. These changes are shown below in Table 3. The new network charges are lower by $200 per month and there is less incentive to control the maximum demand.
Charge
2007/08‐ old ($)
2008/09 – new ($)
Daily AMD CMD Capacity Variable Total
0.337 8.0151 3.3996 0.5223 0
Cost March 08 ($)
16.4835 5.3476 0 0.0137 0.0058
10.5 1492 592 157 0 2252
Cost April 08 ($) 511 990 0 123 431 2055
Table 3: Comparison of old and new network charges
12
Gas Gas is supplied by Nova Gas. Over the past year the average electricity paid by PCC has been averaged 3.61 c/kWh inclusive of both energy and fixed charges. Each month has also, been calculated which can be viewed in Appendix A.4. Gas charges include: ‐ Consumption charge of 9.9614 $/GJ = 3.4 c/kWh ‐ Gas Industry Company Levy of 0.0178 $/GJ ‐ ICP Levy of 0.0173 $/day 13
3: Energy end‐uses The layout of the Pataka building is shown in Figure 12 below. Office spaces within the library and the museum are shaded. The void area is an outdoor open area mainly used by the café. The layout shows where each space is within the building and represents the spaces which consume the most energy apart from the void.
Figure 12: Layout of the Building
The Pataka building uses both natural gas and electricity. The gas is used for space heating and all the other end‐uses consume electricity. The estimated distribution of energy end‐uses on an annual basis is shown in Figure 13 below. Figure 13: Estimated Annual Distribution of Energy End‐uses
14
The energy distribution graph is determined from the energy balance carried out for the building, as described in Appendix B. As can be seen, space heating is the largest energy end‐ use, accounting for 39% of the total annual energy consumption. The second largest end‐use is the HVAC, which consumes 27% of the total energy. The lighting uses about 23% of the total energy and office equipment, other equipment, kitchen equipment and the Library HVAC make up the rest of the energy use. Each major end‐use is discussed separately, in the following section. 3.1: Summary of HVAC operation Library The library area is heated by air conditioning units, under floor heating (only in the children’s section) and hot water radiators. It is cooled by the air conditioning units. The radiators and the under floor heating are turned off during summer. The library has its own HVAC system mainly for cooling and ventilation therefore; a separate energy balance for this particular end‐use is carried out as shown in Figure 3 and Appendix B.1. Pumps There are 4 main pumps which provide heating and ventilation throughout the various spaces of the building. They include: P1‐ Primary Pump, P2‐ Heating System, P3‐ Ventilation Plant and P4‐ Heating System. During the site visit, Amp readings were measured to examine whether they were operating or not. The Amp readings are as follows: P1‐ 5.1 amps, P2‐ 2.7 amps, P3‐ 2.9 amps and P4‐ 2.4 amps. 15
Air Handling Units AHU1 – Air Handling Unit 1: This supplies one of the exhibit areas within the museum. Fresh and recycled air comes into the air handling unit which is heated by a hot water or cooled by a chilled water system. There is a humidifier attached to add humidity if required and also, an electric reheat. The target temperature is 20°C and 50‐60% relative humidity. If humidity levels are high then cooling will lower the humidity and the electric reheat brings the temperature up. The unit runs 24 hrs per day, 365 days per year. If outside temperature exceeds 15°C then the hot water heating does not work. During the occupied hours, the mixture of fresh and recycle air is varied based on the internal and external conditions. A minimum of 33% fresh air is introduced. When unoccupied, the system goes to 100% recycle. During the site visit, the amp reading for this unit was measured to be 4.1 amps. AHU2‐ Air Handling Unit 2: This supplies exhibition galleries and the foyer space. Fresh and recycled air comes into the air handling unit which is heated by a hot water radiator. A new humidifier is attached to add humidity control if required. The target temperature is 20°C and 50‐60% relative humidity. If outside temperature exceeds 15°C then the hot water heating does not work. Fresh air ranges from 33% to 100%. It is at 50% if the outside temperature is below 15°C and 100% when outside temperature is between 18°C ‐ 20°C and at 33% when outside temperature is at 23°C. During the site visit, the amp reading for this unit was measured to be 5.4 amps. AHU3‐ Air Handling Unit 3: This supplies the artifacts room within the museum which requires very stable conditions. Recycled air comes into the unit and is heated, cooled, dehumidified or humidified. Target temperatures are between 16°C ‐ 20°C and 50‐60% rh. During the site visit, the amp reading for this unit was measured to be 4.4 amps. 16
AHU4‐ Air Handling Unit 4: This supplies the performance area and has 100% fresh air which is heated to 20°C. The performance space has an extract fan removing air to the outside. This particular system operates based on time set in the BMS. If the outside temperature is above 15°C, then the hot water heating will not work. If the internal temperature exceeds 22°C when outside temperature is above 18°C, then the AHU supply fan and the room extract fan will both switch to high speed. This system does not have any cooling thus; cooling is not available in the performance space. During the site visit, the amp reading for this unit was measured to be 3.5 amps. A schematic diagram of how the system works is in Appendix C. 3.2: Space Heating A single 500kW gas‐burning boiler producers hot water for radiator heating and provides pre heat for the air handling units. Heating is available twelve months of the year and is controlled by the Building Management System (BMS). There are also, three hot water cylinders installed to provide hot water for the offices and the public toilets. The only end‐use of gas is for space heating from the boiler. Gas consumption has been calculated at about 406,656 kWh/yr costing almost $14,689/yr. During the visit in the boiler room, the surface temperature of the boiler was measured to be 31°C and room temperature was measured to be 27°C. It seemed very unpleasant and hot. When moving around to the various spaces of the building, variations in temperatures were felt. In the library, it was quite pleasant, warm and comfortable with the average temperature being about 23°C. However, in the museum spaces, variations were found. Some of the spaces felt warm and some felt quite cold. Temperatures ranged between 15°C ‐23°C. This was probably due to the HVAC system not working properly. 17
3.3: Lighting Various types of lamps are present in the Pataka building. The library and the offices mainly consist of T8 fluorescent lamps in a triple light fitting. The library also, consists of several focal floodlights with tungsten halogen lamps in order to enhance some of the spaces within the area. The museum consists of several different lamps in order to provide a range of variety for their exhibits. The lamps include: spotlights, wall washers, focal floodlights and down lights all with low voltage halogen lamps. A light track in each of the gallery spaces provides easy installation for the light fittings. The types of lamps and luminaires in use are provided in the energy balance calculation (Appendix B) for each major area, as well as when each area is used. The building generally is very well lit, with illumination (lux) levels well above the recommended level. For reference, the standard illumination levels from NZS 6703:1984 are listed in the table below:
Area Library ‐ By bookshelves Library ‐ By work desks Museum Foyer Space Performance Space Café
Measured Average Lux Fraction of Recommended Recommended Lux Level 750 150% 500 1700 340% 500 180 1800% 10 1520 1520% 100 780 156% 500 850 850% 100
Table 4: Standard illumination levels
As can be seen, the spaces are highly lit in all of the spaces. This is generally due to the effects of natural light. The working area within the library, the foyer space and the café are all daylit spaces however; artificial lighting is still used to illuminate these spaces. This is one of the issues which could be improved in order to save energy. Further discussion can be read in the Recommendations section pg. 23. The museum does not have a recommended lux level as it 18
depends on the various exhibits however; a minimum of 10 lux is needed for people to walk around. The lighting densities for each major area are listed in Table 5 below. Area Library ‐ By bookshelves Library ‐ By work desks Museum Foyer Space Performance Space Café
Lighting Load (kW) Net Floor Area (m2) Lighting Density (W/m2) 21 1500 14.0 3.6 220 16.4 15 1600 9.4 1.2 600 2.0 13.2 1300 10.2 1 300 3.3
Table 5: Lighting Densities
As can be seen, the Library is the most energy intensive area however; most of the other spaces do not need lighting as they are well daylit spaces. In this case, the use of natural light is well used but while observing the spaces particularly the foyer space, although it was a bright sunny day, the lights were still turned on and when I asked one of the staff members, he simply said that they forgot to turn them off. The lighting power density limit is generally between 11‐12 W/m2 therefore; many of these areas are less lit however; the library is lit well. The foyer space and the café do not need much artificial lighting as it is daylit and as a result, the lighting densities for these spaces are low. The performance space needs a bit improvement however; this space also depends on the type of performance being carried out. Generally, none of the lights in and out of the building are turned on after working hours however; security lights in the foyer space which include T8 fluorescent lamps are left on. 19
3.4: Other Electrical End‐Uses Other electrical end‐uses make up the whole distribution of energy end uses of the building. This includes: Office Equipment (1%), Other Equipment (5%) and Kitchen Equipment (1%). These end‐uses are very small and do not have a great potential for energy savings. Office Equipment includes: computers, printers and photocopiers. They are all switched off after working hours to reduce energy consumption. The computers are all new with LCD screens which provide the benefits of energy efficiency. Other Equipment includes: warm air curtains, sewing machines, security cameras, hand dryers and a fish tank. The warm air curtains consume most of the energy as they operate 24 hrs a day, 365 days a year. Also, the security cameras operate everyday however; this is a necessity for the building owners. Kitchen Equipment includes: toasters, chill water unit, fridges, microwaves, stove and dishwasher. These do not consume much of the overall energy however; the fridges should be carefully monitored. Older fridges are not very efficient thus; increasing the energy consumption. Also, the dishwasher should only operate when it is completely full to minimize hot water usage. 20
4: Energy Management 4.1: Monitoring and Targeting The Pataka building is controlled by a Building Management System (BMS) which is monitored by Aquaheat. They provide the services which allows them to check on the settings remotely and respond to alarm conditions. The system is setup to provide a strong focus on energy efficiency if it works correctly. During the past few months, there have been a few issues with new equipment installed and lack of response to room control in the artifacts room. Monthly gas and electricity invoices are kept and managed by Energy and Technical Services (ETS). They also, record gas and electricity use in order to provide details on energy management including its operation, efficiency and cost. All the data collected is recorded into a website: http://www.e‐bench.com/eBench/index.jsp which can be viewed by the facilities manager of the Pataka building. ETS monitor the energy and compare it to other industry benchmarks or the energy use of previous years. 4.2: Investment The Pataka building is relatively new and thus there has not been a need for major investment in the mechanical services of the building. However to improve efficiency, a new humidifier and an air conditioner has been installed. 4.3: Policy There is no formal energy policy however; the management of the system has been designed in order to provide improvements through other delegated companies such as ETS and Aquaheat. Level 2 Energy Audits are also done for the building by Smart Power in order to provide further assessments and analysis. 21
4.4: Technical The equipment is in good condition however some of the equipments have not been working correctly. The maintenance program is planned and in place which provides details on issues regarding the plant. During the recent maintenance check it was found that: ‐ The new AHU2 humidifier set points were very tight, between 47‐49%. ‐ AHU1 humidifier was drawing current but was not producing any steam. ‐ AHU3 humidifier seemed faulty and needs to be replaced.
In general, the building is well managed and has an incentive to be energy efficient. 22
5: Recommendations The Pataka building is well managed and has a sufficient BMS in order to provide energy efficiency measures. It has various companies monitoring its services to control efficiency and improve standards. The recommendations provided below are from the various observations being made. These recommendations need to be further investigated and assessed in order to provide potential energy savings in dollar terms. ‐ In the library where work desks are placed, the space is very well lit by natural light. During sunny days, direct sunlight penetrates through the north facing glazed façade. The light levels in this space are extremely high (1200‐2000 lux) and therefore; artificial lighting is not needed during a sunny day. From the several site visits observed during a sunny day, the lighting was turned on which did not have any effect as direct light was streaming into the space. The lighting in this area consists of approximately 55 T8 fluorescent lamps with a wattage output of 58W. These could all be turned off by a single switch during a sunny day when direct sunlight penetrates through the glazed façade all day long. Potential savings could be made thus; reducing the energy use. Also, daylight can be controlled all day through the venetian blinds to increase the intensity of light entering the space and reducing glare effects in some of the areas. ‐ In the pacific and the magazine section, there are indoor flood lights with tungsten halogen lamps mounted on the ceiling. These floodlights are positioned to direct light onto the wall surface. It does not provide any light to the work desks and the shelves. They are kept on for no particular reason and as a result, they should be turned off or positioned in a way to enhance the architectural experience of the space, if that is the motive. The floodlights seem pointless and do not provide any benefits. Simply turning them off could have a huge impact on the annual energy costs. 23
‐ The library consists of a substantial amount of 58W T8 fluorescent lamps. These could be replaced by energy saving fluorescents. There is a new product in the market by Philips called the Mater TL‐D Eco lamps which would provide a number of benefits. This includes: savings of more than 10% and reduction in CO2 emissions. A 51W Master TL‐D Eco lamp can provide the same number of lumens in a 58W fluorescent lamp thus; reducing energy costs. Further information on this product can be found in Appendix D. All the fluorescent lamps in the building should be replaced by this particular lamp in order to reduce energy costs. ‐ The foyer space is also, very well daylit and does not need any artificial lighting during the day. When observed during a sunny day, the lighting was turned on which did not make any sense therefore; a staff member was interviewed in order to provide details on this situation. The staff member simply had no explanation and said that they forgot to turn them off. As a result, simple measures should be taken in order to minimize mistakes which could potentially increase energy use. The lights could be on a timer which could automatically switch them off. ‐ Museum lighting varies quite a lot depending on the exhibits. The types of lamps used in the different luminaires appeared to be the same. The lamps used are mostly standard low‐ wattage dichroic halogen lamps. These should be replaced by the new Philips MATERLine ES halogen lamps. The benefits include: savings of more than 30% on energy costs, less carbon emissions and more lamp life. Also, a 45W MATERLine ES can provide up to 80% more light than a standard 50W dichroic lamp. Further information on this product can be found in Appendix D. ‐ The museum uses the most of the electrical energy compared to the rest of the areas in the building. It uses 55% of the total electricity consumption which is substantial compared to the other areas of the building, as shown in Figure 11 pg. 10. The museum is not used as much as the library however; it consumes the most of the electricity. This is due to the various precautions being made in order to keep all the paintings and sculptures safe and secure. Humidifiers and the HVAC system work 24 hours a day 365 days a year in order to 24
prevent damage and provide comfort. However, it is recommended that further assessments should be taken as to why the museum is consuming so much energy. ‐ During the recent maintenance check it was found that the new AHU2 humidifier set points were very tight, between 47‐49%. If the gallery humidity control can be relaxed, then significant savings could be made as the humidifier is currently running at 100% all the time. ‐ One of the humidifiers was drawing current but was not producing any steam. This should be turned off until repaired. ‐ Services should be regularly maintained and repaired as soon as possible. ‐ The BMS needs to be properly configured, monitored and maintained for different seasons in order to provide comfort and reduce energy use however, this needs further investigation. ‐ The Pataka building has a negotiated contract for electricity purchase with Meridian Energy. On contract renewal, spot market prices should be considered which could save annual costs. 25
Appendix A: Energy Purchase Records and Pricing Details A.1: Electricity Purchases Electricity invoices for the Pataka building were collected from the website provided by ETS and recorded into a spreadsheet showing consumption and cost as shown in Table 6 below: Electricity Consumption and Prices Consumption 2007 (kWh) 2007 ($) exc GST Average Price (c/kWh) January 46,854.66 5,268.09 11.24 February 47,302.64 6,034.07 12.76 March 58,422.80 7,628.32 13.06 April 52,454.40 6,412.25 12.22 May 55,373.92 7,350.65 13.27 June 54,504.38 7,937.66 14.56 July 56,967.90 8,074.33 14.17 August 58,230.18 8,132.59 13.97 September 53,832.44 6,778.59 12.59 October 53,592.10 6,483.32 12.10 November 53,124.66 5,560.71 10.47 December 59,348.36 5,858.85 9.87 TOTAL 650,008.44 81,519.43 12.54 Average 54167.37 6793.29 12.52
Table 6: Electricity Consumption and Prices
From the given data, Average Price (c/kWh) including energy and fixed charge was calculated for the year and for each month. The invoice is for the year ending 2007. Table 7 and 8 below shows electricity cost and consumption for years 2005‐2007. This was used for the daily graphs and percentage increase in electricity. 26
Electricity Costs for years 2005‐2007
2007
2006
2005
January
5,268
5,303
4,838
February
6,034
6,903
5,709
March
7,628
7,354
6,249
April
6,412
6,612
5,639
May
7,351
7,674
6,108
June
7,938
8,235
6,401
July
8,074
7,998
6,233
August
8,133
8,097
6,355
September
6,779
6,901
5,728
October
6,483
6,806
5,599
November
5,561
5,957
5,133
December
5,859
5,128
5,192
81,519
82,968
69,183
Running Total
Table 7: Electricity Costs for years 2005‐2007
Electricity Consumption Comparison (kWh)
2007
2006
2005
January
46,855
56,048
52,943
February
47,303
57,512
53,972
March
58,423
55,446
57,240
April
52,454
48,793
49,794
May
55,374
53,539
50,945
June
54,504
52,191
48,830
July
56,968
52,632
49,465
August
58,230
52,417
50,047
September
53,832
50,670
48,845
October
53,592
51,907
50,455
November
53,125
52,886
53,728
December
59,348
47,337
57,850
Running Total
650,008
631,378
624,114
Table 8: Electricity Consumption Comparison
A.2: Electricity Tariffs The Pataka Building is currently supplied electricity from Meridian Energy. They have a three year contract which 100% is fixed, though the rates vary for different times of the day, weekday to weekend day and month to month as explained in Section 2.4 27
The pricing details are based on the July 2007 electricity invoice. The time of use pricing structure is as follows (all prices exclude GST):
Time of Use
From
To
Rate ($/kWh)
Losses
Non Business Day
0:00
4:00
0.0867
1.028
Non Business Day
4:00
8:00
0.0621
1.028
Non Business Day
8:00
12:00
0.0888
1.028
Non Business Day
12:00
16:00
0.0789
1.028
Non Business Day
16:00
20:00
0.1115
1.028
Non Business Day
20:00
24:00
0.0867
1.028
Business Day
0:00
4:00
0.0824
1.028
Business Day
4:00
8:00
0.0958
1.028
Business Day
8:00
12:00
0.1266
1.028
Business Day
12:00
16:00
0.109
1.028
Business Day
16:00
20:00
0.1354
1.028
Business Day
20:00
24:00
0.1107
1.028
Table 9: Time of Use Electricity Pricing Structure
A.3: Breakdown of Annual Electricity Consumption by Area The graph for the breakdown of annual electricity use by area was provided by the library manager, who records the data into a spreadsheet. The data is from the various sub meters installed. Table 10 below shows the data given:
Jan‐07 Feb‐07 Mar‐07 Apr‐07 May‐07 Jun‐07 Jul‐07 Aug‐07 Sep‐07 Oct‐07 Nov‐07 Dec‐07 Total
Café 5,134 2,746 4,133 5,486 3,714 3,687 5,685 4,760 2,612 4,373 4,174 3,253 49,757
Dance 3,073 1,965 2,969 3,855 2,616 3,390 3,772 4,346 1,272 3,221 3,619 2,141 36,239
Library 20,584 11,328 16,760 21,824 14,064 14,728 22,232 23,064 7,440 17,152 17,976 18,032 205,184
Museum 18,064 31,262 34,607 21,289 35,006 32,718 25,303 26,083 42,439 28,880 27,350 35,915 358,916
Table 10: Data from sub meters
28
A.4: Gas Purchase Gas invoices for the Pataka building were collected from the website provided by ETS and recorded into a spreadsheet showing consumption and cost as shown in Table 11 below: Gas Consumption and Prices
Consumption (kWh)
2007 ($) exc GST
Average Price (c/kWh)
January
5,368.34
193.07
3.60
February
5,310.66
190.96
3.60
March
7,453.90
267.87
3.59
April
23,134.58
830.23
3.59
May
32,064.46
1,150.50
3.59
June
59,636.98
2,139.81
3.59
July
71,696.86
2,572.42
3.59
August
54,578.33
1,958.38
3.59
September
41,491.12
1,488.93
3.59
October
52,362.19
1,926.02
3.68
November
29,289.61
1,077.64
3.68
December
24,268.89
893.05
3.68
Running Total
406,655.91
14,688.88
3.61
Average
33,887.99
1,224.07
3.61
Table 10: Gas Consumption and Prices From the given data, Average Price (c/kWh) including energy and fixed charge was calculated for the year and for each month. The invoice is for the year ending 2007. Table 11 and 12 below shows gas consumption and costs for years 2005‐2007. This was used for the daily graphs and percentage increase and decrease in gas consumption. 29
Gas Consumption Comparison
2007
2006
2005
January
5,368
‐
26,959
February
5,311
1,185
3,714
March
7,454
36,260
6,707
April
23,135
25,979
44,323
May
32,064
45,602
48,155
June
59,637
76,764
78,270
July
71,697
80,235
65,204
August
54,578
62,659
62,345
September
41,491
46,200
56,486
October
52,362
49,257
38,822
November
29,290
25,637
22,970
December
24,269
27,556
1,644
Running Total
406,656
477,333
455,598
Table 11: Gas Consumption Comparison
Gas Cost Comparison
2007
2006
2005
January
193
0
844
February
191
38
116
March
268
1,199
210
April
830
859
1,587
May
1,150
1,508
1,724
June
2,140
2,539
2,458
July
2,572
2,637
2,047
August
1,958
2,060
1,958
September
1,489
1,519
1,824
October
1,926
1,767
1,284
November
1,078
920
760
December
893
989
54
Running Total
14,689
16,036
14,866
Table 12: Gas Cost Comparison
30
Appendix B: Energy Balance The spreadsheet for the energy end use graph is recorded below: Table 13: Calculated Energy Balance
31
All the information for the energy balance was gathered from observations and documents received by the building owners and companies monitoring the energy management of the building. B.1: Calculation for Library HVAC To calculate the library HVAC the information from its sub meter was used. The Library has its own cooling and ventilation but does not include heating as it comes from the main plant. Electricity in the library is used for: Lighting, kitchen equipment, office equipment and fans. As a result, an energy balance for just the library was carried out to determine the HVAC use. Table 14 and 15 below summarizes the calculation being made.
kW
Utilisation
Hours/day
Weeks per year
kW
fluorescents
0.06
520
31.2
95%
12
7
52
0.1
20
2
95%
12
7
52
floodlights
Quantity
Days per week
Lighting for Library
Lighting Total Kitchen equipment (From Total Energy Balance) office equipment
pc Printers and photocopiers
0.1 0.02
Office Equipment Total
fans
40 10
1
Sub TOTAL
4 0.2
4
60% 20%
4
10 10
15%
5 5
24
50 50
7
52
kWh pa 129,467.52 8,299.20 137,767 10,000 6,000 100 6,100 5,242 159,108
Table 14: Library Energy Balance
Total Energy Consumption from library sub meter (Appendix A.3)
205,184.00
Estimated Energy from other sources
159,108.00
Therefore: Library HVAC
46,076.00
Table 15: Library HVAC calculation
32
Appendix C: Schematic of the plant
33
Appendix D: Product Information
Product brochures which show information on potential energy savings. Further information can be found on: www.philips.com/eco
34
01
1: Introduction
02
2: Historical Energy Consumption
03
2.1: Gas Purchase History
04
2.2: Electricity Purchase History
05
2.3: Energy Use Index
11
2.4: Tariff Analysis
11
3: Energy end‐uses
14
3.1: Summary of HVAC operation
15
3.2: Space Heating
17
3.3: Lighting
18
3.4: Other Electrical End‐Uses
20
4: Energy Management
21
4.1: Monitoring and Targeting
21
4.2: Investment
21
4.3: Policy
21
4.4: Technical
22
5: Recommendations
23
Appendix A: Energy Purchase Records and Pricing Details
26
Appendix B: Energy Balance
31
Appendix C: Schematic of the plant
33
Appendix D: Product Information
34
Executive Summary This report documents the savings opportunities and assesses the energy consumption found during the energy audit of the Pataka Building situated in Porirua, Wellington. Total annual energy use is shown below: Energy Source Natural Gas Electric Energy Total
Annual Usage (kWh/yr) 406,656 650,008
Average Price (c/kWh)
Annual Cost ($) 3.61 (energy + fixed charges) 14,689 12.54 (energy + fixed charges) 81,519 1,056,664 9.10 96,208 Table 1: Annual Energy Use
The price that the building pays for natural gas is about what one would expect however; for electricity savings could be made after the negotiated contract is over. The energy use index (EUI) for the Pataka building is 176 kWh/m2yr (as calculated in section 2.3). This is below the typical figure for commercial buildings in New Zealand, which generally use about 200 kWh/m2yr. As the library and the museum use the most energy, the EUI for just those particular areas is about 278 kWh/m2yr, which is higher than the benchmark. The distribution of energy by end‐use is shown in the pie chart below.
Figure 1: Distribution of Energy Use by End‐Use
Recommendations are documented through the observations being made which include: ‐ Turning unnecessary lights off and using natural light efficiently. ‐ Replacing existing lights with eco energy efficiency lights. ‐ Maintaining services regularly and repairing damage as soon as possible. 1
1: Introduction This report describes the energy consumption and savings opportunities for the Pataka Building located at Paramoana Street, Porirua. The Pataka building consists of a library, a museum, a performance space, a foyer space and a café, all contributing to the annual energy use of the building. The building is owned by the Porirua City Council and therefore; is a building for the people of Porirua City and the general public. It provides recreational and leisure activities for the general public and a place to experience the art and the culture of Porirua City. The walk through of the building services took place on 24 March 2008 with subsequent daytime visits till date. Observations and measurements were carried out to assess the current situation and provide recommendations based on the assessments. The building covers two levels and has a floor area of approximately 6014m2. It consists of materials that provide potential for thermal mass and has an exposed northern façade and a roof top which catches full sun and provides sufficient daylighting into the library and the foyer space. This also, provides substantial solar gain into the spaces creating over heating issues during summer but comfort during winter. The main finding of the audit is that the energy consumption of the building has increased compared to previous years. This could be caused by the services not running properly. The BMS needs to be properly configured and maintained for different seasons in order to provide comfort and reduce energy use. There are many opportunities to reduce the energy usage at low or no cost. The building poses some interesting challenges in energy management as it comprises of different usage of spaces within the fabric of the building. It consists of different spaces which have their own individual needs to provide comfort.
2
2: Historical Energy Consumption The Pataka Building in Porirua, Wellington uses both natural gas and electricity as its sources of purchased energy. The annual energy use and cost (excluding GST) from the available data (as shown in Appendix A) is summarized in Table 2 below. Energy Source Natural Gas Electric Energy Total
Annual Usage (kWh/yr) 406,656 650,008 1,056,664
Average Price (c/kWh)
Annual Cost ($) 3.61 (energy + fixed charges) 14,689 12.54 (energy + fixed charges) 81,519 9.10 96,208
Table 2: Annual Energy Consumption
Annual electricity and gas use is based on the consumption from 1 January 2007 to 31 December 2007. The contribution of each energy source to both annual energy use and annual energy cost is shown in Figure 2 below.
Figure 2: Energy sources as a percentage of annual use (left) and annual cost (right)
3
2.1: Gas Purchase History Historic gas use is plotted in Figure 3 below, as the average kWh/day. The data for this graph is in Appendix A.4.
Figure 3: Average Daily Natural Gas Consumption from Jan 05‐Dec07
As expected, the gas use is significantly higher in winter than in summer. This is because all of the natural gas is used for space heating purpose and therefore; winter loads are much higher compared to summer loads. The annual gas usage is up by 4% from 2005‐2006 however, the gas usage from 2006‐2007 is down by 15%, as shown in Appendix A.4. This decrease could have caused, due to outside temperatures being higher and as a result, space heating is not needed as much. The annual daily gas consumption in 2006 and 2007 is plotted against outside temperatures as shown in Figure 4. This provides a much better understanding of gas use compared to outside temperature. The graph was taken from the e‐bench website which records daily climatic conditions and gas usage for the site. Gas use is highly seasonal, with average winter use being 1830 kWh/day, approximately 3‐4 times higher than the average summer use being 580 kWh/day. 4
Figure 4: Annual Daily Gas Consumption in 2006 and 2007 plotted against outside mean temperature
2.2: Electricity Purchase History Historic electricity use is plotted in Figure 5 below, as the average kWh/day. The data for this graph is in Appendix A.1. Figure 5: Average Daily Electricity Use from Jan 05‐Dec07
5
The graph shows a reverse seasonal pattern. Usually, electricity loads are higher in winter compared to summer however; for this case, the electrical energy is being used more in summer than winter. This is because the electricity is being used by the air conditioning units during summer for cooling and therefore; the loads are slightly higher during the summer months. The electricity usage from 2005‐2007 has remained quite constant. It has only increased by 4%. The average electricity use (approximately 1,708 kWh/day) would mostly be used for cooling, lighting and heating water. On the other hand, annual electricity cost has increased 17% over the same frame due to increased electricity charges. The daily cost of electricity has also increased significantly from 2005‐2006 but a slight increase from 2006‐07 as represented by Figure 6 below. Figure 6: Average daily cost of electricity use from 2005‐2007
The half‐hourly electricity use for February 2007 is plotted in Figures 7 and 8 below. These show the day‐to‐day and hour‐to‐hour patterns of electricity use during a summer month. 6
Figure 7: February 2007 Electricity Use
Figure 7 shows the electric energy use in the middle of summer. The point directly above the mark on the time axis represents midnight, and the space between the peaks, 24 hours. The daily patterns are quite consistent. Figure 8 shows the same data, but all the daily load patterns have been plotted on top of each other to establish an average load profile. This can therefore determine hour‐to‐hour trends as shown below. Figure 8: February 2007 Electricity Use – Average Daily Patterns
7
The solid bold black line represents the average weekday loads, whilst the dashed line represents the average weekend load. As can be seen, average electricity demand in the evening and the early morning is at its minimum of about 38kW. The rise in electricity use starts at about 8am and climbs to approximately 115kW during the midday period where it is at its peak. The load remains consistent after that however; it starts to decline slowly and then a significant drop as the demand for electricity reduces. This is because the main areas of the building which include the library and the museum close after 5.30pm and as a result, less electricity demand is needed. The graph for weekend use follows the same pattern however; less demand is used due to the less occupancy in the building. Offices and other management areas are closed therefore; less energy is consumed. Figures 9 and 10 represent the half‐hourly patterns of electricity use for July 2007. These show the day‐to‐day and hour‐to‐hour patterns of electricity use during a winter month.
Figure 9: July 2007 Electricity Use
8
Figure 9 shows the electric energy use in the middle of winter. The daily patterns are quite consistent and similar to the February patterns. The load variability remains consistent throughout the month and there is no significant peak or drop noticed compared to the February month. Figure 10 shows the same data, but all the daily load patterns have been plotted on top of each other to establish an average load profile for the winter month. This can therefore determine hour‐to‐hour trends as shown below.
Figure 10: July 2007 Electricity Use – Average Daily Patterns
As can be seen, average electricity demand in the evening and the early morning is at its minimum of about 50kW. The rise in electricity use starts at about 8am and climbs to approximately 125kW during the midday period where it is at its peak. The load starts to decline slowly and then a significant drop as the demand for electricity reduces. The graph for weekend use follows the same pattern however; the peak demand reaches at 125kW at approximately 11am and slowly drops as the day progresses. 9
From the established load profiles for February and July, it can be seen that energy demand increases during the winter month compared to the summer month. This is most possibly due to the heating pumps and humidifiers utilizing more energy during the winter month. The humidifiers would be operating more as the outside temperature and humidity affect the museum spaces. Also, there are three hot water cylinders which would increase the demand for electricity during the winter month. The breakdown of annual electricity consumption by area was also determined as shown in Figure 11 below. This data was established through the various sub meters which record electricity consumption by each area. The data was given by the Library manager who keeps records of the energy use by area (shown in Appendix A.3). Figure 11: Breakdown of Annual Electricity Consumption by Area within the Building
As can be seen, the museum consumes a substantial amount of electrical energy compared to the other areas of the building. This is quite unusual as the museum is less occupied than the library. However, services such as humidifiers are running all day throughout the whole year to provide comfort and prevent damage. Also, the artifacts room has to be well controlled in order to prevent damage. 10
2.3: Energy Use Index The energy use index (EUI) is the annual energy consumption of the building, divided by its floor area. The net area of the building is approximately 6014m2. The total annual energy consumption is approximately 1,056,664 kWh, consisting of 650,008 kWh of electricity and 406,656 kWh of gas. Therefore, the energy use index is: 1,056,664kWh/yr / 6014m2 = 176 kWh/m2.yr A typical EUI for commercial buildings is 200kWh/m2.yr of Net Lettable Area. 1 The EUI for the Pataka building is 176 kWh/m2.yr, which is slightly lower than the benchmark. As the library and the museum use the most energy, the annual energy use of the main areas can be carried out to determine the EUI for those particular areas of the building. The net area of the two main spaces is approximately 3796 m2 and therefore; the EUI can be calculated to be approximately 278 kWh/m2.yr, which is higher than the benchmark however; further investigation is needed to carry out an accurate EUI for the two main energy consuming areas of the building. 2.4: Tariff Analysis Electricity The electricity for the Pataka Building is supplied by Meridian Energy. Porirua City Council (PCC), the owners of the building have negotiated an electricity supply contract with Meridian Energy. The contract prices are 100% fixed for three years, though the rates vary for different times of the day, weekday to weekend day and month to month. The prices negotiated are in four hour blocks during business and non‐business day with higher prices during the time between 8am – 12 pm and 4pm – 8pm as shown in Appendix A.2. The prices are higher when the peak demand is high as shown in the load profile graphs (figures 8 and 10).
1
AS/NZS 4220: 1982 Energy Conservation in Non‐Residential Building, p.9
11
Over the past year the average electricity paid by PCC has been averaged 12.52 c/kWh inclusive of both energy and fixed charges. Each month has also, been calculated which can be viewed in Appendix A. Network services are provided by Vector Networks. The Pataka building has been on the G46 rate which is for sites with dedicated transformers greater than 300kVA. The G46 rate includes: ‐ A fixed rate of 0.0337 $/day ‐ anytime maximum demand rate of 8.0151 $/kVA/month – based on the single highest demand in each month – any time of the day ‐ coincident maximum demand rate of 3.3996 $/kVA/month – based on the single highest demand occurring between 7.30am and 9.30am, and 5.30pm and 7.30pm on weekdays (including public holidays). ‐ Capacity rate of 0.5223 $/KVA/month – based on the installed transformer capacity, in this case 300kVA. This particular rate was the best option for the Pataka building to be on however; new charges as at 1 April 2008 have been made which is shown below. ‐ A fixed rate of 16.4835 $/day ‐ Anytime maximum demand rate of 5.3476 $/kVA/month – based on the single highest demand in each month – any time of the day ‐ Capacity rate of 0.0137 $/KVA/month – based on the installed transformer capacity, in this case 300kVA. ‐ A variable charge is introduced at 0.58 c/kWh. These changes are shown below in Table 3. The new network charges are lower by $200 per month and there is less incentive to control the maximum demand.
Charge
2007/08‐ old ($)
2008/09 – new ($)
Daily AMD CMD Capacity Variable Total
0.337 8.0151 3.3996 0.5223 0
Cost March 08 ($)
16.4835 5.3476 0 0.0137 0.0058
10.5 1492 592 157 0 2252
Cost April 08 ($) 511 990 0 123 431 2055
Table 3: Comparison of old and new network charges
12
Gas Gas is supplied by Nova Gas. Over the past year the average electricity paid by PCC has been averaged 3.61 c/kWh inclusive of both energy and fixed charges. Each month has also, been calculated which can be viewed in Appendix A.4. Gas charges include: ‐ Consumption charge of 9.9614 $/GJ = 3.4 c/kWh ‐ Gas Industry Company Levy of 0.0178 $/GJ ‐ ICP Levy of 0.0173 $/day 13
3: Energy end‐uses The layout of the Pataka building is shown in Figure 12 below. Office spaces within the library and the museum are shaded. The void area is an outdoor open area mainly used by the café. The layout shows where each space is within the building and represents the spaces which consume the most energy apart from the void.
Figure 12: Layout of the Building
The Pataka building uses both natural gas and electricity. The gas is used for space heating and all the other end‐uses consume electricity. The estimated distribution of energy end‐uses on an annual basis is shown in Figure 13 below. Figure 13: Estimated Annual Distribution of Energy End‐uses
14
The energy distribution graph is determined from the energy balance carried out for the building, as described in Appendix B. As can be seen, space heating is the largest energy end‐ use, accounting for 39% of the total annual energy consumption. The second largest end‐use is the HVAC, which consumes 27% of the total energy. The lighting uses about 23% of the total energy and office equipment, other equipment, kitchen equipment and the Library HVAC make up the rest of the energy use. Each major end‐use is discussed separately, in the following section. 3.1: Summary of HVAC operation Library The library area is heated by air conditioning units, under floor heating (only in the children’s section) and hot water radiators. It is cooled by the air conditioning units. The radiators and the under floor heating are turned off during summer. The library has its own HVAC system mainly for cooling and ventilation therefore; a separate energy balance for this particular end‐use is carried out as shown in Figure 3 and Appendix B.1. Pumps There are 4 main pumps which provide heating and ventilation throughout the various spaces of the building. They include: P1‐ Primary Pump, P2‐ Heating System, P3‐ Ventilation Plant and P4‐ Heating System. During the site visit, Amp readings were measured to examine whether they were operating or not. The Amp readings are as follows: P1‐ 5.1 amps, P2‐ 2.7 amps, P3‐ 2.9 amps and P4‐ 2.4 amps. 15
Air Handling Units AHU1 – Air Handling Unit 1: This supplies one of the exhibit areas within the museum. Fresh and recycled air comes into the air handling unit which is heated by a hot water or cooled by a chilled water system. There is a humidifier attached to add humidity if required and also, an electric reheat. The target temperature is 20°C and 50‐60% relative humidity. If humidity levels are high then cooling will lower the humidity and the electric reheat brings the temperature up. The unit runs 24 hrs per day, 365 days per year. If outside temperature exceeds 15°C then the hot water heating does not work. During the occupied hours, the mixture of fresh and recycle air is varied based on the internal and external conditions. A minimum of 33% fresh air is introduced. When unoccupied, the system goes to 100% recycle. During the site visit, the amp reading for this unit was measured to be 4.1 amps. AHU2‐ Air Handling Unit 2: This supplies exhibition galleries and the foyer space. Fresh and recycled air comes into the air handling unit which is heated by a hot water radiator. A new humidifier is attached to add humidity control if required. The target temperature is 20°C and 50‐60% relative humidity. If outside temperature exceeds 15°C then the hot water heating does not work. Fresh air ranges from 33% to 100%. It is at 50% if the outside temperature is below 15°C and 100% when outside temperature is between 18°C ‐ 20°C and at 33% when outside temperature is at 23°C. During the site visit, the amp reading for this unit was measured to be 5.4 amps. AHU3‐ Air Handling Unit 3: This supplies the artifacts room within the museum which requires very stable conditions. Recycled air comes into the unit and is heated, cooled, dehumidified or humidified. Target temperatures are between 16°C ‐ 20°C and 50‐60% rh. During the site visit, the amp reading for this unit was measured to be 4.4 amps. 16
AHU4‐ Air Handling Unit 4: This supplies the performance area and has 100% fresh air which is heated to 20°C. The performance space has an extract fan removing air to the outside. This particular system operates based on time set in the BMS. If the outside temperature is above 15°C, then the hot water heating will not work. If the internal temperature exceeds 22°C when outside temperature is above 18°C, then the AHU supply fan and the room extract fan will both switch to high speed. This system does not have any cooling thus; cooling is not available in the performance space. During the site visit, the amp reading for this unit was measured to be 3.5 amps. A schematic diagram of how the system works is in Appendix C. 3.2: Space Heating A single 500kW gas‐burning boiler producers hot water for radiator heating and provides pre heat for the air handling units. Heating is available twelve months of the year and is controlled by the Building Management System (BMS). There are also, three hot water cylinders installed to provide hot water for the offices and the public toilets. The only end‐use of gas is for space heating from the boiler. Gas consumption has been calculated at about 406,656 kWh/yr costing almost $14,689/yr. During the visit in the boiler room, the surface temperature of the boiler was measured to be 31°C and room temperature was measured to be 27°C. It seemed very unpleasant and hot. When moving around to the various spaces of the building, variations in temperatures were felt. In the library, it was quite pleasant, warm and comfortable with the average temperature being about 23°C. However, in the museum spaces, variations were found. Some of the spaces felt warm and some felt quite cold. Temperatures ranged between 15°C ‐23°C. This was probably due to the HVAC system not working properly. 17
3.3: Lighting Various types of lamps are present in the Pataka building. The library and the offices mainly consist of T8 fluorescent lamps in a triple light fitting. The library also, consists of several focal floodlights with tungsten halogen lamps in order to enhance some of the spaces within the area. The museum consists of several different lamps in order to provide a range of variety for their exhibits. The lamps include: spotlights, wall washers, focal floodlights and down lights all with low voltage halogen lamps. A light track in each of the gallery spaces provides easy installation for the light fittings. The types of lamps and luminaires in use are provided in the energy balance calculation (Appendix B) for each major area, as well as when each area is used. The building generally is very well lit, with illumination (lux) levels well above the recommended level. For reference, the standard illumination levels from NZS 6703:1984 are listed in the table below:
Area Library ‐ By bookshelves Library ‐ By work desks Museum Foyer Space Performance Space Café
Measured Average Lux Fraction of Recommended Recommended Lux Level 750 150% 500 1700 340% 500 180 1800% 10 1520 1520% 100 780 156% 500 850 850% 100
Table 4: Standard illumination levels
As can be seen, the spaces are highly lit in all of the spaces. This is generally due to the effects of natural light. The working area within the library, the foyer space and the café are all daylit spaces however; artificial lighting is still used to illuminate these spaces. This is one of the issues which could be improved in order to save energy. Further discussion can be read in the Recommendations section pg. 23. The museum does not have a recommended lux level as it 18
depends on the various exhibits however; a minimum of 10 lux is needed for people to walk around. The lighting densities for each major area are listed in Table 5 below. Area Library ‐ By bookshelves Library ‐ By work desks Museum Foyer Space Performance Space Café
Lighting Load (kW) Net Floor Area (m2) Lighting Density (W/m2) 21 1500 14.0 3.6 220 16.4 15 1600 9.4 1.2 600 2.0 13.2 1300 10.2 1 300 3.3
Table 5: Lighting Densities
As can be seen, the Library is the most energy intensive area however; most of the other spaces do not need lighting as they are well daylit spaces. In this case, the use of natural light is well used but while observing the spaces particularly the foyer space, although it was a bright sunny day, the lights were still turned on and when I asked one of the staff members, he simply said that they forgot to turn them off. The lighting power density limit is generally between 11‐12 W/m2 therefore; many of these areas are less lit however; the library is lit well. The foyer space and the café do not need much artificial lighting as it is daylit and as a result, the lighting densities for these spaces are low. The performance space needs a bit improvement however; this space also depends on the type of performance being carried out. Generally, none of the lights in and out of the building are turned on after working hours however; security lights in the foyer space which include T8 fluorescent lamps are left on. 19
3.4: Other Electrical End‐Uses Other electrical end‐uses make up the whole distribution of energy end uses of the building. This includes: Office Equipment (1%), Other Equipment (5%) and Kitchen Equipment (1%). These end‐uses are very small and do not have a great potential for energy savings. Office Equipment includes: computers, printers and photocopiers. They are all switched off after working hours to reduce energy consumption. The computers are all new with LCD screens which provide the benefits of energy efficiency. Other Equipment includes: warm air curtains, sewing machines, security cameras, hand dryers and a fish tank. The warm air curtains consume most of the energy as they operate 24 hrs a day, 365 days a year. Also, the security cameras operate everyday however; this is a necessity for the building owners. Kitchen Equipment includes: toasters, chill water unit, fridges, microwaves, stove and dishwasher. These do not consume much of the overall energy however; the fridges should be carefully monitored. Older fridges are not very efficient thus; increasing the energy consumption. Also, the dishwasher should only operate when it is completely full to minimize hot water usage. 20
4: Energy Management 4.1: Monitoring and Targeting The Pataka building is controlled by a Building Management System (BMS) which is monitored by Aquaheat. They provide the services which allows them to check on the settings remotely and respond to alarm conditions. The system is setup to provide a strong focus on energy efficiency if it works correctly. During the past few months, there have been a few issues with new equipment installed and lack of response to room control in the artifacts room. Monthly gas and electricity invoices are kept and managed by Energy and Technical Services (ETS). They also, record gas and electricity use in order to provide details on energy management including its operation, efficiency and cost. All the data collected is recorded into a website: http://www.e‐bench.com/eBench/index.jsp which can be viewed by the facilities manager of the Pataka building. ETS monitor the energy and compare it to other industry benchmarks or the energy use of previous years. 4.2: Investment The Pataka building is relatively new and thus there has not been a need for major investment in the mechanical services of the building. However to improve efficiency, a new humidifier and an air conditioner has been installed. 4.3: Policy There is no formal energy policy however; the management of the system has been designed in order to provide improvements through other delegated companies such as ETS and Aquaheat. Level 2 Energy Audits are also done for the building by Smart Power in order to provide further assessments and analysis. 21
4.4: Technical The equipment is in good condition however some of the equipments have not been working correctly. The maintenance program is planned and in place which provides details on issues regarding the plant. During the recent maintenance check it was found that: ‐ The new AHU2 humidifier set points were very tight, between 47‐49%. ‐ AHU1 humidifier was drawing current but was not producing any steam. ‐ AHU3 humidifier seemed faulty and needs to be replaced.
In general, the building is well managed and has an incentive to be energy efficient. 22
5: Recommendations The Pataka building is well managed and has a sufficient BMS in order to provide energy efficiency measures. It has various companies monitoring its services to control efficiency and improve standards. The recommendations provided below are from the various observations being made. These recommendations need to be further investigated and assessed in order to provide potential energy savings in dollar terms. ‐ In the library where work desks are placed, the space is very well lit by natural light. During sunny days, direct sunlight penetrates through the north facing glazed façade. The light levels in this space are extremely high (1200‐2000 lux) and therefore; artificial lighting is not needed during a sunny day. From the several site visits observed during a sunny day, the lighting was turned on which did not have any effect as direct light was streaming into the space. The lighting in this area consists of approximately 55 T8 fluorescent lamps with a wattage output of 58W. These could all be turned off by a single switch during a sunny day when direct sunlight penetrates through the glazed façade all day long. Potential savings could be made thus; reducing the energy use. Also, daylight can be controlled all day through the venetian blinds to increase the intensity of light entering the space and reducing glare effects in some of the areas. ‐ In the pacific and the magazine section, there are indoor flood lights with tungsten halogen lamps mounted on the ceiling. These floodlights are positioned to direct light onto the wall surface. It does not provide any light to the work desks and the shelves. They are kept on for no particular reason and as a result, they should be turned off or positioned in a way to enhance the architectural experience of the space, if that is the motive. The floodlights seem pointless and do not provide any benefits. Simply turning them off could have a huge impact on the annual energy costs. 23
‐ The library consists of a substantial amount of 58W T8 fluorescent lamps. These could be replaced by energy saving fluorescents. There is a new product in the market by Philips called the Mater TL‐D Eco lamps which would provide a number of benefits. This includes: savings of more than 10% and reduction in CO2 emissions. A 51W Master TL‐D Eco lamp can provide the same number of lumens in a 58W fluorescent lamp thus; reducing energy costs. Further information on this product can be found in Appendix D. All the fluorescent lamps in the building should be replaced by this particular lamp in order to reduce energy costs. ‐ The foyer space is also, very well daylit and does not need any artificial lighting during the day. When observed during a sunny day, the lighting was turned on which did not make any sense therefore; a staff member was interviewed in order to provide details on this situation. The staff member simply had no explanation and said that they forgot to turn them off. As a result, simple measures should be taken in order to minimize mistakes which could potentially increase energy use. The lights could be on a timer which could automatically switch them off. ‐ Museum lighting varies quite a lot depending on the exhibits. The types of lamps used in the different luminaires appeared to be the same. The lamps used are mostly standard low‐ wattage dichroic halogen lamps. These should be replaced by the new Philips MATERLine ES halogen lamps. The benefits include: savings of more than 30% on energy costs, less carbon emissions and more lamp life. Also, a 45W MATERLine ES can provide up to 80% more light than a standard 50W dichroic lamp. Further information on this product can be found in Appendix D. ‐ The museum uses the most of the electrical energy compared to the rest of the areas in the building. It uses 55% of the total electricity consumption which is substantial compared to the other areas of the building, as shown in Figure 11 pg. 10. The museum is not used as much as the library however; it consumes the most of the electricity. This is due to the various precautions being made in order to keep all the paintings and sculptures safe and secure. Humidifiers and the HVAC system work 24 hours a day 365 days a year in order to 24
prevent damage and provide comfort. However, it is recommended that further assessments should be taken as to why the museum is consuming so much energy. ‐ During the recent maintenance check it was found that the new AHU2 humidifier set points were very tight, between 47‐49%. If the gallery humidity control can be relaxed, then significant savings could be made as the humidifier is currently running at 100% all the time. ‐ One of the humidifiers was drawing current but was not producing any steam. This should be turned off until repaired. ‐ Services should be regularly maintained and repaired as soon as possible. ‐ The BMS needs to be properly configured, monitored and maintained for different seasons in order to provide comfort and reduce energy use however, this needs further investigation. ‐ The Pataka building has a negotiated contract for electricity purchase with Meridian Energy. On contract renewal, spot market prices should be considered which could save annual costs. 25
Appendix A: Energy Purchase Records and Pricing Details A.1: Electricity Purchases Electricity invoices for the Pataka building were collected from the website provided by ETS and recorded into a spreadsheet showing consumption and cost as shown in Table 6 below: Electricity Consumption and Prices Consumption 2007 (kWh) 2007 ($) exc GST Average Price (c/kWh) January 46,854.66 5,268.09 11.24 February 47,302.64 6,034.07 12.76 March 58,422.80 7,628.32 13.06 April 52,454.40 6,412.25 12.22 May 55,373.92 7,350.65 13.27 June 54,504.38 7,937.66 14.56 July 56,967.90 8,074.33 14.17 August 58,230.18 8,132.59 13.97 September 53,832.44 6,778.59 12.59 October 53,592.10 6,483.32 12.10 November 53,124.66 5,560.71 10.47 December 59,348.36 5,858.85 9.87 TOTAL 650,008.44 81,519.43 12.54 Average 54167.37 6793.29 12.52
Table 6: Electricity Consumption and Prices
From the given data, Average Price (c/kWh) including energy and fixed charge was calculated for the year and for each month. The invoice is for the year ending 2007. Table 7 and 8 below shows electricity cost and consumption for years 2005‐2007. This was used for the daily graphs and percentage increase in electricity. 26
Electricity Costs for years 2005‐2007
2007
2006
2005
January
5,268
5,303
4,838
February
6,034
6,903
5,709
March
7,628
7,354
6,249
April
6,412
6,612
5,639
May
7,351
7,674
6,108
June
7,938
8,235
6,401
July
8,074
7,998
6,233
August
8,133
8,097
6,355
September
6,779
6,901
5,728
October
6,483
6,806
5,599
November
5,561
5,957
5,133
December
5,859
5,128
5,192
81,519
82,968
69,183
Running Total
Table 7: Electricity Costs for years 2005‐2007
Electricity Consumption Comparison (kWh)
2007
2006
2005
January
46,855
56,048
52,943
February
47,303
57,512
53,972
March
58,423
55,446
57,240
April
52,454
48,793
49,794
May
55,374
53,539
50,945
June
54,504
52,191
48,830
July
56,968
52,632
49,465
August
58,230
52,417
50,047
September
53,832
50,670
48,845
October
53,592
51,907
50,455
November
53,125
52,886
53,728
December
59,348
47,337
57,850
Running Total
650,008
631,378
624,114
Table 8: Electricity Consumption Comparison
A.2: Electricity Tariffs The Pataka Building is currently supplied electricity from Meridian Energy. They have a three year contract which 100% is fixed, though the rates vary for different times of the day, weekday to weekend day and month to month as explained in Section 2.4 27
The pricing details are based on the July 2007 electricity invoice. The time of use pricing structure is as follows (all prices exclude GST):
Time of Use
From
To
Rate ($/kWh)
Losses
Non Business Day
0:00
4:00
0.0867
1.028
Non Business Day
4:00
8:00
0.0621
1.028
Non Business Day
8:00
12:00
0.0888
1.028
Non Business Day
12:00
16:00
0.0789
1.028
Non Business Day
16:00
20:00
0.1115
1.028
Non Business Day
20:00
24:00
0.0867
1.028
Business Day
0:00
4:00
0.0824
1.028
Business Day
4:00
8:00
0.0958
1.028
Business Day
8:00
12:00
0.1266
1.028
Business Day
12:00
16:00
0.109
1.028
Business Day
16:00
20:00
0.1354
1.028
Business Day
20:00
24:00
0.1107
1.028
Table 9: Time of Use Electricity Pricing Structure
A.3: Breakdown of Annual Electricity Consumption by Area The graph for the breakdown of annual electricity use by area was provided by the library manager, who records the data into a spreadsheet. The data is from the various sub meters installed. Table 10 below shows the data given:
Jan‐07 Feb‐07 Mar‐07 Apr‐07 May‐07 Jun‐07 Jul‐07 Aug‐07 Sep‐07 Oct‐07 Nov‐07 Dec‐07 Total
Café 5,134 2,746 4,133 5,486 3,714 3,687 5,685 4,760 2,612 4,373 4,174 3,253 49,757
Dance 3,073 1,965 2,969 3,855 2,616 3,390 3,772 4,346 1,272 3,221 3,619 2,141 36,239
Library 20,584 11,328 16,760 21,824 14,064 14,728 22,232 23,064 7,440 17,152 17,976 18,032 205,184
Museum 18,064 31,262 34,607 21,289 35,006 32,718 25,303 26,083 42,439 28,880 27,350 35,915 358,916
Table 10: Data from sub meters
28
A.4: Gas Purchase Gas invoices for the Pataka building were collected from the website provided by ETS and recorded into a spreadsheet showing consumption and cost as shown in Table 11 below: Gas Consumption and Prices
Consumption (kWh)
2007 ($) exc GST
Average Price (c/kWh)
January
5,368.34
193.07
3.60
February
5,310.66
190.96
3.60
March
7,453.90
267.87
3.59
April
23,134.58
830.23
3.59
May
32,064.46
1,150.50
3.59
June
59,636.98
2,139.81
3.59
July
71,696.86
2,572.42
3.59
August
54,578.33
1,958.38
3.59
September
41,491.12
1,488.93
3.59
October
52,362.19
1,926.02
3.68
November
29,289.61
1,077.64
3.68
December
24,268.89
893.05
3.68
Running Total
406,655.91
14,688.88
3.61
Average
33,887.99
1,224.07
3.61
Table 10: Gas Consumption and Prices From the given data, Average Price (c/kWh) including energy and fixed charge was calculated for the year and for each month. The invoice is for the year ending 2007. Table 11 and 12 below shows gas consumption and costs for years 2005‐2007. This was used for the daily graphs and percentage increase and decrease in gas consumption. 29
Gas Consumption Comparison
2007
2006
2005
January
5,368
‐
26,959
February
5,311
1,185
3,714
March
7,454
36,260
6,707
April
23,135
25,979
44,323
May
32,064
45,602
48,155
June
59,637
76,764
78,270
July
71,697
80,235
65,204
August
54,578
62,659
62,345
September
41,491
46,200
56,486
October
52,362
49,257
38,822
November
29,290
25,637
22,970
December
24,269
27,556
1,644
Running Total
406,656
477,333
455,598
Table 11: Gas Consumption Comparison
Gas Cost Comparison
2007
2006
2005
January
193
0
844
February
191
38
116
March
268
1,199
210
April
830
859
1,587
May
1,150
1,508
1,724
June
2,140
2,539
2,458
July
2,572
2,637
2,047
August
1,958
2,060
1,958
September
1,489
1,519
1,824
October
1,926
1,767
1,284
November
1,078
920
760
December
893
989
54
Running Total
14,689
16,036
14,866
Table 12: Gas Cost Comparison
30
Appendix B: Energy Balance The spreadsheet for the energy end use graph is recorded below: Table 13: Calculated Energy Balance
31
All the information for the energy balance was gathered from observations and documents received by the building owners and companies monitoring the energy management of the building. B.1: Calculation for Library HVAC To calculate the library HVAC the information from its sub meter was used. The Library has its own cooling and ventilation but does not include heating as it comes from the main plant. Electricity in the library is used for: Lighting, kitchen equipment, office equipment and fans. As a result, an energy balance for just the library was carried out to determine the HVAC use. Table 14 and 15 below summarizes the calculation being made.
kW
Utilisation
Hours/day
Weeks per year
kW
fluorescents
0.06
520
31.2
95%
12
7
52
0.1
20
2
95%
12
7
52
floodlights
Quantity
Days per week
Lighting for Library
Lighting Total Kitchen equipment (From Total Energy Balance) office equipment
pc Printers and photocopiers
0.1 0.02
Office Equipment Total
fans
40 10
1
Sub TOTAL
4 0.2
4
60% 20%
4
10 10
15%
5 5
24
50 50
7
52
kWh pa 129,467.52 8,299.20 137,767 10,000 6,000 100 6,100 5,242 159,108
Table 14: Library Energy Balance
Total Energy Consumption from library sub meter (Appendix A.3)
205,184.00
Estimated Energy from other sources
159,108.00
Therefore: Library HVAC
46,076.00
Table 15: Library HVAC calculation
32
Appendix C: Schematic of the plant
33
Appendix D: Product Information
Product brochures which show information on potential energy savings. Further information can be found on: www.philips.com/eco
34
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