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January 2010

Phase 2 Report on Environmental Building

Regulations & Guidelines to achieve Energy

Efficiency in Bangalore City

Prepared for

Renewable Energy & Energy Efficiency Partnership

Vienna International Center, Austria

w w w . t e r i i n . o r g

www.teriuniversity.ac.in

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The Energy and Resources Institute 2010

Suggested format for citation

T E R I. 2010

Development of Building Regulations and Guidelines for Energy

Efficiency, Bangalore City

The Energy and Resources Institute. 154 pp.

[Project Report No. 2009BS03]

For more information

T E R I University Tel. 25356590

Centre for Research on Sustainable [email protected] Science Group(CRSBS) Fax25356589Southern Regional Centre Webwww.teri in.orgBangalore 560 071 India +91 Bangalore (0) 80

India

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TERI University Project Team

Ms. Minni Mehrotra

Ms. Mili Majumdar

Mr. Pradeep Kumar

Ms. Priyanka Kochhar

Dr. Hina Zia

Mr. T Senthil Kumar

Mr. Nitish Poonia

Mr. Kiriti Sahoo

TERI University Project Advisor

Dr. A Ravindra, Advisor to Chief Minister of Karnataka (Urban Affairs)

Mr. P R Dasgupta, I A S (Retd), Senior Advisor & Coordinator for TERI South Regional Centre

Secretarial Assistance

Ms. Jyothi

Acknowledgements

We are thankful to the Government of Karnataka officials for their full co-operation and support to carry

this project in Bangalore city. We would like to thank:

1. Sri Bharat Lal Meena, I.A.S, Commissioner, Bruhat Bengaluru Mahanagara Palike, Narasimha Raja

Square, Bangalore 560 002

2. Sri Thirukangowdru, Joint Director Town, Bruhat Bengaluru Mahanagara Palike, Narasimha Raja

Square, Bangalore 560 002

3. Sri Siddaiah, I.A.S, Commissioner, Bangalore Development Authority, T. Chowdaiah Road, Kumara

Park West, Bangalore 560 0204. Sri R. Rangaswamy, Executive Engineer (Electrical) Bangalore Development Authority, T. Chowdaiah

Road, Kumara Park West, Bangalore 560 020

5. Sri T. D. Nanjundappa, Engineer Officer-III, Bangalore Development Authority, T. Chowdaiah Road,

Kumara Park West, Bangalore 560 020

6. Sri Tushar Girinath, MD, Bangalore Electricity Supply Company Limited, K R Circle Bangalore - 560

001

7. Sri B. N. Sathyaprema Kumar, General Manager (HRD), Bangalore Electricity Supply Company

Limited, K R Circle Bangalore - 560 001

8. Sri Shivananda Murthy H G, MD, Karnataka Renewable Energy Development Ltd., No.19, Maj. Gen.

A D Loghanathan, INA Cross, Queen's road., Bangalore - 560052.

9. Dr H. Naganagouda, Assistant General Manager, Karnataka Renewable Energy Development Ltd.,

No.19, Maj. Gen. A D Loghanathan, INA Cross, Queen's road., Bangalore - 560052.

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List of Contents

IN T RODUC T I ON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . 1

EXI S T I N G BY E LAW S & RE V I S I O N S PR O P O S E D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

FR A ME W O R K O F EN V I R O N ME N T A L B U I LD I N G RE G U LA T I O N S A N D GU I D E LI N E S

F O R BA N GA L OR E C I T Y. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

GUI DELI N E 1: SOLAR PASS I V E DESIGN FOR NEW BUI LDI N G S . . . . . . . . . . . . . . . . . . . .4

1.1 .1 MA NDA T OR Y CLA US E T O B E IN CL UD E D IN TH E RE V I S E D BY E LA W S . . 41.2 TE C H N I C A L N O T E S F O R SO LA R PA SS IV E DE SI GN F O R N EW B U I LD I N G S . . . . 4

1.2.1 S O LA R PA S S IV E DE S I G N . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

1.2.2 LA N DS CA PI N G . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

1.2.3 WA T ER B O D I E S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

1.2.4 O R I E N T A T I O N . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6

1.2.5 BU I LD I N G F O R M / S U R F A C E T O V O LU ME R A T I O . . . . . . . . . . . . . . . . . . . . . . . .8

1.2.6 O P T I MI Z A T I O N O F B U I LD I N G E N V E LO P E . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8

1.2.7 WALL S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

1.2.8 TH E R MA L S T O R A G E / T H E R MA L C A P A C I T Y . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

1.2.9 C O N D U C T A N C E . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .91.2.10 TH E R MA L I N S U LA T I O N . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

1.2.11 OP T I MI Z A T I O N O F R O O F . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

1.2.12 HE A T G A I N S T H R O U G H R O O F S C A N B E R E D U C E D B Y A D O P T I N G T H E

F O LLO W I N G T E C H N I Q U E S. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11

1.2.13 FE N E S T R A T I O N A N D SH A D I N G . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15

1.2.14 FI N I S H E S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15

1.2.15 .......BE N E F I T S O F ECBC R E C O MME N D E D E N V E LO P E I N C O MP A R I S O N

WI T H C ON V EN T IO N AL B UI LDIN G E NV E LO P E F O R A IR C ON DI TI ON E D

B U I LD I N G S I N BAN G AL O R E . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

1.2.16 EXT E R N A L S H A D I N G O F T H E E N V E LO P E . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .171.3 L IF E CY CL E C O ST AN A LY S I S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17

1.4 DA YL I GHT IN T E G R A T I O N . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

1.5 BU I LD I N G E N V E LO P E O P T I MI Z A T I O N F O R N A T U R A LLY V E N T I LA T E D

B U I LD I N G S T O A C H I E V E T H E R MA L C O MF O R T . . . . . .. . . . . .. . . . .. . . . . .. . . . .. . . . 18

1.6 LO W E N E R G Y PAS SI V E C O O LI N G S T R A T E G I E S F O R BAN GAL OR E . . . . . . . . . . . .21

1.6.1 VE N T I LA T I O N . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21

1.6.2 RA DI A TI V E CO OLI N G . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

1.6.3 SO ME LO W E N E R G Y C O O LI N G & D E S I G N S T R A T E G I E S T H A T C O U LD B E

A DO P T E D IN R ES I DE NT IA L B UIL DI N GS IN BA N GA L O R E A R E DESC RI BE D

B E LO W . T H E S E S T R A T E G I E S W E R E A N A LY S E D I N TRNSYS S O F T W A R E . . . . 25

1.7 EX A M P L E O F A NA T U R AL LYVE N T I LA T E D O F F I C E BU I LD I N G I N BAN GA L OR E

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

1.8 S U MMA R Y : . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

1.8.1 NA TUR AL LY V EN T I LA T E D BU IL DI N GS R E COM ME N DA T I ON S . . . . .. . . . . 26

1.9 GLO S S A R Y : . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . 26

1.10 RE F E R E N C E: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

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L I G H T I N G MA N UF A C T UR ER CO N TA CT DE T A IL S . . . . .. . . . . .. . . . .. . . . . .. . . . . .. . . . . . . 27

GUI DELI N ES 2: P ROVI DE ROOF T REAT M EN T T O C UT H EAT G AI N S . . . . . .. . . . .. . . . 28

2. 1 MAN D A T OR Y CL A U SE T O B E I NC LU DE D IN T HE RE V I S E D BY E LA W S . . .. . .. . 2 8

2. 2 T E C H N I C A L G U I D A N C E . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

2.2.1 BR I E F IN T R O D U C T I O N . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

2.2.2 H E A T G A I N S T H R O U G H R O O F S C A N B E R E D U C E D B Y A D O P T I N G T H E

F O LLO W I N G T E C H N I Q U E S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

2.2.3 WH Y I S T H I S R E Q U I R E D? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

2.2.4 HO W I S I T B E N E F I C I A L? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

2. 3 GLO S S A R Y : . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

2. 4 RE F E R E N C E S: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

GUI DELI N E 3: WI N DOWDESIGN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

3. 1 FO R A I R - C O N D I T I O N E D B U I LD I N G S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

3. 2 FO R NO N-C O N D I T I O N E D B U I LD I N G S. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

3.3.1 WI N D O W S I N AI R-CO N D I T I O N E D B U I LD I N G S . . . . .. . . . . .. . . . . .. . . . . .. 41

3.3.2 WI N D O W S I N N ON -C O N D I T I O N E D B U I LD I N G . . . . .. . . . . .. . . . . .. . . . . .. 46

3.3.3 WI N D O W D E S I G N F O R NA T UR A L V E N TI L A TI ON . . . . .. . . . . .. . . . .. . . . . . 50

3. 4 GLO S S A R Y . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . 54

3. 5 RE F E R E N C E S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

GUI DELI N E 4: EN ERG Y EFFI C I EN C Y I N ART I FI C I AL LIGHTING . . . . . .. . . . .. . . . . . 56

4.1.1 FOR B U I LD I N G S W I T H C O N N E C T E D E LE C T R I C A L LO A D MO R E T H A N

100 K W. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . 56

4.1.2 FO R RE S I D E N T I A L B U I LD I N G S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

4.2.1 C O MME R C I A L & RE S I D E N T I A L B U I LD I N G S . . . . . .. . . . .. . . . . .. . . . .. . . . . 57

4.3.1 EF F I C I E N C Y I N AR T I F I C I A L L I G H T I N G SC H E ME . . . . .. . . . . .. . . . .. . . . . . 58

4.3.2 EXT E R N A L L I G H T I N G . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

4.3.3 IN T E R N A L L I G H T I N G F O R N EW C O MME R C I A L B U I LD I N G S . . .. . .. . .. 61

4.3.4 RE T R O F I T T I N G O P T I O N S I N EXI S T I N G C O MME R C I A L B U I LD I N G S . . . .774.3.5 IN T E R N A L L I G H T I N G F O R N EW RE S I D E N T I A L B U I LD I N G S . . . . . . . . . . .77

4.3.6 RE T R O F I T T I N G O P T I O N S I N EXI S T I N G R E S I D E N T I A L B U I LD I N G S . . . 8 0

GUI DELI N E 5: EN ERG Y EFFI C I EN T AIR CON DI T I ON I N G SY ST EM DESI G N FOR

BUI LDI N G S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

5. 1 GU I D E LI N E: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

5.1.1 MAN DA T OR Y CL A U SE T O B E I N CL U DE D IN T H E RE V I S E D BY E LA W S 83

5. 2 TE C H N I C A L N O T E S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

5.2.1 AI R C O N D I T I O N I N G . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

5.2.2 GU I D E LI N E S O N O P T I MI Z A T I O N O F C O O LI N G LO A D E S T I MA T I O N . .. 8 4

5.2.3 GU I D E LI N E S O N AHU S P E C I F I C A T I O N S T O A C H I E V E E N E R G Y E F F I C I E N C Y . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87

5.2.4 GU I D E LI N E S F O R E N E R G Y E F F I C I E N T C H I LLE R S . . . . .. . . . . .. . . . .. . . . . 90

5.2.5 GU I D E LI N E S F O R E N E R G Y E F F I C I E N T C O O LI N G T O W E R . . . . . .. . . . . .. 93

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GUI DELI N E 6: REPLACE EXISTING EQUIPMENT BY MINIMUM 3 ST AR RAT ED

BEE LABELED AP P LI AN C ES EQUI P M EN T AN D USE M I N I M UM 3 ST AR

RATED BEE LABELED AP P LI AN C ES/ EQUI P M EN T I N ALL N EW

BUI LDI N G S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94

MA N DA T O R Y R EQ UI R EM EN T I N ALL P RO C UR EM EN T N O RM S FO R G O V ERNM E N T

A ND P UB LIC BU IL DIN G S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94

6.1.1 S T A R R A T I N G F O R F R O S T F R E E R E F R I G E R A T O R . . . . .. . . . . .. . . . .. . . . . . 96

6.1.2 ST A R RA TI N G - RO OM AIR C O N D I T I O N E R S . . . . . .. . . . .. . . . . .. . . . .. . . . . 97

6.1.3 ST AR RA T IN G - D I R E C T C O OL RE F R I G E R A T O R . . . . .. . . . . .. . . . . .. . . . . . 97

6.1.4 ST A R RA TI N G PL A N: C E I LI N G FA N S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98

6.1.5 STAR RAT IN G P L AN : ELE C T R I C GE Y S E R S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99

6.1.6 ST A R RA TI N G PL A N CO L O U R T E LE V I S I O N S. . . . . . . . . . . . . . . . . . . . . . . . . .100

6.1.7 WH Y I S T H I S R E Q U I R E D? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .103

6.1.8 H O W I S I T B E N E F I C I A L? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .103

GUI DELI N E 7: SOLARWA TE R HEATING SY ST EM S F OR DOM EST I C AN D

C OM M ERC I AL BUI LDI N G S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .105

7.1 MAN D AT OR Y R E QUIR EM EN T IN BY EL AW. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .105

7.2.1 G U I D E LI N E S F O R D E S I G N , I N S T A LLA T I O N , A N D U S E O F S O LA R W A T E R

H E A T I N G S Y S T E MS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .109

7.2.2 GU I D E LI N E S F O R S Y S T E M S E LE C T I O N A N D U S E . . . . . . . . . . . . . . . . . . . . . 110

7.2.3 GU I D E LI N E S F O R I N S U LA T E D H O T W A T E R P I P I N G . . . . . .. . . . . .. . . . . . 110

7.2.4 H O W I S I T B E N E F I C I A L? /WH Y I S T H I S R E Q U I R E D? . . . . . .. . . . .. . . . . . 111

GUI DELI N ES 8: EN ERG Y EFFI C I EN T ELEC T RI C AL SY S T EM S FOR BUI LDI N G S 116

8. 1 GU I D E LI N E F O R EN E R G Y EF F I C I E N T ELE C T R I C A L S Y S T E MS F O R B U I LD I N G

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116

8.1.1 MAN D A T OR Y CL A U SE T O BE INC LU DED I N T HE RE V I S E D BY E LAW S 116

8. 2 TE C H N I C A L N O T E S F O R ELE C T R I C A L S Y S T E MS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116

8.2.1 G U I D E LI N E S I N ELE C T R I C A L S Y S T E M D E S I G N . . . . .. . . . . .. . . . . .. . . . . . 1168.2.2 GU I D E LI N E S O N O P T I MI Z A T I O N O F E LE C T R I C A L L O A D . . . . . .. . . . .. . 117

8.2.3 GU I D E LI N E S O N T R A N S F O R ME R RA T IN G AN D SE LE C T I O N . . . . .. . . . 119

8.2.4 GU I D E LI N E S O N S E LE C T I O N O F ELE C T R I C A L MO T O R S . . . . . . . . . . . . .120

8.2.5 G U I D E LI N E S O N I MP R O V E ME N T O F P O W E R F A C T O R . . . . . . . . . . . . . . . . 122

8.2.6. GU I D E LI N E S O N C H E C K ME T E R I N G A N D MO N I T O R I N G . . . . . .. . . . . . 125

8.2.7 GU I D E LI N E S O N D I S T R I B U T I O N S Y S T E M LO S S E S . . . . . . . . . . . . . . . . . . . . 126

8.2.8 GUIDELINES ON P O W E R B A C K U P S Y S T E MS . . . . . . . . . . . . . . . . . . . . . . . . . 129

8.2.9 GUIDELINES ON P OWER Q U A LI T Y . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131

GUI DELI N E 9: PERFORM M AN DAT ORY EN ERG Y AUDI T FOR EX I ST I N G

C OM M ERC I AL BUI LDI N G S WI T H C ON N EC T ED LOAD OF C ASES OF 50 0 KW OR 600 KVA AN D AP P LY EN ERG Y C ON SERVAT I ON M EASURES T O

REDUC E EN ERG Y C ON SUM P T I ON I N EX I ST I N G

C OM M ERC I AL/I N ST I T UT I ON AL BUI LDI N G S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133

9. 1 GU I D E LI N E: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133

9.1.1 MAN D AT OR Y R E QUIR EM EN T . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133

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9. 2 GU I D A N C E NO T E S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133

9. 3 EN E R G Y D E MA N D A N D C O N S U MP T I O N . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134

9. 4 AU D I T O F I N D I V I D U A L S Y S T E MS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137

9.4.1 ELE C T R I C A L S Y S T E M . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137

9.4.2 L I G H T I N G SY ST EM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .139

9.4.3 HVAC S Y S T E M . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .144

9. 5 C O N T R O LS I N T H E HVAC S Y S T E M R E C O MME N D E D B Y EN E R G Y

CO N S E R V A T I O N B U I LD I N G C O DE (ECBC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152

9. 6 BE N E F I T S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . 153

9. 7 GLO S S A R Y . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . 153

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INTRODUCTION

In phase II of the project framing of environmental building regulations and guidelines to

achieve energy efficiency and integrate renewable energy in Bangalore city is completed.

It is proposed that the recommended regulations shall become a part of the existing

building bye laws of Bangalore city and a separate document on guidelines will be

published. This separate guidelines document will be available along with the building byelaws of Bangalore for the citizens of Bangalore city.

The study in the phase II was divided into two parts.

1. Study of existing building bye laws of Bangalore and identify sections which could

be improved or detailed out for achieving energy efficiency in Buildings in

Bangalore city.

2. A set of guidelines and regulations are proposed to achieve energy efficiency and

integrate renewable energy in the city.

Existing Bye Laws & Revisions Proposed

Under General Building Requirements following sections have been identified which need

revision or detailing.

Section 3.1.6 & 3.1.7, Width of road & Means of access

According to the regulation, F.A.R and height of the building shall be regulated according to

the width of public street or road. This is important to integrate daylight and natural

ventilation inside the buildings.

Revisions Proposed

This section has been detailed out. Relation between Height of building & separation

between two buildings has been established with respect to WWR (Window Wall Ratio) andLight transmittance of glass required for various Height / Separation ratio. This is included

in optimization of window design guideline.

Section 3.2 3 Basements

According to the existing bye law, when basement is used for car parking, the convenient

entry and exit shall be provided. Adequate drainage, ventilation, lighting arrangements and

protection against fire shall be made to the satisfaction of the authority.

Revisions proposed

The daylight and natural ventilation requirement for basements will be specified in detail in

the existing bye laws.

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2 Phase 2 Report on Environmental Building Regulations and Guidelines

framed fro Bangalore City

Section 3.3 Requirements of Building Services

3.3.1 Lighting and ventilation requirements

Natural ventilation and area of opening

According to the existing bye laws, rooms shall have, for admission of light and air, one or

more openings. Minimum aggregate area of openings excluding doors, shall not be less

than 1/6th

of the floor area in case of residential buildings. In case of other public buildingslike institutes, offices, hospitals etc minimum aggregate area of opening shall be not less

than 1/5th of the floor area.

Proposed guideline

There is a separate guideline framed on optimization of window design for air conditioned

and non air conditioned buildings.

Section 3.3.3 Transformer

According to the existing bye laws, where the specified load is 25kW or more a space for

locating the distribution transformers and associated equipment as per KERC code leaving

3.0m from the building and without obstructing the fire driveway within the premises has

to be provided.Revisions proposed

A separate guideline along with some mandatory clause has been framed for installation

and design of energy efficient electrical system in buildings. This includes a mandatory

requirement of Transformers to comply with Energy Conservation Building Code (ECBC) of

India requirements.

Section 3.3.5 Electrical installations, Air conditioning and heating

According to the existing bye laws, the planning, design and installation of air conditioning

and heating installations of the building shall be in accordance with Part VIII of the

National Building Code of India.

Revisions proposedA separate guideline along with some mandatory clause has been framed for design of

energy efficient air conditioning system for buildings in Bangalore.

Section 3.4.10 Solar energy

According to the existing bye laws,

Solar lighting and solar water heating is mandatory for all new

development/construction for different categories of buildings. If solar lighting and

solar water heating is adopted, then refundable security deposit on fulfilling the

conditions shall be returned with 2% interest.

Solar photovoltaic lighting systems shall be installed in multi unit residential

buildings (with more than five units) for lighting the set back areas and drive ways.

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Revisions proposed

In the existing bye law, the requirements for different building types are not clear;

this has been proposed in a separate guideline. Further incentives will be framed for

all mandatory regulations in phase 3 of this project.

For external solar lighting integration, separate guideline and mandatory clause has

been framed.

Frame work of Environmental Building Regulations and Guidelines forBangalore CityPart II of this report below comprises of the environmental building guidelines and

mandatory regulations framed for Bangalore city to achieve energy efficiency and integrate

renewable energy. Briefly 9 sections of guidelines & regulations have been framed, which

are described below and further detailed out later.

1. Solar passive design integration in new buildings.

2. Provide roof treatment to cut heat gains.

3. Window design for day lighting, ventilation and to reduce solar heat gains.

4. Artificial lightinga. Energy efficient external lightingb. Renewable energy based external lightingc. Efficient indoor lighting for new commercial buildings, follow ECBC

prescriptive / mandatory criteria for lighting design

d. Efficient indoor lighting for new residential buildingse. Retrofit options for existing commercial buildings

f. Retrofit options for existing residential buildings

5. Energy efficient air conditioning design for buildings.

6. Use of BEE labeled equipments and appliances to achieve energy efficiency innew and existing buildings.

7. Solar water heating systems for residential and commercial buildings.

8. Energy efficient electrical systems for building

9. Perform mandatory energy audit for existing commercial buildings with

connected load in cases of 500kW or 600KVA and reduce energy consumptionby 20% over previous year.

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GUIDELINE 1: Solar Passive Design for New Buildings

1.1 Guideline for Solar Passive design for New Buildings

Achieve thermal and visual comfort inside the building by

using natural energy sources and sinks, such that there is

significant reduction in energy consumption by

conventional air conditioning and artificial lighting in a

building.

1.1.1 Mandatory clause to be included in the Revised Bye Laws

Design external shading for windows to protect heat gains from direct solar radiation and

for protection against rain. In air conditioned buildings windows should comply with ECBC

requirement. Roof should either comply with ECBC requirements or should be shaded.

Table 1.1: Roof assembly U-factor requirements as per ECBC 2007

Climate zone 24-Hour use buildings

Hospitals, Hotels, Call centers etc.

Daytime use buildings

Other building Types

Maximum U-factor of the overall assembly (W/m2K) Maximum U-factor of the overall assembly

(W/m2K)

Moderate U-0.409 U-409

Vertical Fenestration U-factor and SHGC Requirements (U-factor in W/m2K)

ClimateMaximum U-factor (W/m2-

K)Maximum SHGC for

WWR 40%Maximum SHGC for

40%

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Figure 1.1: Water and trees as landscape

elements at Sangath, Ahmedabad

architecture design features and taking advantage of existing natural resources on the site.

Designers can achieve energy efficiency in the buildings they design by studying the macro

and micro climate of the site, applying solar passive and bio climatic design features and

take advantage of natural resources on site.

Designers can achieve solar passive building design by following the below mentioned

steps.

1. Modulating the microclimate of the site through landscaping

2. Optimization of orientation and building form

3. Optimization of building envelope and window design to reduce cooling demand

4. Daylight integration to reduce artificial lighting demand.

5. Low energy passive cooling strategies

1.2.2 LandscapingLandscaping by vegetation is one of the most effective ways

of altering micro climate for better conditions. Trees

provide buffer to sun, heat, noise, air pollution.

Landscaping can be used to direct or divert the air flow

advantageously. Trees help to shade the building from

intense direct solar radiation. Tree species could be

selected depending upon climate zone and building design.

Deciduous trees for example, provide shade in the summer

and sunlight in the winter when their leaves fall. Planting

them on West and South West orientation of a building

provides natural shade. Evergreen trees provide shade and

wind control round the year. Natural cooling without air conditioning can be achieved by

locating trees to channel cool breeze inside the buildings. Additionally, the shade created by

trees, reduces air temperature of the micro climate around the building through evapotranspiration. Properly designed roof gardens help to reduce heat loads in a building.

1.2.3 Water BodiesWater has a moderating effect on the air temperature of the micro climate. It possess very

high thermal storage capacity much higher than the building materials like Brick, concrete,

stone. A large body of water in the form of lake, river, fountain has the ability to moderate

the air temperatures in the micro climate. Water evaporation has a cooling effect in the

surroundings. It takes up heat from the air through evaporation and causes significant

cooling.

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Figure 1.2: Average daily solar radiation received on North orientation facade

1.2.4 OrientationIn solar passive buildings, orientation is a major design consideration, mainly with regard

to solar radiation, daylight and wind. The orientation of the building should be based on

whether cooling or heating is predominant requirement in the building. The amount of

solar radiation falling on a surface varies with orientation. In tropical climate zones for

example, North Orientation receives solar radiation with minimum intensity as seen infigure 2. Thus in tropical climate like India long facades of buildings oriented towards

North South are preferred. South orientation receives maximum solar radiation during

winters which is preferable. East and West receive maximum solar radiation during

summer. West is a crucial orientation because high intensity of solar radiation is received

during evening hours, when the internal gains are also at its peak. Thus, designers need to

be very careful while designing West faade and spaces behind west faade. Orientation also

plays an important role with respect to wind direction. At building level, orientation affects

the heat gain through building envelope and thus the cooling demand, orientation may

affect the daylight factor depending upon the surrounding built forms, and finally the

depending upon the windward and leeward orientation fenestration could be designed to

integrate natural ventilation

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Figure 1.3: Average daily solar radiation received on South orientation facade

Figure 1.4: Average daily solar radiation received on East orientation facade

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Figure 1.5: Average daily radiation received on West orientation facade

1.2.5 Building form / surface to volume ratio

Thermal performance of volume of a space inside the building has direct relationship withthe area of the envelope enclosing that volume. This parameter known as the S/V (Surface /

volume) ratio, is determined by the building form. Building form affects solar access and

wind exposure as well as the rate of heat gain and heat loss through the external envelope. A

compact building gains less heat during the daytime and losses less heat at night. In

Bangalore, buildings that are compact and have low S/V ratio to reduce heat gains are

preferred. Four building geometries were studied for Bangalore climate zone to analyse the

most efficient form which gains minimum heat gain from the external surfaces. These were

square, rectangular, courtyard and circular.

In Moderate climate zone of Bangalore, the Energy Performance Index (EPI) of circular

building is lowest, in comparison to other building forms. This is because circular buildinghas the lowest Surface to Volume ratio. It is observed in VisualDOE software results that

due to circular geometry, the conduction gains from the building envelope as well as solar

gains from windows are least, in circular geometry in comparison to other building

geometries.

The building form also determines the air flow around the building and hence the

ventilation rates inside. Circular form of building is an aerodynamic form which would also

help enhance natural ventilation inside the building. The depth of the building determines

the amount of daylight which can penetrate inside the building. Deeper the building, more

artificial lights required which is not preferred in an energy efficient building.

1.2.6 Optimization of building envelope

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Choice of building material for the envelope is important to reduce the energy consumption

of the building, through reduced solar heat gain or loss thus reducing air conditioning

loads. Optimized selection of building material for external envelope also plays an

important role in achieving thermal comfort in buildings where thermal comfort is achieved

through passive cooling strategies such as natural ventilation.

Building envelopeBuilding envelope components are the key determinants of the amount of heat gain or loss

and wind that enters inside the building. The important components of building envelope

which affect the performance of the building are:

Walls

Roof

Windows

Surface finishes

1.2.7 Walls

Walls are a major part of the building envelope, which are exposed to external environmentconditions (solar radiation, outside air temperature, wind, precipitation). The composition

of wall and thereby its heat storing capacity and heat conduction property has a major

impact on indoor thermal comfort in naturally ventilated buildings and on cooling loads in

air conditioned buildings. The wall material, thickness, finishes should be selected

according to climate zone and buildings comfort requirement.

1.2.8 Thermal storage / thermal capacityThermal capacity is the measure of the amount of energy required to raise the temperature

of a layer of material, it is a product of density multiplied by specific heat and volume of the

construction layer. The main effect of heat storage within the building structure is to

moderate fluctuation in the indoor temperature.

In a building system, we can understand thermal mass as the ability of a building material

to store heat energy to balance the fluctuations in the heat energy requirements or room

temperature in the building due to varying outside air temperature. The capacity to store

heat depends upon the mass and therefore on the density of the material as well as on its

specific heat capacity. Thus, high density materials such as concrete, bricks, stone are said

to have high thermal mass owing to their high capacity to store heat while lightweight

materials such as wood, or plastics have low thermal mass. The heat storing capacity of

building materials help achieve thermal comfort conditions by providing a time delay. This

thermal storage effect increases with increasing compactness, density and specific heat

capacity of materials.

1.2.9 ConductanceConductivity (K) is defined as the rate of heat flow through a unit area of unit thickness of

the material, by a unit temperature difference between the two sides. The unit is W/mK

(Watt per metre - degree Kelvin). The conductivity value varies from 0.03 W/mK for

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insulators to 400W/mK for metals. Materials with lower conductivity are preferred, as they

are better insulators and would reduce the external heat gains from the envelope.

1.2.10 Thermal insulationThermal insulation plays an important role in reducing the conductance or U value

(W/m2K) of walls and roof. Insulation should always be placed on the hotter side of the

surface.Thermal mass is not a substitute of insulation; in fact a high thermal mass material is

usually not a good thermal insulator. Buildings should use insulation in combination with

heat storing material. This storing mass should be placed towards the inside in passively

cooled buildings.

Energy Conservation Building Code (ECBC) requirement for external walls

For air conditioned buildings, ECBC recommends thermal performance for external opaque

walls. These are mentioned below:


Hospitals, Hotels, Call centres etc.



Maximum U-factor of the overall assembly (W/m2K) Maximum U-factor of the overall assembly (W/m2K)


1.2.11 Optimization of roofFig 1.6, shows the intensity of solar irradiation is maximum on the horizontal plane which is

the roof. Conductance of heat from the roof can be very high if not insulated well. This can

result in increased cooling load if the space below is air conditioned or high discomfort

hours if the space below is naturally ventilated.

Figure 1.6: Average daily Intensity of solar radiation incident on horizontal roof surface in Bangalore

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1.2.12 Heat gains through roofs can be reduced by adopting the followingtechniques.

Green roof concept

Green roofs have the potential to improve the thermal

performance of a roofing system through shading, insulation,

evapo transpiration and thermal mass, thus reducing a buildings

energy demands for space conditioning. The green roof

moderates the heat flow through the roofing system and helps in

reducing the temperature fluctuations due to changing outside

environment. Figure 1.7: Roof of buildings with roof garden

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Green roof is a roof of a building that is partially or

completely covered with vegetation and soil that is planted

over waterproofing membrane. If widely used green roofs can

also reduce the problem of urban heat island which would

further reduce the energy consumption in urban areas.

Use of high reflective material on roof top

Use light coloured roofs having an SRI (solar reflectance

index) of 50% or more. The dark coloured, traditional

roofing finishes have SRI varying from 5 - 20%. A good

example of high SRI is the use of broken china mosaic and light coloured tiles as roof finish,

which reflects heat off the surface because of high solar reflectivity and infrared emittance,

which prevents heat gain and thus help in reducing the cooling load from the building

envelope.

Thermal insulation for roof

Well insulated roof with the insulation placed on the external side is an effective measure toreduce solar heat gains from the roof top. The insulated materials should be well protected

by water proofing.

For air conditioned spaces, Energy Conservation Building Code (ECBC) recommends the

thermal performance for external roof for all the five climate zones in India. Bangalore falls

under Moderate climate zone, the maximum U-value recommended by ECBC for moderate

climate zone is mentioned below:



Hospitals, Hotels, Call centers etc.


Other building TypesMaximum U-factor of the overall assembly (W/m2K) Maximum U-factor of the overall assembly (W/m2K)


Examples of ECBC compliant roof assembly

Roof Ufactor (SI) Ufactor Btu/h (sf-oF) Rs/sf

Foam concrete or perlite instead of mud Phuska 0.069 0.012 130

RCC slab with Extruded polystyrene 2.4 36 kg/m3 0.380 0.067 252

RCC slab with Extruded polystyrene 3 36 kg/m3 0.312 0.055 278

RCC slab with Expanded polystyrene (thermocole) 3 24 kg/m3 0.409 0.072 205

RCC slab with Phenolic foam 2.4 32 kg/m3 0.363 0.064 270

RCC slab with Phenolic foam 3 32 kg/m3 0.301 0.053 302

RCC slab withPolyurethane spray 2.4 42 2 kg/m3 0.319 0.056 229

RCC slab withPolyurethane spray 3 42 2 kg/m3 0.259 0.046 246

RCC slab withPolyisocyanurate spray 2.4 42 kg/m3 0.329 0.058 233

RCC slab withPolyisocyanurate spray 3 42 kg/m3 0.267 0.047 251

Figure 1.8: Broken china mosaic can be used as an

external roof finish to reflect the incident solar radiation

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Insulation + cool roof

Along with lower U-value for roof, ECBC also recommends cool roof. Cool roofs are roofs

covered with a reflective coating that has high emissivity property which is very effective in

reflecting the suns energy away from the roof surface. These cool roofs are known to stay

10deg to 16dg C cooler than normal roof under a hot summer day. This quality greatly helps

in reducing the cooling load that needs to be met by the HVAC system. Combination of

insulated roof along with cool roof has higher saving energy potential.

External shading of roof

Shading of roof through design features

like pergola or solar photovoltaic panels

help reduce the incident direct solar

radiation on the roof surface. This in

turn helps to reduce the sol air

temperature of the roof and conduction

gains in the space below. It is observed

using software simulations that shadingof roof has equal potential in reducing

the energy consumption by air

conditioning as that of an insulated roof.

Thermal properties of few building and insulating materials for reference are given below in

table 1.3.

Table 1.3: Thermal Properties of Building and Insulating Materials at Mean Temperature of 50deg.C

SL.

NO.

TYPE OF MATERIAL DENSITY THERMAL

CONDUCTIVITY*

SPECIFIC HEAT

CAPACITY

(1) (2) (3) (4) (5)

Kg / m3 W / (m.K) KJ / (kg.K)

Building Materials

1. Burnt brick 1 820 0.811 0.88

2. Mud brick 1 731 0.750 0.88

3. Dense concrete 2 410 1.74 0.88

4. R.C.C. 2 288 1.58 0.88

5. Limestone 2 420 1.80 0.84

6. State 2 750 1.72 0.84

7. Reinforced brick 1 920 1.10 0.84

8. Brick tile 1 892 0.798 0.88

9. Line concrete 1 646 0.730 0.88

10. Mud Phuska 1 622 0.519 0.88

11. Cement mortar 1 648 0.719 0.92

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12. Cement concrete 1 762 0.721 0.84

13. Cinder concrete 1 406 0.686 0.84

14. Foam slag concrete 1 320 0.285 0.88

15. Gypsum plaster 1 120 0.512 0.96

16. Cellular concrete 740 0.188 1.05

17. AC sheet 1 520 0.245 0.84

18. GI sheet 7 520 61.06 0.50

19. Timber 480 0.072 1.68

20. Timber 720 0.144 1.68

21. Plywood 640 0.174 1.76

22. Glass 2 350 0.814 0.88

23. Alluvial clay (40 percent sans) 1 958 1.211 0.84

24. Sand 2 240 1.74 0.84

25. Black cotton clay (Madras) 1 899 0.735 0.8826. Black cotton clay (Indore) 1 683 0.606 0.88

27. Tar felt (2.3 kg/m3) - 0.479 0.88

(Source, Handbook on Functional Requirements of buildings, SP:411987, BIS)

SL.

NO.

TYPE OF MATERIAL DENSITY THERMAL

CONDUCTIVITY*

SPECIFIC HEAT CAPACITY

(1) (2) (3) (4) (5)

Kg / m3 W / (m.K) KJ / (kg.K)

Insulating Materials

1. Expanded polystyrene 16.0 0.038 1.34



4. Foam glass 127.0 0.056 0.75

5. Foam glass 160.0 0.055 0.75

6. Foam concrete 320.0 0.070 0.92

7. Foam concrete 400.0 0.084 0.92

8. Foam concrete 704.0 0.149 0.92

9. Cork slab 164.0 0.043 0.96

10. Cork slab 192.0 0.044 0.96

11. Cork slab 304.0 0.055 0.96

12. Rock wool (unbonded) 92.0 0.047 0.84


14. Mineral wool (unbonded) 73.5 0.030 0.92

15. Glass wool (unbonded) 69.0 0.043 0.92


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17. Resin bonded mineral wool 48.0 0.042 1.00



20. Resin bonded glass wool 16.0 0.040 1.00


22. Exfoliated vermiculite (loose) 264.0 0.069 1.00

23. Asbestos mill board 1 397.0 0.249 0.88

24. Hard board 979.0 0.279 0.84

25. Straw board 310.0 0.057 1.42

26. Soft board 320.0 0.066 1.30

27. Soft board 249.0 0.047 1.30

28. Wall board 262.0 0.047 1.30

29. Chip board 432.0 0.067 1.26

30. Chip board (perforated) 352.0 0.066 1.26

31. Particle board 750.0 0.098 1.30

32. Coconut pith insulation board 520.0 0.060 1.09

33. Jute fibre 329.0 0.067 1.09

34. Wood wool board

(bonded with cement)

398.0 0.081 1.13

35. Wood wool board


674.0 0.108 1.13

36. Coil board 97.0 0.038 1.00

37. Saw dust 188.0 0.051 1.00

38. Rice husk 120.0 0.051 1.00

39. Jute felt 291.0 0.042 0.88

40. Asbestos fibre (loose) 640.0 0.060 0.84

1.2.13 Fenestration and ShadingOf all the elements of building envelope, windows and glazed areas are most vulnerable to

heat gains. Windows are required to bring inside natural daylight and wind, however, with

light it also brings in heat. Proper location, sizing and detailing of windows and shading

form is therefore a very important aspect in a solar passive building design. Hence window

design has been detailed out as separate guidelines, which should be referred separately.

1.2.14 FinishesThe external finish of a surface determines the amount of heat absorbed or rejected by it.

For example, a smooth and light coloured surface reflects more light and heat in

comparison to a dark surface. Light colours have higher emissivity and hence should be

preferred in Moderate climate zones like Bangalore where the intensity of solar radiation is

very high.

Emissivity is the measure of the capacity of a surface to emit radiation.

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LCC of conventional and ecbc envelope for air conditioned commercial buildings

0

10000000

20000000

30000000

40000000

50000000

60000000

70000000

80000000

90000000

0 1 2 3 4 5 6 7 8 9 10 1 1 1 2 1 3 1 4 1 5

Year

Rs Conventional envelope

ECBC envelope

The internal surfaces should also be finished in light colours, as that helps in obtaining

higher reflectance of light inside the space

1.2.15 Benefits of ECBC recommended envelope in comparison with conventionalbuilding envelope for air conditioned buildings in Bangalore

It is observed in air conditioned buildings, adopting ECBC envelope in building has highenergy saving potential. Energy simulation engine was used to quantify energy saving

potential in a daytime office building. It is observed that use of ECBC envelope results in

annual electricity saving up to 12% in comparison with conventional envelope. In this

analysis following was the ECBC and conventional envelope.

Walls Composition (External to internal) U value (W/m2K)

ECBC case Stone cladding+75mm Expanded Polystyrene+230mm Brick wall + internal

plaster

0.39

Conventional case External plaster +230mm brick wall + internal plaster 1.87

Roof Composition (External to internal) U value (W/m2K)

ECBC case Roof finish+75mm Expanded Polystyrene+150mm Concrete slab + internal

plaster

0.39

Conventional case Roof finish +150mm concrete slab + internal plaster 1.81

Glass

ECBC case (Double glazed unit) U value: 1.31 W/m2K

SHGC = 0.27

VLT = 40%

Conventional case (Single glazed unit) U-value =6.16

W/m2K

SHGC = 0.81VLT = 0.88

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1.2.16 External shading of the envelopeIt is observed that latitude , longitude of Bangalore recieves high intensity of solar

radiation. Though the air temperature is cool, making Bangalore fall under Moderate

climate zone, the solar radition intensity is very high. Thus one of the effective solar passive

design measure for Bangalore city is external shading of walls, roof, windows to reduce the

external heat gains. Simulation engine was used to quantify the saving potential in an air

conditioned building in Bangalore due to external shading. It is noted that energy saving

upto 15% is possible through shading of roof by using elements like pergola, shading of East

and west wall and through shading of windows.

1.3 Life Cycle Cost AnalysisThere can be three cases considered for optimized building envelope to provide maximum

energy saving potential due to optimum selection of building envelope.

These are:

1. Compliance of building envelope with ECBC (Energy Conservation Building Code)

recommendations.

2. Shading of envelope to reduce to reduce solar heat gains. This includes shading of East

and West orientation facades, shading of roof and shading of windows.

3. Shading of East & West walls, shading of roof and ECBC compliant window.

Case % Energy saving

potential

% Increment in initial

cost

% Saving in Life

Cycle Cost (LCC)

Pay back period

Base case - - -

ECBC envelope 13%% 1.3% 1% 8 years

Shaded envelope 16% 1.2% 1.9% 5 years

Shaded walls, roof andECBC window

16% 1.3% 1.9% 5 years

Thus it is recommended from the above analysis that :

Windows in air conditioned spaces should comply with ECBC recommendation.

Windows in naturaly ventilated spaces should be fully shaded.

Roof should be either compliant with ECBC recommendations or should be shaded.

East and West walls should be shaded.

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Life Cycle Cost Analysis for building envelope options

0

10

20

30

40

50

60

70

80

90

100

110

120

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Years

Rupees(Million)

Bas e cas e ECBC env elope c as e Propos ed Shading env elope c as e Propos ed s hadingw all,roof+ec bc glas s

1.4 Daylight IntegrationDaylight is a natural source of light, which meets all the requirements of good lighting.

Daylight provides a dynamic environment inside the building in consonance with the

nature outdoors. Windows in buildings establish contact with nature through direct view

and admit daylight inside. Adequate provision of daylight in buildings through proper

planning of windows, in respect of position, area and shape is therefore an important aspect

of a good building design. Daylight integration helps reduce dependence on artificial

lighting and thus reduction in electricity consumption of the building. Details on daylight

integartion is part of the window guideline.

1.5 Building envelope optimization for naturally ventilated buildings toachieve thermal comfort

Optimizing envelop requirement is one of the most important strategies to lower down heat

built up in the interior space , hence plays a vital role in achieving thermal comfort as

prescribed in the National Building Code 2005 for Naturally ventilated buildings.

Optimize building envelope to reduce heat gains and maximize thermal comfort in naturally

ventilated building.

Buildings occupied for 24 hoursResidences

For the achievement of thermal comfort in the naturally ventilated spaces of residences,

following guidelines should be followed:

1. For the effectiveness of natural ventilation, window should be designed as per the

guideline outlines in window design for Natural ventilation.

2. Windows should be fully shaded in order to maximize thermal comfort in the space.

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3. Building envelope should be as per the recommendations included in this guideline.

This recommended envelope design is for naturally ventilated residential spaces with 6

air change per hour.

Buildings occupied for Day time hours (9 hours)

Offices

For the achievement of thermal comfort in the naturally ventilated office spaces, following

guidelines should be followed:

For the effectiveness of natural ventilation, window should be designed as per the guideline

outlined in Window Design for Natural Ventilation. Windows should be fully shaded in

order to maximize thermal comfort in the space. Building envelope should be as per the

recommendations included in this guideline. Building envelope should be as per the

recommendations included in this guideline. This recommended envelope design is for

naturally ventilated office spaces with 6 air change per hour. Optimum Building Envelop

Configuration for Naturally Ventilated Residences and Offices:

The recommended envelop of the space shall be as per the following properties:

Table 1.4: Envelop Specifications

Envelope with brick wall Composition U-value

Wall Plaster + brick + plaster 2.203

Roof (Insulated) Plaster + concrete + expanded polystyrene + plaster + stone 0.349

Floor Floor + stone + concrete 0.417

Glass for opening Single glazing unit fully shaded -

Envelope with concrete wall Composition U-value

Wall Plaster + concrete + plaster 3.443

Roof (Insulated) Plaster + concrete + expanded polystyrene + plaster + stone 0.349


Glass for opening Single glazing unit fully shaded -

Envelope with mud-block

wallComposition U-value

Wall Plaster + mud block + plaster 3.443

Roof (insulated) Plaster + concrete + expanded polystyrene + plaster + stone 0.349


Glass for opening Single glazing unit (fully shaded) -

1. The U-Value prescribed in the table should be taken as recommendation while

designing the roof, wall, and floor component.

2. For the clarity of the user it should be noted that, the different combinations of envelopdiffers from each other with respect to only wall material; while the roof , floor and

glazing type remains the same.

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Figure 1.9: Zone Temperature conditions of non air conditioned space in office and residences on hottest day (April

11) of the year

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1.6 Low energy Passive Cooling Strategies for Bangalore

Bangalore falls under moderate climate zone with favorable outdoor conditions to design

hybrid low energy buildings. Weather analysis for Bangalore shows that design strategies

such as shading from direct solar radiation and natural ventilation are very effective in

achieving comfort in non air conditioned living spaces. High thermal mass and evaporative

cooling are other effective design strategies shown in figure below reference: Climate

calculator)

1.6.1 VentilationVentilation fulfills a number of requirements associated with human comfort:

Health: respiration, odour avoidance and pollutant removal.

Cooling: removal of heat produced by internal and solar gains, both during daytime and

at night time.

Comfort: Provision of air movement to increase perceived cooling.

Methods of ventilation

Ventilation requirement could be met by the following ways:

1. Natural ventilation

2. Mechanical ventilation

3. Mixed mode ventilation

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Figure 1.10: Cross ventilation achieved through

openings

Figure 11: Stack effect through openings at

different level.

Natural Ventilation

Natural ventilation systems rely on pressure to move fresh air through buildings.

Pressure difference can be caused by wind (cross ventilation) or the buoyancy effect

created by temperature differences or differences in humidity (stack effect). In both the

cases the amount of ventilation critically depends on design of openings, their size and

placement. Natural ventilation unlike forced ventilation uses natural sources like wind

and buoyancy to deliver fresh air into the building.

Cross Ventilation

A pressure is generated on a surface whenever moving

air is obstructed or deflected. The distribution of

pressure depends upon the wind direction and the

geometry of the surfaces. Pressures will generally be

positive on the windward sides of buildings and negative

on leeward sides. The lateral pressure distribution gives

rise to cross-ventilation; that is airflow from the windward

to the leeward side of the building. This requires that the

interior of the building is not sealed by dividing walls, or

that where rooms are double banked, openings at high level are provided.

Cross ventilation was assisted by having high level openings in the internal walls and

over doors in traditional houses.

Stack Effect

Air moves through a structure in response to pressure

differences generated by either the thermal buoyancy

(stack effect) or wind. Buoyancy pressures are generated

by air warmer than its surroundings as the warmer air is of

lower density than the cooler air.

The pressure generated is dependent upon the average

temperature difference between inside and outside and the height

of the 'stack' or column of warmer air. Where there are openings

at the top and bottom of the stack, the cooler heavier air will enter

the lower openings and displace the warmer lighter air at the top.

This is known as 'displacement ventilation', and if there is a

source of heat which maintains the stack, the flow will continue.

It is important to note that in these conditions air temperatures

low down will be close to outdoor temperatures and those

higher up will be warmer.

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Direct evaporative cooling, source Passivecooling techniques, B.Mohanty

Traditionally, this concept was used very commonly by having high ceilings in

conjunction with ventilators and low level openings, courtyards and atria.

Probable indoor wind speed

The available wind speed in a room with single window on the windward side is about

10 percent of outdoor velocity. The value however is increased upto 15 percent when

two windows are provided instead of one and wind impinges obliquely on them.

Effect of area of openings on the indoor wind velocity is depicted in the graph below.

Building design guidelines for natural ventilation

1. Maximize wind induced ventilation by orienting the longer facades of the building

towards predominant wind direction. However, if this is not possible, it could be oriented at

any convenient angle between 0o and 30o without loosing any beneficial aspect of the

breeze.

2. Inlet openings in the buildings should be well distributed and should be located on the

windward side at a low level, and outlet openings should be located on the leeward side at a

higher level, to maximize the stack effect.

3. Buildings should be sited where obstructions for summer

winds are minimum.

4. Naturally ventilated buildings should have a narrow floor

width, infact its difficult to naturally ventilate buildings with

floor depth more than 45feet.

5. For total area of openings (inlet and outlet) of 20 to 30% of

floor area, the average indoor wind velocity that could be

achieved is around 30% of outdoor wind velocity. Even onincreasing the size of window further, the maximum indoor

wind velocity does not exceed 40% of outside wind velocity.

6. Window openings should be operable by occupants.

7. In addition to the primary consideration of airflow in and out of the building, airflow

between the rooms of the building is important. Where possible, interior doors should be

designed to be open to encourage whole-building ventilation.

8. Use of clerestories or vented skylights, A clerestory or a vented skylight will provide an

opening for stale air to escape in a buoyancy ventilation strategy. The light well of theskylight could also act as a solar chimney to augment the flow. Openings lower in the

structure, such as basement windows, must be provided to complete the ventilation system.

Evaporative Cooling

Evaporative cooling lowers indoor air temperature by evaporative cooling. This cooling

strategy is also effective in Moderate climate of Bangalore. In evaporative cooling the

Nocturnal cooling

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sensible heat of air is used to evaporate the water, thereby releasing energy and air gets

cooled, which in turn cools the indoor living spaces.

Increase in contact between air and water increases the rate of evaporation. Water bodies

like ponds, lake or fountains in the landscape help reduce micro climate air temperature

around the buildings.

Traditionally also evaporative cooling has been used to cool the hot breeze. Water was usedcommonly to reduce local temperatures by evaporative cooling, to humidify the air and also

to clean the air by capturing dust particles. It has been calculated that the temperature of 1

cubic metre of air will be reduced by 1 C by the evaporation of 0-5 g of water (Evans). In

public buildings water in pools and fountains can be used as a cooling element combined

with a cross-ventilating arrangement of openings.

Figure 13: Ways of integrating evaporative cooling

Figure 12: HUL solar passive building in Bangalore with ponds

integrated in the circulation areas to integrate evaporative cooling.

1.6.2 Radiative cooling

Principle: If two elements at different temperatures are kept facing one another, a netradiation heat loss from the hotter element will occur until a state of equilibrium

between the two elements is achieved.

In order to have an appreciable net heat flux between the two bodies, the temperature

difference should be significant

Low energy passive design stretegies in residential building typology in Bangalore city

Thermal comfort through out the year can be easily achieved in residential buildings in

Bangalore by adopting the following passive design strategies:

Long faade oriented towards North South

East and West facades to be shaded

Solar chimneys integration to enhance natural ventilation

Insulated roof

Roof pond in certain areas for radiant cooling

Direct evaporative cooling

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1.6.3 Some low energy cooling & design strategies that could be adopted inresidential buildings in Bangalore are described below. These strategies wereanalysed in TRNSYS software.

1. Long faade oriented towards North South, this is based on the solar radiation

analysis for Bangalore city. East and West faade receive higher intensity of solarradiation throughout the year and hence short facades of the building should be

oriented towards East and West. This ensures minimum solar heat gain inside the

building.

2. Insulated roof: Solar analysis of Bangalore predicts high intensity of solar radiation

being received on horizontal surfaces. To reduce conduction gains from the roof, it

is very esstial to insulate the roof from outside.

3. Solar chimneys to enhance natural ventilation, through stack effect. Inlet openings

provided at lower level and outlet opening through solar chimney increase the

temperature difference between the hot air and cool air, this enhances the air

movement and therefore natural ventilation. Natural ventilation is very effective in

Moderate climate of Bangalore as the outside air temperature falls under comfortzone.

4. Radiant cooling is also effectice in Bangalore and therefore roof pond could be

provided wherever possible.

5. Evaporative cooling: In summer months in Bangalore which are April, May and

June evaporative cooling is effective, as the outside temperature is high and

Relative Humidity (RH) is lower. This can be integrated in buildings through

evaporative coolers, or wet Khas Khas integrated around windows and through

designing water bodies in the landscape.

1.7 Example of a Naturally Ventilated office Building in Bangalore

TERIs South Regional office is located in Bangalore which

forms an example of passive building in the Moderate climate

zone of India.

Following are some of key features of the building:

The building is oriented with long facades oriented North

South.

The building has maximum

openings in the North faade which

helps bring inside the building glarefree daylight and cool breeze.

The skylights are oriented towards

North, which provides uniform glare

free daylight through out the

building.

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Walls on the South faade are externally finished with

black kadappa stone with a cavity wall. This behaves

as a solar chimney. There are no openings at lower

level in this wall, only ventilators at the top of the wall

are provided for hot air to rise and escape. This

creates a negative pressure and starts pulling freshcool air from North side of the building. The building

works in natural ventilation mode through out the

year, and this is achieved as there are no floor to

ceiling partitions in the whole building.

There are roof gardens designed, which provide good insulation and moderates

fluctuation in temperature.

The month bill for energy consumption is about Rs 30,000 for the entire complex, with

daily average demand of 12 kW (peak at 18 kW). With floor area being 26,663 square

feet, the specific energy bill works out to be Rs 1.12 per square foot, which is almost one-

tenth of a conventional building with air conditioning.

1.8 Summary:Recommendations for air conditioned buildings

Long faade preferably towards North-South

East West faade to be shaded

Windows to comply with ECBC requirement.

Roof to either comply with ECBC or to be fully shaded.

Circular building form is preferable.

Light colour external finish.

1.8.1 Naturally ventilated buildings recommendations Long faade preferably towards North-South

East West faade to be shaded

Windows to be fully shaded.

Roof to be insulated or to be shaded.

Light colour external finish.

1.9 Glossary:Orientation: It is the direction an envelope element faces, i.e., the direction of a vector

perpendicular to and pointing away from the surface outside of the element.

Reflectance: The fraction of radiant energy that is reflected from a surface.

Solar heat gain coefficient: Solar heat gain coefficient (SHGC) is the fraction of

external solar radiation that is admitted through a window or skylight, both directly

transmitted, and absorbed and subsequently released inward.

Transmittance: The fraction of radiant energy that passes through a surface.

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U-factor: It measures the rate of heat transfer through a building element over a given

area, under standardised conditions. The usual standard is at a temperature gradient of 24

C, at 50% humidity with no wind.

1.10 Reference: Bureau of Indian Standards, 2005, National Building Code of India

A Knowledge Bank for Sustainable Building Design CD, MNRE & TERI, New

Delhi

Energy Conservation Building Code 2007, Bureau of Energy Efficiency, Ministry of

Power, Government of India

VisualDOE version 4.1 Software

Ecotect Version 5.0.

Lighting Manufacturer contact details

SN Name Address Contact details

Paint

1 THERMATEK (Ishaan

Industries)

ALA INC, No. 303,6th Main, Yellama

Temple Road, Indira Nagar, Bangalore-

560038.

Ph: 080 25352493Mobile: 9980560857

2 Kansai Nerolac Paints

Limited

Nerolac House, SY No 39/1, P C S

Industrial Estate, Banner gata Road

AREKER Village, Bangalore -560076

Ph: 080-26597145

Insulation

3 U. P. Twiga Fiberglass

Limited

No. 28/3 1st Floor, 23rd Cross,

Banashankari 2nd Stage Main Road,

Near State Bank of India, Bangalore -

560070

Ph: 080-26712510Mobile-9686406229

4 Lloyd Insulations (India)

Ltd

101-102, Oxford Chamber, No. 16,

Rustam Bagh Main Road, Bangalore:

560017

Ph: 080-25202084

Glass Products

5 3M Construction MarketCenter

Concorde block, UB City, 24, Vittal MalyaRoad, Bangalore-560001

Ph: 080-66595759Fax: 080-22231450

6 Saint-Gobain GlassIndia Ltd.

Sai Comples, 4th Floor, 114, M G Road,Bangalore 560 001

Ph: 080-25091123Fax: 080-25583795

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GUIDELINES 2:Provide roof treatment to cut heat gains

Provide roof treatment to cut down heat gain in the air-conditioned and naturally ventilated

space to maximize thermal comfort.

2.1 Mandatory clause to be included in the Revised Bye LawsAll exposed roof in air conditioned spaces and naturally ventilated shall comply with the ECBC

2007 requirement as outlined below or shall be shaded


Climate

zone

24-Hour use buildings




Maximum U-factor of the overall assembly (W/m2K) Maximum U-factor of the overall assembly(W/m2K)


The roof insulation shall not be located on a suspended ceiling with removable

Ceiling panels. (Mandatory)

2.2 Technical Guidance

2.2.1 Brief IntroductionOptimizing roof material can play vital role in lowering down heat built up in both air-

conditioned space and naturally ventilated space. Roof treatment is one of the effective

strategies to cut down heat gain helps in reducing cooling load from air conditioned space.

In the same way, it helps in maximizing thermal comfort in naturally ventilated space.

Roof optimization in Air Conditioned Space:

It is observed in air conditioned buildings, adopting ECBC envelope in building has highenergy saving potential. Energy simulation engine was used to quantify energy saving

potential in a daytime office building. . It is observed that in single storey buildings and in

double storey buildings, insulated + cool roof as recommended by ECBC has energy saving

potential up to 60% in comparison to conventional buildings. This saving potential

however, reduces with increase in number of floors and in case of high rise buildings, where

roof contribution towards external heat gains is minimized

Shading of roof also has similar energy saving potential. This could be achieved by

designing pergolas, trellis on roof or by installation of solar panels. Energy saving potential

in a building with two floors and built up area 3200m2, after complying to ECBC

recommendations and shading the roof are given below in the graph.


ECBC compliant

insulated + cool roo

Roof finish+75mm Expanded Polystyrene+150mm Concrete slab + internal plaster 0.39


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Recommended roof treatment for Naturally Ventilated spacesThermal comfort in a naturally ventilated space can be maximized by using appropriate

treatment for the roof. Computer simulation analysis was performed in order to investigate

the role of roof treatment to maximize thermal comfort in a naturally ventilated space.

Following are envelope configuration used for simulation analysis

Walls Composition (External to internal) U value (W/m2K)

ECBC case Stone cladding+75mm Expanded Polystyrene+230mm Brick wall + internal

plaster

0.39

Conventional case External plaster +230mm brick wall + internal plaster 1.87

The thermal comfort hours are further maximized when the surface reflectivity increased to

0.7 y using white paint on external roof surface and insulation thickness.


ECBC case Roof finish+75mm Expanded Polystyrene+150mm Concrete slab + internal plaster 0.39


Glass Type Properties

ECBC case (Single glazed

unit)U-value =6.16 W/m2K , SHGC = 0.81 , VLT = 0.88

Conventional case (Single

glazed unit)U-value =6.16 W/m2K , SHGC = 0.81 , VLT = 0.88

Energy use in conventional building, building

with ECBC compliant roof, building with shaded

roof

0

200,000

400,000

600,000

800,0001,000,000

1,200,000

base 0.30wwr ECBC + cool roof

0.30wwr

Shaded roof

0.30wwr

Energyuse(kWh)

Energy consumption kWh (Cooling+Lighting)

61% saving 62% saving

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2.2.2 Heat gains through roofs can be reduced by adopting the followingtechniques

Green roof concept

Green roofs have the potential to improve the thermal

performance of a roofing system through shading, insulation,

evapo-transpiration and thermal mass, thus reducing a

buildings energy demands for space conditioning. The green

roof moderates the heat flow through the roofing system and

helps in reducing the temperature fluctuations due to changing

outside environment.Figure 2.1: Roof of buildings with roof garden.

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Green roof is a roof of a building that is partially or completely covered with vegetation and

soil that is planted over waterproofing membrane. If widely

used green roofs can also reduce the problem of urban heat

island which would further reduce the energy consumption in

urban areas.

Use of high reflective material on roof topUse light coloured roofs having an SRI (solar reflectance index)

of 50% or more. The dark coloured, traditional roofing finishes

have SRI varying from 5 - 20%. A good example of high SRI is

the use of broken china mosaic and light coloured tiles as roof

finish, which reflects heat off the surface because of high solar reflectivity and infrared

emittance, which prevents heat gain and thus help in reducing the cooling load from the

building envelope.

Thermal insulation for roof

Well insulated roof with the insulation placed on the external side is an effective measure to

reduce solar heat gains from the roof top. The insulated materials should be well protected

by water proofing.

For air conditioned spaces, Energy Conservation Building Code (ECBC) recommends the

thermal performance for external roof for all the five climate zones in India. Bangalore falls

under Moderate climate zone, the maximum U-value recommended by ECBC for moderate

climate zone is mentioned below:






Maximum U-factor of the overall assembly (W/m2K) Maximum U-factor of the overall assembly (W/m2K)


Insulation + cool roof

Along with lower U-value for roof, ECBC also recommends cool roof. Cool roofs are roofs

covered with a reflective coating that has high emissivity property which is very effective in

reflecting the suns energy away from the roof surface. These cool roofs are known to stay 10

C to 16 C cooler than normal roof under a hot summer day. This quality greatly helps in

reducing the cooling load that needs to be met by the HVAC system. Combination of

insulated roof along with cool roof has higher saving energy potential.

Figure 2.2: Broken china mosaic can be used asan external roof finish to reflect the incident solarradiation.

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External shading of roof

Shading of roof through design features like

pergola or solar photovoltaic panels help

reduce the incident direct solar radiation on

the roof surface. This in turn helps to reduce

the sol air temperature of the roof and

conduction gains in the space below. It is

observed using software simulations that

shading of roof has equal potential in

reducing the energy consumption by air

conditioning as that of an insulated roof.

Thermal properties of few building and insulating materials for reference are given below in

table 2.3.

Table 2.3: Thermal Properties of Building and Insulating Materials at Mean Temperature of 50deg.C

SL. NO. TYPE OF MATERIAL DENSITY THERMAL CONDUCTIVITY* SPECIFIC HEAT CAPACITY

(1) (2) (3) (4) (5)

Kg / m3 W / (m.K) KJ / (kg.K)

Building Materials

1. Burnt brick 1 820 0.811 0.88

2. Mud brick 1 731 0.750 0.88

3. Dense concrete 2 410 1.74 0.88

4. R.C.C. 2 288 1.58 0.88

5. Limestone 2 420 1.80 0.84

6. State 2 750 1.72 0.84

7. Reinforced brick 1 920 1.10 0.84

8. Brick tile 1 892 0.798 0.889. Line concrete 1 646 0.730 0.88

10. Mud Phuska 1 622 0.519 0.88

11. Cement mortar 1 648 0.719 0.92

12. Cement concrete 1 762 0.721 0.84

13. Cinder concrete 1 406 0.686 0.84

14. Foam slag concrete 1 320 0.285 0.88

15. Gypsum plaster 1 120 0.512 0.96

16. Cellular concrete 740 0.188 1.05

17. AC sheet 1 520 0.245 0.84

18. GI sheet 7 520 61.06 0.50

19. Timber 480 0.072 1.68

20. Timber 720 0.144 1.68

21. Plywood 640 0.174 1.76

22. Glass 2 350 0.814 0.88

23. Alluvial clay (40 percent sans) 1 958 1.211 0.84

24. Sand 2 240 1.74 0.84

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25. Black cotton clay (Madras) 1 899 0.735 0.88

26. Black cotton clay (Indore) 1 683 0.606 0.88

27. Tar felt (2.3 kg/m3) - 0.479 0.88

(Source, Handbook on Functional Requirements of buildings, SP:411987, BIS)

SL. NO. TYPE OF MATERIAL DENSITY THERMAL CONDUCTIVITY* SPECIFIC HEAT CAPACITY

(1) (2) (3) (4) (5)

Kg / m3 W / (m.K) KJ / (kg.K)

Insulating Materials




4. Foam glass 127.0 0.056 0.75

5. Foam glass 160.0 0.055 0.75

6. Foam concrete 320.0 0.070 0.92

7. Foam concrete 400.0 0.084 0.92

8. Foam concrete 704.0 0.149 0.92

9. Cork slab 164.0 0.043 0.96

10. Cork slab 192.0 0.044 0.96

11. Cork slab 304.0 0.055 0.96



14. Mineral wool (unbonded) 73.5 0.030 0.92



17. Resin bonded mineral wool 48.0 0.042 1.0018. Resin bonded mineral wool 64.0 0.038 1.00




22. Exfoliated vermiculite

(loose)

264.0 0.069 1.00

23. Asbestos mill board 1 397.0 0.249 0.88

24. Hard board 979.0 0.279 0.84

25. Straw board 310.0 0.057 1.42

26. Soft board 320.0 0.066 1.3027. Soft board 249.0 0.047 1.30

28. Wall board 262.0 0.047 1.30

29. Chip board 432.0 0.067 1.26

30. Chip board (perforated) 352.0 0.066 1.26

31. Particle board 750.0 0.098 1.30

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32. Coconut pith insulation

board

520.0 0.060 1.09

33. Jute fibre 329.0 0.067 1.09

34. Wood wool board


398.0 0.081 1.13

35. Wood wool board


674.0 0.108 1.13

36. Coil board 97.0 0.038 1.00

37. Saw dust 188.0 0.051 1.00

38. Rice husk 120.0 0.051 1.00

39. Jute felt 291.0 0.042 0.88

40. Asbestos fibre (loose) 640.0 0.060 0.84

2.2.3 Why is this required?Roof receives a significant amount of solar radiation round the year. As illustrated in Fig 1,

shows the intensity of solar irradiation is maximum on the horizontal plane which is the

roof. Conductance of heat from the roof can be very high if not insulated well.

This can result in increased cooling load if the space below is air conditioned or high

discomfort hours if the space below is naturally ventilated.

2.2.4 How is it beneficial?Treatment of roof in the form of roof insulation reduces cooling demand from air

conditioning and related energy consumption in air-condition and helps in maximizing

thermal comfort in non-air-conditioned spaces. Application of insulation on roof can bring

down energy consumption in air-conditioned spaces below roof.

Figure 2.3: Average daily Intensity of solar radiation incident on horizontal roof surface in Bangalore

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LCCA of conventional buildings and ECBC compliant roof

building

0

50

100

150

200

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Millions

Years

Cost(Rs)

Base case ECBC + cool roof case

Energy modeling has been carried out to quantify energy saving potential of roof insulation

and life cycle analysis has been carried out to calculate payback period for applying roof

insulation in a day use office air conditioned building. It has been observed that due to high

energy saving in single or double storey building after complying with ECBC thermal

performance of the roof, pay back period in Bangalore will be less than one year.

In naturally ventilated buildings, roof insulation brings positive impacts on t

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