F-design Guidelines For Energy Effcient Building

DESIGN GUIDELINES FOR ENERGY EFFICIENT BUILDINGS

Architect Jiten Prajapati Mumbai September 2006

Contents ƒ Need for energy efficient buildings ? ƒ Design guidelines for two commercial buildings ƒ Warm and humid climate ƒ Hot and dry climate

Need for Energy Efficient Buildings ‰ User behaviour has changed ‰ Commercial buildings are huge consumers of energy ‰Average mall - Rs. 25 lakh/ month ‰Multistoreyed office - Rs. 15 lakh/ month ‰ Large potential for energy conservation ‰ Can lead to a thermally comfortable indoor environment ‰ Modern science has provided quantitative support

Example - a building without any chajja’s in Mumbai • No protection from rains and sunshine. • Has to be airconditioned and artificially lit • Manifold increase in consumption of energy e.g. Similar building pays Rs. 15 lacs as energy bill per month

What do we mean by energy efficient buildings? – Buildings that are comfortable for improving the productivity of occupants. • Understanding climate • Incorporation of passive solar techniques

– Consumption of conventional energy is reduced through appropriate design. • Understanding thermal performance of building design • Optimising design and operational parameters of the building

Warm and Humid Zone Multi-storeyed air conditioned office building

Energy Conservation Measures in the Design of a Commercial Building for Mumbai J. Prajapati and J. K. Nayak Energy Systems Engineering IIT Bombay, Powai, Mumbai - 400 076, India

Type of Building Studied TERR 7TH FLOOR

TERR

TERR

6TH FLOOR FC 5TH FLOOR GCW

4TH FLOOR 3RD FLOOR

LEGEND 2ND FLOOR

TERR = TERRACE FC

1ST FLOOR

= FALSE CEILING

GCW = GLASS CURTAIN WALL

GROUND FLOOR

GROUND LEVEL

BASEMENT

SECTION STAIRCASE L PANTRY

STORE STAIRCASE

L

LIFT LOBBY

STORE

L

TOILETS

TOILETS

GCW

N OFFICE HALL CABINS

GCW

NOTE: HATCHED PORTION INDICATES AIR-CONDITIONED AREA

CABINS

TYPICAL FLOOR PLAN

GCW

• Fully glazed south facade • Air-conditioned and artificially lit • Built-up Area = 7074 sqm • Conditioned Area = 5400 sqm • Ground + seven storeyed RCC structure

Analysis of climate

Performance of Building 800.00

Cooling 700.00

Energy Demand (GJ/month)

Heating

600.00 500.00 400.00 300.00 200.00 100.00 0.00 JAN

FEB

MAR

APR

MAY

JUN

JUL

AUG

SEP

Month

Annual Load = 6384 GJ Note: Only cooling load in Mumbai (no heating load)

OCT

NOV

DEC

Component-wise thermal gains Surface

Percentage

100% 80%

Internal Convective

60%

Air exchange

40% 20% 0% -20% JAN

FEB

MAR APR MAY

JUN

JUL

month

AUG

SEP

OCT NOV

DEC

Studies to Improve Building Performance PARAMETERS INVESTIGATED Glazing Size Glazing Type Orientation (longer axis) Shading Colour of External Surfaces Wall Type Air Change Rate Internal Gain Scheduling of air changes Setpoint for heating and cooling

Studies to Improve Building Performance Effect of Glazing Size 6500

Annu al Load (GJ)

6000 5500 5000 4500 4000 BASECASE

GLAZING SIZE BASECASE (Full ht. glass) (restricted to 1.2m height)

GLAZING SIZE (restricted to 1.2m

(% saving) N.A. 6.5

Studies to Improve Building Performance Effect of Glazing Type 7000

6000 5500 5000 4500

GLAZING TYPE BASECASE (single reflective coated) Single clear Double clear Double low-E Double reflective coated

Double reflective coated

Double low-E

Double clear

Single clear

4000 BASECASE

Annu al Load (GJ)

6500

(% saving) N.A. -9.3 -6.9 -0.9 2.2

Studies to Improve Building Performance Effect of Orientation

Annu al Load (GJ)

6500 6000 5500 5000 4500 4000 BASECASE

N-S

ORIENTATION (longer axis) BASECASE (NW-SE) N-S NE-SW E-W

NE-SW

E-W

(% saving) N.A. 6 7.7 2.1

Studies to Improve Building Performance Effect of Shading 6500

Annu al Load (GJ)

6000 5500 5000 4500 4000 BASECASE

10%

SHADING BASECASE (No shading) 10% 20% 50%

20%

50%

(% saving) N.A. 1.7 3.4 8.5

Studies to Improve Building Performance Effect of Colour

Annu al Load (GJ)

7000 6500 6000 5500 5000 4500 4000 BASECASE

dark grey

COLOUR OF EXT.SURFACE BASECASE (White) dark grey WALL TYPE BASECASE (Concrete block wall) ACCB (e.g. Siporex)

Effect of Wall type

Annu al Load (GJ)

6500 6000 5500 5000 4500 4000 BASECASE

ACCB

(% saving) N.A. -4 (% saving) N.A. 2.4

Studies to Improve Building Performance Effect of Air changes

Annu al Load (GJ)

7500 7000 6500 6000 5500 5000 4500 4000 BASECASE

0.5

2

4

ACH

AIR CHANGE RATE BASECASE (1.0 ach) 0.5 2 4

(% saving) N.A. 1.7 -3.5 -10.8

Studies to Improve Building Performance OTHER PARAMETERS INTERNAL GAIN BASECASE (100%) 10% 50% No internal gain

(% saving)

SCHEDULING OF AIR CHANGES SETPOINT BASECASE (21 °C - 24 °C) ( 20 °C - 25 °C)

1.4 (% saving) N.A. 7.1

N.A. 51.6 29.1 57.1

Comparison Between Improved and Basecase Building 7000

Annu al Load (GJ)

6000 5000 4000 3000 2000 1000 0 BASECASE

BASECASE IMPROVED

IMPROVED

Annual Load % saving (GJ) 6384 N.A. 4903 23

Conclusions – Part 1 • Cooling load predominant in Mumbai • Internal gains and external surfaces main contributors to heat gain • Effect of various parameters studied • Savings of 23% of annual loads can be achieved by optimising building design

Acknowledgement: We are grateful to Solar Energy Centre, Ministry of Non-conventional Energy Sources for sponsoring the project

Hot and Dry Zone Low-rise passive cooled office building

Passive Downdraft Evaporative Cooling (PDEC) System Inspector General of Police (I.G.P.) Complex, Gulbarga

Client:

Karnataka State Police Housing Corporation Architects: KEMBHAVI ARCHITECTURE FOUNDATION

ƒIdentification of Climatic Zone ƒAnalysis of Climate

ƒAnalysis of Building Design ƒIndoor Temperature ƒCooling Loads

ƒPassive Technique Passive Downdraft Evaporative Cooling Tower

ƒImplications of Design

Climatic Zones of India • • • • • •

HOT & DRY WARM & HUMID MODERATE COMPOSITE COLD & SUNNY COLD & CLOUDY

Gulbarga

Bio-climatic Chart COMFORTMAY ZONE

APR MAR

JAN

Inside Temperature of a Typical Room comfort fraction 40.00 38.00 36.00

32.00 30.00 28.00 26.00 24.00 22.00

6.00

4.00

2.00

24.00

22.00

20.00

18.00

16.00

14.00

12.00

10.00

20.00 8.00

temperature deg C

34.00

tim e hrs

toa oC tn +2.2 (upper comfort lim) tia oC

tn oC tn -2.2 (lower comfort lim)

Cooling Loads - Typical Room VENTILATION 19%

WALLS 4% ROOF 29%

WALLS ROOF GLAZING INTERNAL LOADS

GLAZING 14% INTERNAL LOADS 34%

VENTILATION LOADS

Design of PDEC System • Ambient hot-dry air is trapped, cooled by evaporation of water and then introduced in the building. • Simple system based on shower spray system developed by B. Givoni • Cost = 17.5 lakhs • Area cooled = 1100sqm. • Estimated Performance in May : – Outside air temperature = 38 °C – Temperature of air = 25 °C (at exit of tower) • About 4 - 10 air changes per hour Note: Approximate cost and area

CROSS BAFFLE WALL TO DIVERT WIND INTO TOWER

INLET OF TOWER WATER SPRINKLER TO COOL AIR BY EVAPORATION

TERRACE FLOOR

WOOD CHARCOAL LAYER TO FILTER OUT DUST AND INSECTS BAFFLE TO DIVERT AIR FLOW TO DIFFERENT ROOMS

FIRST FLOOR

GROUND FLOOR

COOL AIR EXITING FROM PDEC TOWER

WATER COLLECTED IN DRAIN FOR RE-CIRCULATION

Estimated performance of PDEC tower in various months Ambient

40.0

PDEC tower

Temperature (°C)

35.0 30.0 25.0 20.0 15.0 10.0 Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov Dec

Month

•PDEC system works very well in the summer months For example,in May, the temperature of cooled air leaving the tower is about 25°C while the corresponding ambient temperature is about 38 °C. Thus, the drop in day-time temperature is significantly high in May, i.e. about 13 °C.

Implications of PDEC system ADVANTAGES • Low cost single pass system • Easy to maintain • Entry of birds and pests prevented • Charcoal tray to filter out dust • Sophisticated water treatment is not required • Single tower serving multiple floors • Can be used for pre-cooling the building at night DISADVANTAGES • High humidity • Noise due to spraying of water

Energy Savings Estimated Savings • Approx. Rs. 3.5 lakhs/ annum

Simple Payback Period • 5 years

Conclusions – Part 2 Passive solar architecture can be used effectively in a non-conditioned building in a hot and dry climate to: – Provide indoor comfort – Reduce consumption of energy Acknowledgements: Kembhavi Architecture Foundation, Hubli and Karnataka State Police Housing Corporation, Bangalore

Thank You