Learning for High Performance Buildings

Presentation byMili Majumdar

Associate DirectorSustainable Building Science

TERI15th May,2009

1

Defining High Performance (Commercial) Buildings in India

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Defining high performance buildings: energy wise

• A high-performance building is one with a substantially better energy, economic and environmental performance than standard practice, resulting in a structure that:

• Is energy efficient;• Saves money and natural resources;• Is a healthy place to live and work; and• Has a relatively low impact on the environment.

Setting the parameters

• Energy performance index (kWh/sqm/year)• Thermal and visual comfort

• Temperature, Relative Humidity, Air movement• Illumination level maintained

Indoor design conditions for air conditioned Indoor design conditions for air conditioned buildings (comfort conditions)buildings (comfort conditions)

Adaptive comfort in Non AC buildings (National building code)

• Indians have a higher tolerance threshold for heat and cold because we live in non AC homes and in hotter climates as compared to the US.

• Adaptive comfort is now being given priority internationally as well, so as to reduce AC energy requirement, which comprises the highest percentage in commercial and residential building energy consumption

Table 9: Desirable Wind Speeds (m/s) for Thermal Comfort Conditions Clause 5.2.3.1

Dry Bulb Temperature

Relative humidity percentages

oC 30 40 50 60 70 80 90 28 29 0.06 0.19 30 0.06 0.24 0.53 0.85 31 0.06 0.24 0.53 1.04 1.47 2.10 32 0.20 0.46 0.94 1.59 2.26 3.04 33 0.77 1.36 2.12 3.00 34 1.85 2.72 35 3.20

None Higher than those acceptable in practice

Energy Performance Indices (National Green Building Rating System “GRIHA”)

These are merely the ‘passing marks’ that a building must attain to get graded. One needs to significantly cross this level to get higher marks under GRIHA. Every 10% reduction below the mentioned level yields two additional points.

Energy Performance Indices for rating by Bureau of Energy Efficiency:Climate Zone – Composite: BEE star rating for day use buildings

Table of BEE Star rating for Office Building more than 50 % Air Conditioned Built-up Area

Climate Zone - Composite

0

165

140

115

165

140

115

90below 90

190

020406080

100120140160180200

1 Star 2 Star 3 Star 4 Star 5 StarStar Label

EPI (

kwh/

sqm

/yea

r)

Table of BEE Star rating for Office Building less than 50% Air Conditoned Built-up Area

Climate Zone - Composite

0

8070

6050

7060

5040

below 40

0102030405060708090

1 Star 2 Star 3 Star 4 Star 5 Star

Star Label

EPI (

kwh/

sqm

/yea

r)

190-90 kWh/ sq m/annum /year

80-40 kWh/ sq m/annum /year

Toolkits available

• Energy Conservation Building Code 2007• National Building Code 2005• Knowledge of traditional architectural systems

which are proven to provide thermal comfort at minimal energy requirement

>250 kWh/m2-yr

<140 kWh/m2-yr/

47 kWh/m2-yr/

Trends : Shift from high “energy performance” “low thermal comfort buildings” to “over cooled energy

guzzlers”

Blend traditional systems with technology to arrive at optimum energy efficient solution

Study conducted by TERI to define roadmap for High Performance Buildings

in India

Passive low energy strategies

Human

Comfort

Energy

efficiency

High Performance Commercial Buildings in India

=++

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Parameters Conventional building

Passive low energy building

Lighting design

Lighting power density 15-20W/m2

Lighting power density lower than 15W/m2

No lighting controls Occupancy sensors & dimming controls

No daylight integration

Daylight and artificial light integration

Visual comfort maintained as per NBC 2005

Visual comfort maintained as per NBC 2005

Parameters Conventional building

Passive low energy building

Design Features

Long facades East – West

Long facades North -South

No shading Shading of East, West façade, shaded windows

Single glazed windows

Mix of single & double glazed windows.

Parameters Conventional building Passive low energy building

Air conditioning system

No passive cooling strategies

Circulation areas naturally ventilated

Reciprocating chillers used

Screw & centrifugal chillers used

Lower CoP of chiller Higher CoP of chillerSqmt./TR 9 – 15 Sqmt./TR 32 – 42Thermal comfort maintained as per NBC 2005

Thermal comfort maintained as per NBC 2005

Energy and comfort performance of existing commercial buildings

Parameters Conventional building Passive low energy building

Energy Performance

Energy Performance Index (kWh/m2/year) for different climate zones:

•Warm Humid- 236 (10 hrs)•Moderate – 309 (10 hrs)•Composite – 231(10 hrs)•Cold – 419 (24 hrs)

Energy Performance Index (kWh/m2/year) for different climate zones:

•Warm Humid- 218 (24 hrs)•Moderate – 76 (10 hrs)•Composite – 146(10 hrs)•Cold – 70 (10 hrs)

7

7

Shaded Windows Optimized WWR

Shaded East West Facades

Courtyards

Energy Audit of buildings

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Validated models used to carry out parametric analysis and evaluate impact of low energy/passive and ECBC (Energy Conservation Building Code) measures on these buildings

Validation of energy model

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Energy models developed and validated/calibrated with audit results

Wipro, Warm-humid climate

HUL, Moderate climate

Impact of LowEnergy Strategies

Favorable orientation, Roof shading, window shading 10

ECBC Window SHGC = 0.25U-factor = 3.3 W/m2-0C

ECBC Envelope

Concrete slab

Insulation

finishes

11

ECBC HVAC ECBC lighting

Impact of Energy Conservation Building Code

Impact of low energy strategies, ECBC features and combined EE measures in Warm & Humid climate

0

100200

300400

500

600700

800900

1000

Cooling Load(TR) Load(kW) kWh*10000

Existing case Low energy strategies ALL ECBC Existing best case

437 TR

873 kW

823 kW

363 TR 338

TR 305TR

674kW

544 kW

17%23%

30%

6%

23%

38%

Impact of low energy strategies, ECBC features and combined EE measures in Moderate climate

0

100

200

300

400

500

600

700

Cooling Load(TR) Load(kW) kWh*10,000

Existing case Low energy strategies All ECBC Existing Best case

5%

21%35%

364 EPI

342 EPI

260 EPI

194 EPI

413 TR

289 TR

384 TR

271 TR

663kW

484kW

431kW

336 kW 97

EPI 75EPI 64

EPI 55EP

30%7%

34%

27%

35%

49%

18%27%

34%

• Climate responsive design features should be in tandem with ECBC recommendations to realize maximum saving potential in buildings.

•Impact of low energy strategies(N-S Orientation, shaded walls and roof, windows on N-S facades, natural ventilation) on Energy Performance Index in warm –humid climate zone is 5%, in Moderate climate zone it is 18%.

•Impact of ECBC measures (LPD, Envelope, HVAC systems)) on Energy Performance Index in warm –humid climate zone is 21%, in Moderate climate zone it is 27%.

•Combined impact is 35% for warm humid and 34% for moderate climate

Learning………

Apply Integrated design approach for maximum benefit1

Wall optimization

Daylight optimization

HVAC

Building Energy Performance

Bioclimatic design

Artificial lighting

Roof optimization

Fenestration optimization

Daylight integration Low energy strategies

Client expresses requirement. Project brief prepared.

Architect prepares drawings on basic design, façade, etc.

No passive features, high glass areas, no regional considerations

HVAC

Thumb-rule design

High factor of safety

Over-designed

No Energy Efficiency

Final drawings are collated by the architect

Construction drawings are prepared

Contractor executes project as per drawings.

Lack of coordination leads to time overruns as well as wastage of materials

Interior design is carried out by separate individuals and contractors based on individual requirements, which may or may

not be in line with architectural / engineering design

Electrical

Thumb-rule design

High factor of safety

Over-designed

No Energy Efficiency

Plumbing

Thumb-rule design

High factor of safety

Over-designed

No water Efficiency

• Lack of coordination between aspects since no common goal

• Every aspect leads to additional costs

• Maximum wastage of materials and resources

• Poor visual and thermal comfort environment at a very high operational cost

Apply trade-off approach to make choice of ECMs

• Apply trade off approach(use computer simulation tools to make investment decisions on ECMs)• For maximum value for money spent it is advisable to

trade off between several ECMs• Use of fixed shading can partly offset cost of high

performance glass• Use of cool roof can partly offset cost of roof insulation• Usage of lower light power densities can offset cost of

high efficiency fixtures• Usage of fresh air pre cooling techniques can reduce

chiller sizing

2

Energy optimisation for office building in Bihar (2300 sq m)

Description TR

%Reduction in energy

consumption over base case

EPI(kWh/sqm-

yr)

1 Base Case 113 - 344

2 Alternative 1 + Orientation 107 3 332

3 Alternative 2 + Shading 89 15 287

4 Alternative 3 + WWR 83 18 273

5 Alternative 4 + ECBC Glass 79 23 256

6 Alternative 5 + ECBC Roof 59 33 213

7 Alternative 6 + Reflective Roof 58 34 210

8 Alternative 7 + ECBC Wall 53 38 194

9 Alternative 8 + LPD 49 49 166

10 Alternative 9 + Improved Chiller 49 60 122

Optimise glazing design (size, shading glass type)

Study done by Skidmore, Owning and Meryll on impact of glass area on energy consumption

Effect of Increased Glass on Energy Performance

100.0%

119.80%

140.80%

162.60%

186.50%

0.0%

20.0%

40.0%

60.0%

80.0%

100.0%

120.0%

140.0%

160.0%

180.0%

200.0%

Base Design 0+WWR 50% 6+WWR 60% 7+WWR 70% 8+WWR 80%

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0102030405060708090

100

0 10 20 30 40 50 60 70 80 90 100Lig

ht T

ran

smit

tan

ce

WWR

Variation of Window Wall Ratio with Light Transmittance of glass to meet Bureau of Indian Standard Daylight Factor

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Get involved

• Question the assumptions/design norms• Develop a feel of the numbers (check figures)

• Lighting power density (ECBC limits are on higher side)

• Cooling demand (sqm/TR)…for High performance buildings can go up to 30-35 sqm/TR

• Indoor design conditions (each degree change can save 3-5% of cooling demand)

• Outdoor fresh air loads

4

Expanded comfort band: key to reducing energy demand

Comfort band

TERI University: Usage of multiple low energy cooling techniques: (thermal storage, earth air tunnel, Variable refrigerant flow system)

The Doon School: Master’s houses

Monitored winter temperature profiles

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Dates

Tem

pera

ture

MF

HK

MF

HK

MF

HK

MF

HK

MF

HK

MF

HK

Max

Min

Temperature differential of about 4-6 degree over conventional houses in peak winter times

Consider life cycle costs in place of initial costs5

LIFE CYCLE COST CALCULATIONS FOR IIT KANPUR OVER 25 YEARSInitial Investment Costs for:IIT Kanpur building: Rs. 6 croresConventional Building: Rs. 5 croresInitial Incremental Investment Costs for IIT Kanpur Green Building: Rs. 1 crores

Energy Savings of IIT Building over Conventional Building in 25th year: Rs.3.5 croresOM&R Savings of IIT Building over Conventional building in 25th year: Rs. 2,09,032 Net Savings in the 25th year of operation: Rs.2.5 crores

(Net savings = Energy and OM&R Savings- Incremental Investment- Replacement Costs Difference)

The Payback is achieved in the 7th year of operation of the IIT Kanpur building, with the Net Savings becoming positive and Savings to Investment Ratio = 1.059.

SENSITIVE PARAMETERS1. Discount Rate: When changed from the 10%

to 18%, the payback period increases from 7 years to 10 years and the savings in the 25th

year decrease substantially from Rs. 2.43 crores to Rs. 63.01 lacs.

2. Escalation rate: When changed from 7.6% to 12%, the savings in the 25th year almost get doubled with the payback period decreasingby an year.

3. Energy Charges: When the energy charges are changed from Rs.6/ kWh to Rs. 3/kWh, the payback period increases from 7 to 14 years and the net savings in the 25th year reduce to Rs. 67 lacs from Rs. 2.43 croreswhile an increase in the energy charges leads to reduction in payback period and double the net savings.

Educate users6

Thank You

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