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International Scholarly Research NetworkISRN Renewable EnergyVolume 2011, Article ID 484893, 11 pagesdoi:10.5402/2011/484893

Research Article

Suitable Glazing Selection for Glass-Curtain Walls inTropical Climates of India

M. C. Singh and S. N. Garg

Centre for Energy Studies, Indian Institute of Technology (Hauz Khas),New Delhi 110016, India

Correspondence should be addressed to M. C. Singh, [email protected]

Received 24 June 2011; Accepted 21 July 2011

Academic Editors: H. Boyer and G. Li

Copyright © 2011 M. C. Singh and S. N. Garg. This is an open access article distributed under the Creative Commons AttributionLicense, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properlycited.

How a glass-curtain wall affects the heating and cooling load of a building is analysed. The study includes five types of glazings,which include double-glazed clear glass, double-glazed low-e, and double-glazed solar control. The analysis is for three climates:composite (New Delhi), hot and dry (Jodhpur), and warm and humid (Chennai). An office building is chosen for analysis. Thestudy includes effect of glazed area, orientation, and that of climates, on annual energy consumption. It was found that energyconsumption increases linearly with the glazed area and minimum energy consumption is for north orientation. For types ofclimates considered in this study, a glass-curtain wall, made of solar control glazing (reflective), consumes 6–8% less energy thanthe standard window.

1. Introduction

In Indian metropolitan cities, a new trend in buildingconstruction is coming up: having front facade completelyglazed. Mainly, it is from aesthetic point of view, althoughlarge glazed area provides more natural light and therebyreduces artificial light requirement. A facade, having 90%of glazed area and 10% of frame area, is usually called aglass-curtain wall. Bouden [1] has analysed impact of glass-curtain walls on energy consumption for an office buildingin Tunisian climate. Seven different glass curtain walls, infour different orientations, with five different percentages ofglazed areas ranging from 20% to 90%, have been analysed.He has found that a glass-curtain wall made of one clear glassand other reflecting glass shows lower energy consumptionas compared to a standard size window (20% of area, singleglazed clear glass). Bansal et al. [2] have determined glazedarea, enough to keep a building thermally comfortable for3 winter climates of India. They have assumed direct gainthrough the glazed area absorbed by the building parts asfollows: 60% of the radiation by the floor and 8% by theceiling and each of the four walls. It has been found thatfor an uninsulated building (no insulation in walls/roof),

30% glazed area of south wall is sufficient for Delhi’scomposite climate. For insulated buildings, optimum glazedareas are: 10%, 20%, and 30% for New Delhi, Srinagar, andLeh, respectively. Hamdani and Ahmad [3] have analysedthe effect of window parameters on inside temperature ofthe building for climate of Baghdad in Iraq. Saridar andElkadi [4] have analysed the effect of different windowconfigurations on daylighting energy consumption in anoffice building at Beirut. A school building has been analysedin terms of energy consumption in Israel by [5], and it wasfound that the energy consumption can be reduced up to50% for high-performance school building. Johnson et al.[6, 7] have studied the annual energy consumption in anoffice building by using the different types of windows fordifferent climates of USA. Energy performance of a buildingis influenced by the window size and its orientation [8, 9].Energy efficient glazings reduce the heating and cooling loadof the buildings, allow natural daylight [10, 11], and providehuman thermal comfort [12]. The heating demands of thebuildings can be reduced by using the low-e windows andinsulation on walls and roof. Those buildings which havehigh internal gains and relatively large-glazed facade in southshow the lower demands of heating. Similarly, the cooling

2 ISRN Renewable Energy

13 mm82 mm

Inside Outside

13 mm 220 mm

Pla

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70 mm 13 mm

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ska

(b)

Figure 1: Construction details of (a) walls and (b) roof.

load of the buildings can be reduced by using the solarcontrol windows, and the requisite orientation in which itis minimum can be found [13, 14].

In India, large numbers of office buildings are con-structed with front facade completely glazed. How glass-curtain wall affects heating/cooling load of a building is notknown. In this work, the analysis has been carried out for awell-insulated office building. Effect of climatic conditions,glazings types, glazed areas, and orientations on annualenergy consumption has been analysed.

2. Input Data

Ten-year weather data (1991–2000) which include monthlymean hourly values of global solar radiation, diffuse solarradiation, relative humidity, and ambient temperature hasbeen procured from India Meteorological Department(IMD), Pune, and this measured data conforms to interna-tional standards. IMD Pune acts as the regional radiationcenter for Asia and maintains the international standards formeasurement of surface climate data.

A well-insulated office building with dimensions of12 m× 8 m× 3 m has been investigated. The insulation spec-ifications are taken as per Energy Conservation BuildingCode of India (ECBC-2006) [15]: U-values of its wallsand roof are 0.352 W/m2K and 0.409 W/m2K, respectively.Walls have been constructed with 220 mm of brick with13 mm of cement plaster on both sides. Roof has13 mmof cement plaster as innermost surface, 100 mm of RCC(Reinforced Cement Concrete), 75 mm of mudphuska (amixture of soil and rice husk), and 25 mm of brokentiles as the outermost surface. Insulation layer of expended

polystyrene has been provided on both walls as well as roof,immediately after the innermost layer of plaster (82 mmfor walls and 70 mm for roof). Details of walls and roofconstruction are shown in Figure 1. Thermal properties ofbuilding materials have been taken as per Bureau of Indianstandards (BIS) [16]. Working schedule has been assumedfrom 8 am to 6 pm, with Sunday as holiday. Internal gainsfrom occupants, lighting, and appliances during workinghours taken are: person 65 W; computer with monitor 140 W;lighting density 10.8 W/m2 [15]. The temperature has beencontrolled at 20◦C in winter and 25◦C in summer duringworking periods and at 18◦C and 30◦C, respectively, atother times. The ventilation rate considered is 1 ACH (airchanges per hour) during the working hours and 0.5 ACHat other times. This study includes three climatic conditionsof India: composite (New Delhi, 28◦35

′N, 77◦12

′E), hot and

dry (Jodhpur, 26◦18′N, 73◦01

′E), and warm and humid

(Chennai, 13◦00′N, 80◦11

′E). The climatic data of these

locations is shown in Figure 2. It includes monthly meanvalues of global radiation on horizontal surface, ambientair temperature, relative humidity, and wind speed. In mostpart of India (except few places at high altitudes), winteris mild and exists for two months only (December andJanuary) and mild heating is required. For air-conditionedbuildings, cooling is required for about 8 months, Marchto October. So this study is mainly from cooling point ofview. The emphasis is on the selection of glazing types andtheir optimum orientation, from cooling point of view. Newtypes of glass and coating are coming up in the market.With the increasing glazed area, the cooling load, in summer,always increases. In winter, it may lead to overheating whichnecessitates cooling.

ISRN Renewable Energy 3

Jan

Feb

Mar

Apr

May Jun

Jul

Au

g

Sep

Oct

Nov

Dec

(month)

0

2

4

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8

Sola

rra

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(kW

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(a)

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(month)

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(◦C

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(b)

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DelhiJodhpurChennai

(month)

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(month)

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dsp

eed

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(d)

Figure 2: Climatic data (monthly mean values) for three stations, (a) solar radiation, (b) ambient temperature, (c) relative humidity, and(d) wind speed.

Table 1: Different kinds of glass-curtain walls used in this study. The values of both U and g have been computed by WINDOW 5.0.

S. no. Glazing type Description Identity U (W/m2K) SHGC∗ (g-value)

1Double glazed, clear glass

window6 mm clear glass + 12 mm

air space + 6 mm clear glassClear-clear 2.95 0.73

2Double glazed, low-e

window6 mm low-e glass + 12 mmair space + 6 mm clear glass

Low-e1-clear 1.80 0.68

3Double glazed, low-e

window6 mm low-e glass + 12 mmair space+ 6 mm clear glass

Low-e2-clear 1.74 0.54

4Double glazed, solarcontrol (absorptive)

window

6 mm solar control(absorptive) glass + 12 mmair space + 6 mm clear glass

Solar control-abs 2.80 0.24

5Double glazed, solar

control (reflective) window

6 mm solar control(reflective) glass + 12 mm

air space + 6 mm clear glassSolar control-ref 1.95 0.10

∗Solar heat gain coefficient.

3. Methodology

Energy performance of the building has been investigatedby using TRNSYS 16 [17]. TRNSYS Type 56 is a transientsimulation module used for thermal analysis of buildings.The TRNSYS project model has three main features: weatherdata reader, solar radiation processor, and TRNBuild.Weather data reader reads the data from standard file formatsuch as TMY2 (Typical Meteorological Year version-2) andthen links it with the radiation processor. The solar radiationprocessor calculates the radiation on inclined surfaces. In

TRNBuild, user can create input data for buildings. Thisdata includes building envelope details such as walls, roof,floor, window, and operational behavior of the buildingsuch as heating and cooling schedules. Building has beentreated as an isolated single zone. Hourly simulations havebeen conducted over one year period, for each of the 3locations. This study includes five different types of windows(including low-e and solar control), six different glazed areasranging from 20% to 90% (expressed as percentage of wallarea). Table 1 describes the important properties of thesefive different glazings. Energy performance of each glazing


has been analysed for four different orientations. Energyconsumption of glass-curtain walls have been compared toan opaque wall with conventional glazed area (20%, doubleglazed clear glass window).

4. Results and Discussion

The analysis has been carried out for each of the five types ofglazings, by taking the effect of glazed area, orientation, andclimate on annual cooling and heating load.

4.1. Effect of Glazed Area. Effect of glazed area on building’scooling and heating load for all types of glazings and for allorientations is shown in Table 2(a) for Delhi, Table 2(b) forJodhpur, and Table 2(c) for Chennai. These three tables areexhaustive in the sense that all the details are shown here.Results are shown in unit floor area.

4.2. Delhi. Table 2(a) shows that as glazed area increases, theenergy consumption also increases, and this is already a well-known fact. In what proportion the energy consumptionincreases with the glazed area depends upon building type,glazing type, glazing orientation, and climate type, and thisis the subject matter of the present study. For this station andfor south orientation, the results are shown in graphical formin Figure 3(a). This figure shows that energy consumptionvaries almost linearly with the glazed area (a straight line canbe passed through tops of the bars for the same glazing). For10% increment in glazed area, the corresponding increase inenergy consumption is 15.3 kWh/m2yr for clear-clear glaz-ing, 15.1 kWh/m2yr for low-e1-clear glazing, 10.9 kWh/m2yrfor low-e2-clear glazing, 4.5 kWh/m2yr for solar control(absorptive), and 2.1 kWh/m2yr for solar control (reflective)glazing. The highest increment in energy consumption isfor clear-clear glazing, and the lowest increment is for solarcontrol (reflective) glazing.

4.3. Jodhpur. Results for this station are shown in Table 2(b)and Figure 3(b). Here, for 10% increase in glazed area,the corresponding increase in annual energy consumptionis 18.3 kWh/m2yr for clear-clear glazing, 17.5 kWh/m2yrfor low-e1-clear glazing, 12.8 kWh/m2yr for low-e2-clearglazing, 5.7 kWh/m2yr for solar control (absorptive) glazing,and 2.2 kWh/m2yr for solar control (reflective) glazing.

4.4. Chennai. Table 2(c) and Figure 3(c) show the effect ofglazed area on annual energy consumption for this station.If the glazed area is increased by 10%, the increase inannual energy consumption is 14.6 kWh/m2yr for clear-clear glazing, 13.8 kWh/m2yr for low-e1-clear glazing, and10.5 kWh/m2yr for low-e2-clear glazing, 5.4 kWh/m2yr forsolar control (absorptive) glazing, and 2.4 kWh/m2yr forsolar control (reflective) glazing.

4.5. Overheating in Winter. For Delhi station, when glazedarea exceeds 20% value, building gets overheated even inwinter and it requires cooling, subsequently. This holds trueparticularly for those glazings whose g-values are greaterthan 0.5. Such glazings let in solar radiation excessively, and

this results in overheating. For such curtain walls, on annualbases also, there is high requirement of heating/coolingenergy. For Delhi station, the results are shown in Table 3,and here, the glass-curtain forms the south facade of thebuilding. For the reference case, when the glazed area is 20%only (clear-clear glazing), during winter, there is no overheat-ing, and, hence, cooling energy requirement is almost nil.A small amount of heating, 0.3 kWh/m2yr, is required. Forsame case, during summer, the cooling energy requirementis 106.2 kWh/m2yr. But if the glazed area becomes 90%and the type of glazing remains the same (clear-clear),there is overheating in winter (resulting in cooling load of27.7 kWh/m2yr). This also results in increased cooling loadin summer (191.2 kWh/m2yr). Overheating in winter occursfor both types of low-e windows. Only for both types ofsolar control glazings, overheating in winter is very low ornegligible: being 2.5 kWh/m2yr for solar control (absorptive)glazing and 0.1 kWh/m2yr for reflective type solar controlglazing. During summer, low-e glazings (both types) showlow summer cooling load as compared to clear-clear glazing.The reduction in summer cooling load is very significant forboth types of solar control glazings: being 122.3 kWh/m2yrfor absorptive and 97.9 kWh/m2yr for reflective, respectively.

4.6. Effect of Orientation. Effect of orientation of glass-curtain wall on annual energy consumption is shown inTable 4. It is seen that south orientation corresponds tomaximum annual heating/cooling load and it is minimumfor north orientation. This fact holds good for all the stations.Building load for east and west orientation are almost equal(within 2% variation) for all types of glazings and for allclimates. Also energy requirement in east and west directionis slightly more (about 1-2%) than north orientation. Thereason is that: the beam radiation on east or west glazing issignificant and has almost equal value, while it is almost nilon north glazing. Figure 4 shows the results for Delhi station.Here, annual building load for 20% glazed area (referencecase, clear-clear) is normalized, so that the comparison ofother glazing types with the reference case becomes simple.In south orientation and with respect to reference case, aclear-clear glass-curtain wall results in 106% more energyrequirement. Increased energy requirement for other glass-curtain walls are 104% for low-e1, 69% for low-e2, 18%for solar control (absorptive), and −6% for solar control(reflective). The same trend is noticed for the other twostations also, Jodhpur and Chennai.

4.7.Effect of Climate.Effect of climate on comparison of glass-curtain wall with the reference case is shown in Figure 5. Foreach climate (or station), the annual energy consumption inthe reference case is normalized to 100 kWh/m2yr in order tomake the comparison simple. For composite climate of Delhiand with respect to reference case, a glass-curtain wall, madeof clear-clear glazing, low-e1 glazing, low-e2 glazing, andsolar control (absorptive) glazing shows 106%, 104%, 69%,and 18% more energy consumption respectively, while glass-curtain wall made of solar control (reflective) glazing shows6% less energy consumption. For dessert climate of Jodhpur,the corresponding values (in the same sequence) are 104%,


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50.

492

.592

.9

500.

014

1.2

141.

20.

013

8.1

138.

10.

012

5.5

125.

60.

210

5.4

105.

60.

494

.895

.2

650.

015

8.1

158.

10.

015

4.1

154.

10.

013

8.0

138.

00.

211

1.4

111.

60.

497

.197

.5

800.

017

5.9

175.

90.

017

2.2

172.

20.

015

1.2

151.

20.

211

8.1

118.

30.

410

0.2

100.

6

900.

018

5.3

185.

30.

018

1.9

181.

90.

015

8.4

158.

40.

212

1.2

121.

40.

410

1.3

101.

7

Wes

t

200.

210

8.2

108.

40.

210

6.6

106.

80.

210

2.2

102.

40.

495

.595

.90.

590

.490

.9

350.

112

5.1

125.

20.

112

2.3

122.

40.

211

3.9

114.

10.

410

0.1

100.

50.

592

.993

.4

500.

114

1.0

141.

10.

113

7.8

137.

90.

112

6.2

126.

30.

510

5.3

105.

80.

695

.996

.5

650.

115

8.9

159.

00.

115

5.0

155.

10.

113

8.0

138.

10.

511

1.7

112.

20.

698

.398

.9

800.

117

6.1

176.

20.

017

1.6

171.

60.

115

0.9

151.

00.

511

8.8

119.

30.

610

1.4

102.

0

900.

118

6.4

186.

50.

018

1.7

181.

70.

116

0.3

160.

40.

512

2.5

123.

00.

710

2.2

102.

9


(c)

Gla

zed

area

(%)

Cle

ar-c

lear

Low

-e1-

clea

rLo

w-e

2-cl

ear

Sol.c

ontr

ol-a

bsSo

l.con

trol

-ref

Hea

tin

glo

adC

oolin

glo

adTo

tal

load

Hea

tin

glo

adC

oolin

glo

adTo

tal

load

Hea

tin

glo

adC

oolin

glo

adTo

tal

load

Hea

tin

glo

adC

oolin

glo

adTo

tal

load

Hea

tin

glo

adC

oolin

glo

adTo

tal

load

Nor

th

200.

012

4.7

124.

70.

012

3.3

123.

30.

011

8.4

118.

40.

011

1.2

111.

20.

010

6.4

106.

4

350.

014

0.8

140.

80.

013

8.1

138.

10.

012

9.8

129.

80.

011

7.5

117.

50.

010

9.2

109.

2

500.

015

5.6

155.

60.

015

2.1

152.

10.

014

0.4

140.

40.

012

2.8

122.

80.

011

1.0

111.

0

650.

017

2.0

172.

00.

016

8.2

168.

20.

015

2.8

152.

80.

013

0.2

130.

20.

011

5.1

115.

1

800.

018

5.1

185.

10.

018

1.3

181.

30.

016

2.7

162.

70.

013

5.8

135.

80.

011

7.0

117.

0

900.

019

5.0

195.

00.

019

1.1

191.

10.

017

0.1

170.

10.

014

0.2

140.

20.

011

9.4

119.

4

Sou

th

200.

013

2.5

132.

50.

013

0.3

130.

30.

012

3.9

123.

90.

011

4.1

114.

10.

010

7.3

107.

3

350.

015

4.4

154.

40.

015

1.0

151.

00.

013

9.6

139.

60.

012

2.2

122.

20.

011

0.9

110.

9

500.

017

5.3

175.

30.

017

1.3

171.

30.

015

4.3

154.

30.

012

9.5

129.

50.

011

4.0

114.

0

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019

8.1

198.

10.

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3.4

193.

40.

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1.2

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8

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7.3

217.

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2.5

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50.

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5.7

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70.

014

6.6

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1.5

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5

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0.8

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80.

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6.3

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4.9

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00.

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5.8

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8

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3.6

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9.6

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018

6.4

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5

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50.

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9

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40.

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8

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4.6

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90.

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7

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019

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80.

018

7.0

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00.

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20.

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6.5

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50.

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2

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020

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00.

019

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20.

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4.6

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60.

014

0.3

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30.

011

8.6

118.

6


Delhi stationSouth orientation

Clear-clearLow-e1-clearLow-e2-clear

Sol.control-absSol.control-ref

908065503520

Glazed area (%)

0

50

100

150

200

250

An

nu

alen

ergy

con

sum

ptio

n(k

Wh

/m2yr

)

(a)

Jodhpur stationSouth orientation



908065503520

Glazed area (%)

0

50

100

150

200

250

300

An

nu

alen

ergy

con

sum

ptio

n(k

Wh

/m2yr

)(b)

Chennai stationSouth orientation



908065503520

Glazed area (%)

0

50

100

150

200

250

An

nu

alen

ergy

con

sum

ptio

n(k

Wh

/m2yr

)

(c)

Figure 3: Effect of glazed area on annual energy consumption. Five types of glazings are considered.

Table 3: Some glass-curtain walls results in overheating in winter. Delhi station, south orientation.

Glazing type Glazed area (%)Annual energy consumption (kWh/m2yr)

Summer Winter Annual

Cooling Heating Cooling

Clear-clear ( reference) 20 106.2 0.3 0.0 106.5

Clear-clear 90 191.2 0.0 27.7 218.9

Low-e1-clear 90 187.6 0.0 29.5 217.1

Low-e2-clear 90 161.4 0.0 18.8 180.2

Solar control-abs 90 122.3 1.0 2.5 125.8

Solar control-ref 90 97.9 2.0 0.1 100.0


Delhi



WestEastSouthNorth

Orientation

0

50

100

150

200

250

An

nu

alen

ergy

con

sum

ptio

n(n

orm

alis

ed,k

Wh

/m2yr

)

Figure 4: Effect of orientation on annual energy consumption. Four types of glass-curtain walls (90% glazed area) are compared withreference case (20% glazed area, clear-clear).

South orientation

Clear-clearClear-clearLow-e1-clear

Low-e2-clearSol.control-absSol.control-ref

ChennaiJodhpurDelhi

Station

0

50

100

150

200

250

An

nu

alen

ergy

con

sum

ptio

n

(nor

mal

ised

,kW

h/m

2yr

)

Figure 5: Effect of climate on comparison of glass-curtain walls with reference case.

102%, 69%, 18%, and −8%, respectively. For coastal climateof Chennai, the corresponding values are 74%, 71%, 48%,15%, and −6%, respectively. This shows that for compositeclimate, low-e1 glass-curtain wall consumes 104% moreenergy, while the same curtain wall, for coastal climate,consumes only 71% more energy. So climate has significanteffect on this comparison. It is also evident that, for all three

climates, curtain wall made of solar control glazing (reflec-tive) consumes 6%–8% less energy than the reference case.

5. Conclusions

As the glazed area increases, the annual energy consumptionincreases. It is seen that this energy consumption increases


Table 4: Effect of orientation of glass-curtain walls on building energy consumption.

StationAnnual energy consumption (kWh/m2yr)

Glazing type Glazed area (%) North South East West

Delhi

Clear-clear (reference) 20 98.0 106.5 99.8 98.8

Clear-clear 90 153.5 218.9 167.8 163.7

Low-e1-clear 90 149.2 217.1 163.2 160.5

Low-e2-clear 90 133.0 180.2 142.4 140.2

Sol.control-abs 90 113.9 125.8 112.2 112.8

Sol.control-ref 90 97.1 100.0 94.9 95.1

Jodhpur


Clear-clear 90 164.6 242.7 185.3 186.5

Low-e1-clear 90 162.2 239.8 181.9 181.7

Low-e2-clear 90 143.8 200.8 158.4 160.4

Sol.control-abs 90 120.4 140.6 121.4 123.0

Sol.control-ref 90 102.6 108.8 101.7 102.9

Chennai


Clear-clear 90 195.0 230.8 200.5 202.0

Low-e1-clear 90 191.1 226.3 195.9 197.2

Low-e2-clear 90 170.1 196.2 173.7 174.6

Sol.contro-abs 90 140.2 152.4 138.3 140.3

Sol.contro-ref 90 119.4 124.5 117.5 118.6

almost linearly with glazed area, for all types of glazings,for all climates, and for all orientations. For Delhi stationwith south orientation, 10% increment in glazed area leadsto more energy consumption of 15.3 kWh/m2yr for clear-clear glazing (highest increase) and 2.1 kWh/m2yr for solarcontrol (reflective) glazing (lowest increase).

Glass-curtail wall, with south orientation, results inmaximum heating/cooling load of a building, irrespective ofthe types of the glazings and the climates. Minimum energyconsumption is for north oriented glass-curtain wall. ForJodhpur and for double glazed low-e1 glass-curtain wall, it is239.8 kWh/m2yr for south orientation and 162.2 kWh/m2yrfor north orientation.

Climate has significant effect on comparison of glass-curtain wall with the reference case (south orientation). Aglass-curtain wall made of low-e1 glazing, with respect toto the reference case, consumes 103.9% more energy for thecomposite climate of Delhi and 71% more energy for coastalclimate of Chennai.

Out of five glazings analysed, a glass-curtain wall madeof solar control glazing (reflective) results in almost equalannual heating/cooling load of the building as the referencecase (clear-clear, 20% glazed area). It holds true for allorientations and for all climatic conditions analysed. Forsouth orientation and for 3 climates analysed, the glass-

curtain wall consumes 6%–8% less energy than the referencecase.

Acknowledgment

The first author is grateful to the Council for Scientificand Industrial Research (CSIR), New Delhi, for financialassistance.

References

[1] C. Bouden, “Influence of glass curtain walls on the buildingthermal energy consumption under Tunisian climatic condi-tions: the case of administrative buildings,” Renewable Energy,vol. 32, no. 1, pp. 141–156, 2007.

[2] N. K. Bansal, S. N. Garg, N. Lugani, and M. S. Bhandari,“Determination of glazing area in direct gain systems for threedifferent climatic zones,” Solar Energy, vol. 53, no. 1, pp. 81–90, 1994.

[3] N. I. Al-Hamdani and A. I. Ahmad, “Effect of windowparameters on indoor thermal environment of buildings,”Solar and Wind Technology, vol. 4, no. 1, pp. 71–75, 1987.

[4] S. Saridar and H. Elkadi, “The impact of applying recentfacade technology on daylighting performance in buildings ineastern Mediterranean,” Building and Environment, vol. 37, no.11, pp. 1205–1212, 2002.


[5] Y. V. Perez and I. G. Capeluto, “Climatic considerations inschool building design in the hot-humid climate for reducingenergy consumption,” Applied Energy, vol. 86, no. 3, pp. 340–348, 2009.

[6] R. Johnson, S. Selkowitz, F. Winkelmann, and M. Zentner,“Glazing optimization study for energy efficiency in com-mercial office buildings,” Tech. Rep. LBL–12764, pp. 1–10,Lawrence Berkeley National Laboratory, 1981.

[7] R. Johnson, S. Selkowitz, and R. Sullivan, “How fenestrationcan significantly affect energy use in commercial buildings,”Tech. Rep. LBL–17330, pp. 1–14, Lawrence Berkeley NationalLaboratory, 1984.

[8] H. Bulow-Hube, “The effect of glazing type and size onannual heating and cooling demand for Swedish offices,”in Proceedings of the Renewable Energy Technologies in ColdClimates, pp. 188–193, Montreal, Canada, 1998, Conference-46.

[9] M. L. Persson, A. Roos, and M. Wall, “Influence of windowsize on the energy balance of low energy houses,” Energy andBuildings, vol. 38, no. 3, pp. 181–188, 2006.

[10] M. Bojic and F. Yik, “Application of advanced glazing tohigh-rise residential buildings in Hong Kong,” Building andEnvironment, vol. 42, no. 2, pp. 820–828, 2007.

[11] M. M. Aboulnaga, “Towards green buildings: glass as abuilding element-the use and misuse in the gulf region,”Renewable Energy, vol. 31, no. 5, pp. 631–653, 2006.

[12] M. C. Singh, S. N. Garg, and R. Jha, “Different glazing systemsand their impact on human thermal comfort-Indian scenario,”Building and Environment, vol. 43, no. 10, pp. 1596–1602,2008.

[13] T. Frank, “Climate change impacts on building heating andcooling energy demand in Switzerland,” Energy and Buildings,vol. 37, no. 11, pp. 1175–1185, 2005.

[14] I. Singh, Heat transfer in fenestration systems and energysavings: buildings in India, Ph.D. thesis, Centre for EnergyStudies, Indian Institute of Technology, New Delhi, India,2002.

[15] Energy Conservation Building Code in India, Bureau of EnergyEfficiency, New Delhi, India, 2006.

[16] SP: 41 (S&T), Hand Book of Functional Requirements ofBuildings, Bureau of Indian Standards (BIS), New Delhi, India,1987.

[17] TRNSYS, “A transient system simulation program,” Tech. Rep.W E-53706, pp. 1–82, Solar Energy laboratory, University ofWisconsin, Madison, Wis, USA, 2004.

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