IMPACT OF INTERNAL & EXTERNAL FACTORS IN BUILDING …

IMPACT OF INTERNAL & EXTERNAL FACTORS IN BUILDING ENERGY CONSUMPTION IN SRILANKA

Chapter 3 Theoretical background

3.1 Literature review [2,6]

In order to achieve objective of this research, it is necessary to develop basic idea of related theories. This chapter is targeted to provide the reader to get idea how theories are developed.

Qroot or

ceiling

Oiioor

Fig 3.1 Room heat gain component

3.1.1 The room cooling load

The room cooling load is the rate at which heat must be removed from the room air to maintain is at the design temperature and humidity.

H. Ruchira Daminda Perera Page 6 October 2010


3.1.2 The cooling load calculations

The cooling load calculation procedures that will be explained here is called the CLF/CLTD method. This procedure is relatively easy to understand and use. The CLF /CLTD method can be carried out manually or by using a computer.

3.1.3 Room heat gains[10]

The heat gain components that contribute to the room cooling load consist of the following table 3.1.

Type External Heat Gains Internal Heat gains

Separate Class

Sensible Gains

I Conduction through exterior walls. Roofs, and Glass

IV Lighting VII Heat from infiltration of outside air through openings

Sensible Gains

11 Conduction through interior partitions, ceilings, and floors

V People

Sensible Gains

III Solar radiation through Glass

VI Equipment

Sensible Gains

IV Lighting

Sensible Gains

VI Equipment Latent Gains

VI Equipment Latent Gains

V People

Table 3.1- Heat components of building

It is also convenient to arrange the heat gains into a different set of two groups. Those from sensible and latent heat gains. Sensible heat gains result in increasing the air temperature: Latent heat gains are due to addition of water vapor, thus increasing humidity.

3.1.3.1 Conduction through exterior structure

The cooling loads caused by conduction heat gains through exterior roof, walls and glass are each from the following equations (3.1).

H Ruchira Daminda Perera Page 7 October 2010


Q=U* A *CLTD c (3.1)

Where

Q= Cooling Load for roof, walls, or glass BTU/hr

U=Overall heat transfer coefficient for roof, wall, or glass, BTU/hr-ft2 - F

A =area of Roof, wall, or glass, ft

CLTD c ^corrected Cooling load temperature difference, F .

The cooling load temperature difference (CLTD) is not the actual temperature difference between the outdoor and indoor air. It is modified value that accounts for the heat storage /time lag effects.

Table 3.2, 3.3 and table 3.4 are based on the following conditions. Hr of Maxl- Mini- Maxi- Drfttr-

Sotar Tlma, h mum mum mum aftca 0100 0300 03000400 0900 0600 0700 0000 0900 10001100 1200 1300 1400 1500 1600 1700 1000 1900*300 21002200 2300 Z400 CLTO CUO CUB CLTD

North Latttud* Wall Facing

N 14 14 14 13 13 3 12 12 II 11 10 10 10 10 10 10 11 11 12 12 13 13 14 14 2 10 14 4 NE 19 19 19 18 17 7 16 15 15 15 15 IS 16 16 17 18 IB 18 19 19 20 20 2 0 ' 20 23 15 20 5 E 24 24 23 23 22 2 t 20 19 19 18 19 19 20 21 22 23 24 24 25 25 25 25 25 25 22 18 25 7

SE 24 23 2.1 22 21 2 0 20 t9 18 18 18 18 18 (9 20 21 22 2.1 23 24 24 24 24 24 22 18 24 6 S 20 20 19 19 18 1 8 17 16 16 15 14 14 14 14 15 16 17 18 19 19 20 20 20 23 14 20 6

SW 25 25 25 24 24 2 3 22 20 19 19 18 17 17 17 17 18 19 20 23 24 25 25 24 17 25 8 W 27 27 26 26 25 2 4 24 23 22 21 20 19 19 18 18 18 18 19 20 22 33 25 26 26 1 18 27 9

NW I I 21 21 20 20 1 9 19 18 17 16 16 15 15 14 14 14 15 IS 16 17 18 19 20 21 1 14 21 7

15 14 14 )3 12 11 I) 10 9 9 » 8 9 19 18 17 16 13 14 13 12 12 13 14 15 16 23 22 21 20 18 17 16 15 15 15 17 19 21 23 22 21 20 18 17 16 IS 14 14 15 16 IB 21 20 19 18 17 IS 14 13 12 t i 11 II II

- - ' • 22 21 19 18 16 IS 14 14 13 24 23 21 19 18 17 16 15 14 19 18 17 15 14 13 12 12 12

25 24 27 26

23 22 21 20

9 9 10 11 12 13 14 14 15 15 15 17 16 19 19 20 20 21 21 21 20 20 22 24 25 26 26 27 27 26 26 25 24 30 21 23 24 25 26 26 26 26 25 2* 12 14 IS 17 19 20 21 22 22 22 21 13 14 IS 17 20 22 25 27 28 28 28 14 14 15 17 19 22 25 27 29 29 30 II 12 12 13 IS 17 19 21 22 23 23

21 14 26 12 23 11 22 11 24 13 28 15 24 14 30 16

N IS 14 13 12 11 10 9 8 B 7 7 8 8 9 10 12 13 14 15 16 17 17 17 16 22 7 17 10 NE 19 17 16 14 13 t l 10 10 11 13 IS 17 19 20 21 22 22 23 23 23 23 22 21 20 20 10 23 13 E 22 21 19 17 IS 14 12 12 14 16 19 22 25 27 29 29 30 30 30 29 26 27 26 24 18 12 30 18

SE 22 21 19 17 15 14 12 12 12 13 16 19 22 24 26 28 29 29 29 29 28 27 26 24 19 12 29 17 S 21 19 18 16 15 13 12 10 9 9 9 10 11 14 17 20 22 24 25 26 25 25 24 23 20 9 26 17

SW 29 27 25 22 20 16 16 IS 13 12 11 11 11 13 15 18 22 26 29 32 33 33 32 31 22 11 33 22 W 31 29 27 25 22 20 18 16 14 (3 12 (2 12 13 (4 (6 20 24 29 32 35 35 35 33 22 12 35 23

NW 25 23 21 20 18 16 14 13 11 10 10 10 10 11 12 13 15 18 22 25 27 27 27 26 22 10 27 17

N 15 13 12 10 9 7 6 6 6 6 6 7 8 10 12 13 15 17 18 19 19 19 18 16 21 6 19 13 NE (7 15 13 11 10 8 7 8 10 14 17 20 22 23 23 24 24 25 25 24 23 22 20 18 19 7 25 IB E 19 17 15 13 11 9 8 9 12 17 22 27 30 32 33 33 32 32 31 30 28 26 24 22 16 8 33 25

SE 20 17 15 13 11 10 B B 10 13 17 22 26 29 31 32 32 32 31 30 28 26 24 22 17 8 32 24 S 19 17 15 13 11 9 8 7 6 6 7 9 12 16 20 24 27 29 39 29 27 26 24 22 19 6 29 23

sw 28 25 22 !9 16 14 12 10 9 8 8 8 10 12 16 21 27 32 36 38 3B 37 34 31 21 8 38 30 w 31 27 2A 21 18 15 13 11 10 9 9 9 10 11 14 18 24 30 36 40 41 40 38 34 21 9 41 32

NW 25 22 19 17 14 12 10 9 8 7 7 8 9 10 12 14 18 22 27 31 32 32 30 27 22 7 32 35

5 9 13 20 24 23 25 6 II IB 26 33 36 38 5 8 12 19 . 2 5 31 35

16 14 20 3 22 19

17 13 16 4 26 22 22 18 IS 12 10 25 21 17 14 11 20 17 14 II 9

13 IS 17 19 20 21 23 26 26 26 26 26 25 24 22 19 37 36 34 33 32 30 28 25 22 20 17 13 5 38 33 37 37 36 34 33 31 28 26 23 20 17 15 5 37 32 24 29 32 34 33 31 29 26 23 20 17 17 3 34 31 IB 24 32 38 43 45 44 40 35 30 26 19 5 45 40 14 20 27 36 43 49 49 45 40 34 29 20 6 49 43 13 16 20 26 32 37 38 36 32 28 24 20 5 38 33

4 ID 19 28

9 11 14 17 19 30 29 28 27 27 44 45 43 39 36 36 41 43

" 20 27

21 22 23 27 27 26

32 30 27 24 21 17 IS 12 12 42 39 36 34 31 28 25 21 18 15 12 13

5 8 I) 17 26 35 6 8 11 14 20 38 5 8 10 13 IS 21

39 38 35 44 SO 53 39 49 57 37 33 42

31 26 22 18 IS 12 16 52 45 37 28 60 34 43 34 46 43 33 28

23 23 30 29 45 43 43 41

27 21 19 3 60 37 22 18 19 2 46 44

2 7 a 9 12 IS 18 21 23 24 24 25 26 22 IS 11 9 27 36 39 35 30 26 26 27 27 26 25 22 18 14 II

11 31 47 54 55 50 40 33 31 30 29 27 24 19 15 12 5 18 32 42 19 51 48 42 36 32 30 27 24

5 12 22 31 39 45 12 16 26 38

37 31 25 20 15 12 10 8 5 14 63 61 52 37 24 17 13 10 S 16

8 11 13 19 27 41 56 67 72 67 48 29 8 II IS 18 21 27 17 47 55 55 41 25 18 0 55 55

Reprinted wiih ptnmuion (mm the I9S9 ASHRAE Hamfbtnt—Funclimriitatt.

Table 3.2 -Cooling load temperature difference (CLTD) for calculating load from walls


S I P ' IMPACT OF INTERNAL & EXTERNAL FACTORS IN BUILDING ENERGY CONSUMPTION IN SRILANKA

U-value,

Hour of

Maxi- Mini- Maxi- Differ-Roof Description of Weight. BTU Solar Time mum mum mum ence No Construction lb/ft1 h.frVF 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 CLTD CLTD CLTD CLTD

Without Suspended Ceiling

1 Steel sheet with l-in. 7 0.213 l -2 -3 -3 -5 -3 6 19 34 49 61 71 78 79 77 70 59 45 30 18 12 8 5 3 14 -5 79 84 (or 2-in.) insulation (8) (0.124)

2 l-in. wood with l-in. 8 0.170 6 3 0 -1 -3 -3 -2 4 14 27 39 52 62 70 74 74 70 62 51 38 28 20 14 9 16 -3 74 77 insulation

3 4-in. lightweight 18 0.213 9 5 2 0 -2 -3 -3 1 9 20 32 44 55 64 70 73 71 66 57 45 34 25 18 13 16 -3 73 76 concrete

4 2-in. heavyweight concrete with l-in. 29 0.206 12 8 5 3 0 -1 -1 3 11 20 30 41 51 59 65 66 66 62 54 45 36 29 22 17 16 -1 67 68 (or 2-in.) insulation (0.122)

5 l-in. wood with 2-in. 9 0.109 3 0 -3 -4 -5 -7 -6 -3 5 16 27 39 49 57 63 64 62 57 48 37 26 18 11 7 16 -7 64 71 insulation

6 6-in. lightweight 24 0.158 22 17 13 9 6 3 1 1 3 7 15 23 33 43 51 58 62 64 62 57 50 42 35 28 18 1 64 63 concrete

i 2.5-in. wood with 13 0.130 29 24 20 16 13 10 7 6 6 9 13 20 27 34 42 48 53 55 56 54 49 44 39 34 19 6 56 50


9 4-in. heavyweight concrete with 1 -in. 52 0.200 25 22 18 15 12 9 8 8 10 14 20 26 33 40 46 50 53 53 52 48 43 38 34 30 18 8 53 45 (or 2-in.) insulation (52) (0.120)

10 2.5-in. wood with 13 0.093 30 26 23 19 16 13 10 9 8 9 13 17 23 29 36 41 46 49 51 50 47 43 39 35 19 8 51 43 2-in. ins.

11 Roof terrace system 75 0.106 34 31 28 25 22 19 16 14 13 13 15 18 22 26 31 36 40 44 45 46 45 43 40 37 20 13 46 33 12 6-in. heavyweight

concrete with l-in. 75 0.192 31 28 25 22 20 17 15 14 14 16 18 22 26 31 36 40 43 45 45 44 42 40 37 34 19 14 45 31 (or 2-in.) insulation (75) (0.117)

13 4-in. wood with l-in. 17 0.106 38 36 33 30 28 25 22 20 18 17 16 17 18 21 24 28 32 36 39 41 43 43 42 40 22 16 43 27 (or 2-in) insulation (18) (0.078)

H. Ruchira Daminda Perera

Table 3.3- Cooling load temperature difference (CLTD) for flat roof

October 2010

(i) Indoor temperature is 78 F DB

(ii) Outdoor average temperature on the design day is 85 F DB.

(iii) Date is July 21 ST

(iv) Location is 40 N latitude

If the actual condition differs from any of the above, The CLTD must be corrected as follows.

Page 9


Hour of

(/•value, Maxi Mini Maxi DifferRoof Description of Weight, BTU Solar Time mum mum mum ence No Construction lb/ft2 h«rtVF 1 2 3 4 5 6 7 8 0 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 CLTD CLTD CLTD CLTD

With Suspended Ceiling 1 Steel sheet wiih l-in. 9 0.134 2 0 -2 -3 -4 -4 -1 9 23 37 50 62 71 77 78 74 67 56 42 28 18 12 8 5 15 -4 78 82

(or 2-in.) insulation (10) (0.092) 2 l-in. wood with l-in. ins. 10 0.115 20. IS 11 8 5 3 2 3. 7 13 21 30 40 48 55 60 62 61 58 51 44 37 30 25 17 2 62 60 3 4-in. lightweight 20 0.134 19 14 10 7 4 2 0 0 4 10 19 29 39 48 56 62 65 64 61 54 46 38 30 24 17 0 65 65

concrete 4 2-in. heavyweight

concrete with l-in. 30 0.131 28 25 23 20 17 15 13 13 14 16 20 25 30 35 39 43 46 47 46 44 41 38 35 32 18 13 47 34 insulation

5 l-in. wood with 10 0.083 25 20 16 13 10 7 5 5 7 12 18 25 33 41 48 53 57 57 56 52 46 40' 34 29 18 5 57 52 2-in. ins

6 6-in. lightweight 26 0.109 32 28 23 19 16 13 10 8 7 8 II 16 22 29 36 42 48 52 54 54 54 47 42 37 20 7 54 47 concrete

7 2.5-in. wood with 15 0.096 34 31 29 26 23 21 18 16 15 15 16 18 21 25 30 34 38 41 43 44 44 42 40 37 21 15 44 29 l-in. insulation


9 4-in. heavyweight concrete 53 0.128 30 29 27 26 24 22 21 20 20 21 22 24 27 29 32 34 36 38 38 38 37 36 34 33 19 with l-in. (or 2-in.) ins. (54) (0.090)

10 2.5-in. wood with 15 0.072 35 33 30 28 26 24 22 20 18 18 18 20 22 25 28 32 35 38 40 41 41 40 39 37 21 2-in. ins

II Roof terrace system 77 0.082 30 29 28 27 26 25 24 23 22 22 22 23 23 25 26 28 29 31 32 33 33 33 33 32 22 22 33 11 12 6-in. heavyweight

concrete with l-in. 77 0.125 29 28 27 26 25 24 23 22 21 21 22 23 25 26 28 30 32 33 34 34 34 33 32 31 20 21 34 13 (or 2-in.) insulation (77) (0.088)

13 4-in. wood with l-in. 19 0.082 35 34 33 32 31 29 27 26 24 23 22 21 22 22 24 25 27 30 32 34 35 36 37 36 23 21 37 16 (or 2-in.) insulation (20) (0.064)

Table 3.4-Cooling load temperature difference (CLTD) for flat roofs continue

Paee 10 October 2010 H. Ruchira Daminda Perera r a 6


CLTD c = CLTD +LM+ (78-t R) + (ta-85) ....(3.2)

Where

CLTD c = Corrected value of CLTD, in F

CLTD= temperature from Table 3.3 & 3.4

LM =Correction for latitude and month, from table

tp; = Room temperature, F

ta = Average outside on design day, F

The temperature t„ can be found as follows:

t a=t0-(D.R)/2 (3.3)

Where

to=Outside design dry bulb temperature, F

Both to and PR (the daily temperature range) are found in Table.

3.1.3.2 Conduction through interior structure

The heat that flows from interior unconditioned spaces to the conditioned space through partitions, floors, and ceilings can be found from Equations 3.4 [7]

Q=U*A*TD (3.4)

Where

Q= heat gain (cooling load) through partition, floors, or ceiling, BTU/hr

U=overall heat transfer coefficient for partition, floor, or ceiling, BTU/hr-ft2

A=Area of partitions, floor, or ceiling, ft2

TD= temperature difference between unconditioned and conditioned space, F.



3.1.3.3 Solar radiation through glasses

Radiant energy from the sun passes through transparent materials such as glass and becomes a heat gain to the room. Its value varies with time, orientation, shading and storage effect. The solar cooling load can be found from the following equation[3.5]

Q=SHGF*A*SC*CLF.... (3.5)

Where,

Q= Solar radiation cooling load for glass, BTU/hr

SHGF=maximum solar heat gain factors, BTU/hr-ft2,

A= Area of Glass, ft2

SC=Shading Coefficient

CLF=Cooling load factor for glass

The maximum solar heat gain factor (SHGF) is the maximum solar heat gain through single clear glass at a given month; orientation, and latitude, values are shown in table 3.5. For the 2 1 s t day of each month.



NNE/ NE/ ENE/ E/ ESE/ SE/ SSE/ N NNW NW WNW W WSW SW SSW s HOR

Jan. 29 29 48 138 201 243 253 233 214 232 Feb. 31 31 88 173 226 244 238 201 174 263 Mar. 34 49 132 200 237 236 206 152 115 284 Apr. 38 92 166 213 228 208 158 91 58 287 May 47 123 184 217 217 184 124 54 42 283 June 59 135 189 216 210 173 108 45 42 279 July 48 124 182 213 212 179 119 53 43 278 Aug. 40 91 162 206 220 200 152 88 57 280 Sep. 36 46 127 191 225 225 199 148 114 275 Oct. 32 32 87 167 217 236 231 196 170 258 Nov. 29 29 48 136 197 239 249 229 211 230 Dec. 27 • 27 35 122 187 238 254 241 226 217

24' N. Lat NNE/ NE/ ENE/ E/ ESE/ SE/ SSE/

N NNW NW WNW W WSW SW SSW S HOR

36* N. Lat

Jan. Feb. Mar. Apr. May June July Aug. Sep. Oct. Nov. Dec.

27 30 34 37 43 55 45 38 35 31 27 26

27 30 45 88

117 127

41 80

124 195

128 190 165 220

234 228 218

184 214 212

159 209 178 214

116 176 210 87 156 203 42 119 185

79 159 42 126 29 112

31 27 26

213 220 222 211 187 180

240 253 241 244 243 213 237 214 212 169 190 132 179 117 185 129 204 162 225 206 237 235 236 249 234 247

168 107 67 55 65

103 163 207 237 247

227 214 192 249 137 275 75 283 46 282 43 279 46 278 72 277

134 266 187 244 224 213 237 199

N NNE/ NE/ ENE/ E/ ESE/ SE/ SSE/ (Shade) NNW NW WNW W WSW SW SSW s HOR

Jan. 25 25 35 117 183 235 251 247 238 196 Feb. 29 29 72 157 213 244 246 224 207 234 Mar. 33 41 116 189 231 237 221 182 157 265 Apr. 36 84 151 205 228 216 178 124 94 278 May 40 115 172 211 219 195 144 83 58 280 June 51 125 178 211 213 184 128 68 49 278 July 41 114 170 208 215 190 140 ' 80 57 276 Aug. 38 83 149 199 220 207 172 120 91 272 Sep. 34 38 111 179 219 226 213 177 154 256 Oct. 30 30 71 151 204 236 238 217 202 229 Nov. 26 26 35 115 181 232 247 243 235 195 Dec. 24 24 24 99 172 227 248 251 246 179

32' N. Lat N NNE/ NE/ ENE/ E/ ESE/ SE/ SSE/

(Shade) NNW NW WNW W WSW SW SSW s HOR

N NNE/ NE/ ENE/ E/ ESE/ SE/ SSE/' (Shade) NNW NW WNW W WSW SW SSW S HOR

Jan. 22 22 24 90 166 219 247 252 252 155 Feb. 26 26 57 139 195 239 248 239 232 199 Mar. 30 33 99 176 223 238 232 206 192 23* Apr. 35 76 144 196 225 221 196 I56-' 135 262 May 38 107 168 204 220 204 165 lift 93 272 June 47 118 175 205 215 194 150 99 77 273 July 39 107 165 201 216 199 161 113 90 268 Aug. 36 75 138 190 •218 212 189 151 • 131 257 Sep. 31 31 95 167 210 228 223 200 187 230 Oct. 27 27 56 133 187 230 239 231 225 195 Nov. 22 22 24 87 163 215 243 248 248 154 Dec. 20 20 20 69 151 204 241 253 254 136

40" N.Lat N NNE/ NE/ ENE/ E/ ESE/ SE/ SSE/

(Shade) NNW NW WNW W WSW SW SSW S HOR Jan. 20 20 20 74 154 205 241 252 254 133 Feb. 24 24 50 129 186 234 246 244 241 180 Mar. 29 29 93 169 218 238 236 216 206 223 Apr. 34 71 140 190 224 223 203 170 154 252 May 37 102 165 202 220 208 175 133 113 265 June 48 113 172 205 216 199 161 116 95 267 July 38 102 163 198 216 203 170 129 109 262 Aug. 35 71 135 185 216 214 196 165 149 247 Sep. 30 30 87 160 203 227 226 209 200 215 Oct. 25 25 49 123 180 225 238 236 234 177 Nov. 20 20 20 73 151 201 237 248 250 132 Dec. 18 18 18 60 135 188 232 249 253 113

44° N. Lat N NNE/ NE/ ENE/ E/ ESE/ SE/ SSE/

(Shade) NNW NW WNW W w s w SW SSW s HOR Jan. 17 17 17 64 138 189 232 248 252 109 Feb. 22 22 43 117 178 227 246 248 247 160 Mar. 27 27 87 162 211 236 238 224 218 206 Apr. 33 66 136 185 221 224 210 183 171 240 May June

36 96 162 201 219 211 183 148 132 257 May June 47 108 169 205 215 203 171 132 115 261 July 37 96 159 198 215 206 179 144 128 254 Aug. 34 66 132 180 214 215 202 177 165 236 Sep. 28 28 80 152 198 226 227 216 211 199 Oct. 23 23 42 111 171 217 237 240 239 157 Nov. 18 18 18 64 135 186 227 244 248 109 Dec. 15 15 15 49 115 175 217 240 246 89

48° N.Lat N NNE/ NE/ ENE/ E/ ESE/ SE/ SSE/

(Shade) NNW NW WNW W WSW SW SSW s HOR Jan. 24 24 29 105 175 229 249 250 246 176 Jan. 15 15 -15 53 118 175 216 239 245 85 Feb. 27 27 65 149 205 242 248 232 221 217 Feb. 20 20 36 103 168 216 242 249 250 138 Mar. 32 37 107 183 227 237 227 195 176 252 Mar. 26 26 80 154 204 234 239 232 228 188. Apr. 36 80 146 200 227 219 187 141 115 271 Apr. 31 61 132 180 219 225 215 194 186 226 May 38 111 170 208 220 199 155 99 74 277 May 35 97 158 200 218 214 192 163 150 247 June 44 122 176 208 214 189 139 83 60 276 June 46 110 165 204 215 206 180 148 134 252 July 40 111 167 204 215 194 150 96 72 273 July 37 96 156 196 214 209 187 158

188 146 244

Aug. 37 79 141 195 219 210 181 136 111 265 Aug. 33 61 128 174 211 216 208 158 188 180 223

Sep. 33 35 103 173 215 227 218 189 171 244 Sep. 27 27 72 144 191 223 228 223 220 182 Ocl. 28 28 63 143 195 234 239 225 215 213 Oct. 21 21 35 96 161 207 233 241 242 136 Nov. 24 24 29 103 173 225 245 246 243 175 Nov. 15 15 15 52 115 172 212 234 240 85 Dec. 22 22 22 84 162 218 246 252 252 158 Dec. 13 13 13 36 91 156 195 225 233 65

Reprinted with permission from the 1989 ASHRAE Handbook—Fundamentals.

Table 3.5 -Maximum solar heat gain factor (SHGF)



3.1.3.4 External shading effect

The values for the SHGF shown in Table[3.5] are for direct solar radiation -When the suns shine on the glass. External shading from building projections may shade all or part of the glass. In these cases, only an indirect radiation reaches the glass from the sky and ground.[8]

3.1.3.5 Design conditions

The cooling load calculations are usually based on inside and outdoor design conditions of the temperature and humidity. The inside conditions are those that provide satisfactory comfort. Table 3.6 lists some suggested values. [8]

Air Temperature (DB) F

Relative Humidity (RH) %

Maximum Air Velocity (FPM)

Clothing Insulation (Clo)

Winter 68-72 25-30 30 0.9

Summer 76-78 50-55 50 0.5

Table 3.6- Recommended indoor air design conditions for human comfort

3.1.3.6 Lighting

The equations for determining cooling load due to heat from lighting is

Q=3.4 *W*BF*CLF (3-6)

Where,

Q=CooIing load from lighting, BTU/hr

W= Lighting capacity, Watts

BF=ballast factor

CLF=Cooling load factor for lighting

The term W is the rated capacity of the lights in use, expressed in watts, in many applications, all of the lighting is on at all times, but if it is not, the actual amount should be used. The value 3.4 converts watts to BTU/hr.



The factor BF accounts for heat losses in the ballast in Fluorescent lamps, or other special losses, A typical value of BF is 1.25 for fluorescent lighting. For incandescent lighting, there is no extra loss, and BF =1.0

The factor CLF accounts for storage of part of the lighting heat gain effect. The storage effect depends on how long the lights in cooling system are operating, as well as the building construction, type of lighting fixtures and ventilation rate.

3.1.3.7 People

The heat gain from people is composed of two parts. Sensible heat and latent heat resulting from perspiration. Some of the sensible heat may be absorbed by the heat storage effect, but not the latent heat. The equations for cooling load from sensible and latent heat gains from people are [10]

Qs=q s *n*CLF. . . . (3 .7)

QL=q i* n • (3.8)

Where,

Qs, Ql= Sensible and latent heat gains (Loads)

qs, ql ^Sensible and latent heat gains per person.

n = number of people

CLF =Cooling load factor for people.

The rate of heat gain from people depends on their physical activity. The rates are suitable for a 75 F DB room temperature. Values vary slightly at other temperature, as noted.

The heat storage effect factor CLF applies to the sensible heat gain from people .If the air-conditioning system is shutdown at night. However no storage should be included, and CLF =1.0. Table 3.7 lists values of CLF for people.



Total Heat Adults Sensible Latent Adult Adjusted Heat, Heat,

Degree of Activity Male M/F a Btu/h Btu/h

Seated at theater Theater—matinee 390 330 225 105 Seated at theater, night Theater—night 390 350 245 105 Seated, very light work Offices, hotels,

apartments 450 400 245 155

Moderately active Offices, hotels, office work apartments 475 450 250 200

Standing, light work; Department store, walking retail store 550 450 250 200

Walking; standing Drug store, bank 550 500 250 250 Sedentary work Restaurantb 490 550 275 275

Light bench work Factory 800 750 275 475 Moderate dancing Dance hall 900 850 305 545 Walking 3 mph; light

machine work Factory 1000 1000 375 625

Bowling c Bowling alley 1500 1450 580 870 Heavy work Factory 1500 1450 580 870 Heavy machine

work; lifting Factory 1600 1600 635 965 Athletics Gymnasium 2000 1800 710 1090

Notes 1. Tabulated values are based on 75°F room dry-bulb temperature. For 80°F room dry-bulb, the total heat remains the same, but the

sensible heat values should be decreased by approximately 20%, and the latent heat values increased accordingly. " Adjusted heat gain is based on normal percentage of men, women, and children for the application listed, with the postulate that the

gain from an adult female is 85% of that for an adult male, and that the gain from a child is 75% of that for an adult male. b Adjusted total heat gain for Sedentary work. Restaurant, includes 60 Btu/h for food per individual (30 Btu/h sensible and 30 Btu/h latent.) ' Figure one person per alley actually bowling, and all others as sitting (400 Btu/h) or standing or walking slowly (550 Btu/h).

Reprinted with permission from the 1997 ASHRAE Handbook—Fundamentals.

Table 3.7 Rates of heat gain from occupants of conditioned spaces

3.1.3.8 Equipment and appliances.

The heat gain from equipment may sometimes be found directly from the manufacturer or the name plate data with allowance for intermittent use. Some equipment produces both sensible and latent heat.

3.1.3.9 Infiltration and ventilation losses

Infiltration of air through cracks around windows or doors results in both a sensible and latent heat gain to the rooms.



(a) Sensible heat loss effect of infiltration air

Infiltration occurs when outdoor air enters through building openings, due to wind pressure. The openings of most concern to us are cracks around window slashes door edges, open edges and open doors.

The amount of heat required to offset the sensible heat loss from infiltrating air can be determined from the sensible heat equations (3.9).

Qs=m *C *TC (3.9)

Where

Qs=Heat required to warn cold outdoor air to cold outdoor air to room temperature, BTU/hr.

m = Weight flow rate of outdoor air infiltration, lb/hr

TC = Temperature change between indoor and outdoor air, F

The weight flow rate of air (m) in equation (3.9) is expressed in lb/hr .However, air flow rates in HVAC work are usually measured in ft2/min (CFM) .If the units are converted, using the appropriate specific heat of air. The sensible heat equation is

QS=1.1 *CFM*TC (3.10)

Where,

Q s = Sensible heat loss from infiltration or ventilation air, BTU/hr

CFM= air infiltration (or Ventilation) flow rate, ftVmin.

TC 1 temperature change between indoor and outdoor air, F



(b) Latent heat loss effect of infiltration air

Since infiltration air is often less humid than the room air, the room air humidity may fall to an unacceptable level for comfort. If the room air humidity is to be maintained, water vapor must be added. The addition of this moisture requires heat (Latent heat) of vaporization of water) .This is expressed by the following equation[3.11]

QL=0.68*CFM (Wi '-W 0 ') (3.11)

Where,

Ql= Latent heat required for infiltration or Ventilation air, BTU/h

CFM = Air infiltration or ventilation rate, ft3/min

Wi', Wo' =higher (indoor) & lower (outdoor) humidity ratio is grains water/lb dry air (gr w/lb

<La)

To sum up, Equations are used to find the room air sensible and latent heat loss should always be calculated.

(c) Finding the infiltration rate

There are two methods used to estimate the CFM of infiltration air the crack method and the air change method.

(d) Air change method

This procedure for finding the infiltration rate is based on the number of air changes, per hour (ACH) in one room, caused by the infiltration.

CFM=ACH*V/60 ....(3.12)

Where,

CFM= Air infiltration rate to room, CFM

ACH =Number of air changes per hour for room

V= Room volume ft3


"i jWVEHSlTY 0M


3.1.4 The room cooling load

The room cooling load is the sum of each of the cooling load components (roof, walls, glass, solar, people, equipment and infiltration) in the room. When calculating cooling loads, prepared form is useful. A local calculation form is shown in table 5.11

3.1.5 Room peak cooling load

The air conditioning system must be sized to handle peak loads. We must know how to find them. The external heat gain components vary in intensity with time of day and time of year because of changing solar radiation as the orientation of the sun changes and because of outdoor temperature changes. This results in a change in the total room cooling load.

Some times it is immediately apparent to inspecting the tables at what time the peak load occurs but often calculations are required at a few different times. Some general guidelines can be offered to simplify this task from the CLTD, SHGF and CLF tables.

3.1.6 Building peak cooling load

The building cooling load is the rate at which heat removed from all air- conditioned rooms in the building at the time the building cooling load is at its peak value.

If peak cooling loads for each room were added, the total would be greater than the peak cooling load required for the whole building, because these peaks do not occur at the same time. Therefore, the designer must also determined the time of year and the time of day at which the building cooling load is at a peak, and then calculate it.

3.1.7 Diversity

On some projects, the actual building peal load may be less than the calculated value because of load diversity factor. In some buildings, at the time of peak load, usage practice may be such that all of the people are not present and some of the lights and equipment are not operating. In this case, a diversity factor or usage factor is sometimes estimated and applied to the calculated building peak in order to reduce it.

3.1.8 Cooling load

After the building cooling load is determined, the cooling coil load is determined, the cooling load is found.

The cooling coil load is the rate at which heat must be removed by the air-conditioning equipment cooling coil.

The cooling coil load will be greater than the building load because there are heat gains to the air-conditioning system itself. These gains may include

(i) Ventilation (outside air)


10 0 o 4 8



(ii) Heat gains to ducts

(iii) Heat produced by the air conditioning system fans and pumps

(iv) Air leakage from ducts

3.1.9 Psychometric chart [7,8,9]

The properties of atmospheric air can be represented in table or graphical form .The graphical form is called the psychometric chart. It is universally used because it presents a great deal of information very simply and because it is helpful in studying air-conditioning processes.

I M P A C T O F I N T E R N A L & E X T E R N A L F A C T O R S IN B U I L D I N G E N E R G Y C O N S U M P T I O N IN S R I L A N K A

Fig 3.2 Psychometric Chart

H. Ruchira Daminda Perera Page 21 October 2 0 1 0


3.1.10 The RSHR or condition line

The RSHR Line is defined as the line drawn through the room conditions with the room sensible heat ratio slope RSCL/RTCL

A Scale for sensible heat ratio slopes is shown on most psychometric charts to make it easier to draw lines with this slope.

The importance of the RSHR line is that it is the line on which any satisfactory supply air condition must lie. The reason for this is that it has the slope representing the correct proportion of sensible and latent heat removal.

3.1.11 Determining supply air conditions

The rooms in a building gain heat from number of sources. The rate at which heat must be extracted from a room to offset these gains was given the name room total cooling load. (RTCL) ;It is composed of two parts .The room sensible cooling load(RSCL) and room Latent cooling load.(RTCL).

The heat extraction, or cooling effect, is provided by supplying air to the room at a temperature and humidity low enough to absorb the heat gains.

The relationships are expressed by the sensible and latent heat equations 3.13 &3.14.

RSCL =1.1 *CFMs * ( t R - t s ) ....(3.13)

RLCL=0.68*CFMS* (W R - W s ) ....(3.14)

Where

RSCL = Room Sensible cooling load, Btu/hr

RLCL = Room latent cooling load, BTU/hr

CFM s= CFM of supply air.

(t R — t s)= temperature of room and supply, F

(W R-Ws-) = humidity ratio of room and supply air, gr/lb d.a

Equations 3.1 3 & 3.14 are used to find the required conditions of the supply air to offset the sensible and latent loads for each room. It is usual practice to apply the RSCL equation 3.13 to determine the supply air humidity ratio W s '



S u p p l y Ait-

Rou t 11

Retu rn (rqomlair

Fig 3.3- Process of air-conditioning system

3.1.12 The complete psychometric analysis[5]

We are now prepared to determine all of the required supply air conditions and the cooling coil capacity for proper air conditioning of the space, based on the following known information.

1. Room sensible and latent heat gains

2. Outside and inside design conditions.

3. Ventilation (outside) air requirements.

4. Either CFM or DB temperature of the supply air. One of these is selected and the other is then determined from the sensible heat equations .However, both must be in a range that is considered satisfactory for "good practice"

Supply air temperature values are usually chosen so that the temperature difference between room and supply air is between room and supply air is between 15-30 F Factors such as the type, and location of air supply outlets will affect the temperature difference selected.

The supply air CFM must neither be too littlie nor too great, to prevent discomfort from stainless or drafts. Fortunately this is usually not a problem if the supply air temperature and ventilation air quantity are selected with in acceptable values.



3.2 Simulation

3.2.1 Simulation software-DEROB-LTH [3]

DEROB-LTH which is an acronym for Dynamic Energy Response of Buildings LTH is a MS Windows based flexible simulation tool using a RC-network for thermal model design. The program consists of 8 modules. Six of the modules are used to calculate values for temperatures, heating and cooling loads. The calculations are performed in a dynamic way for each hour during a specified period of simulation. The calculations are influenced by climatic factors such as outdoor temperature, solar radiation and the sky temperature. Properties for the indoor climate of the building can be calculated based on these simulated results.

DEROB-LTH can simulate buildings of arbitrary geometries. The building elements can be described by one to five available shapes and the geometrical model of the building is assumed to be placed in a positive oriented Cartesian building coordinate system.

DEROB-LTH was originally developed at the Numerical Simulation Laboratory of the School of Architecture of the University of Texas at Austin. The DEROB-LTH modules are further developed to suit the local needs at the Department of Building Science at Lund Institute of Technology.

3.2.1.1 Energy transmission

Walls are built up of different materials with different thickness and thermal properties. DEROB-LTH divides the walls into a suitable number of layers and assigns internal nodes to the wall. A maximum of 7 nodes can be assigned inside each wall. A thermal property for the walls is assigned by input or by a material library. The inner and outer surfaces of the wall are each assigned one thermal node.

The window model uses one node for each pane and treats the nonlinear heat transfer between the panes in a detailed way using the first principles of physics. The absorption of solar radiation in each pane is also calculated with incident angle and all reflections between panes taken into account.

Outer surfaces are coupled to other thermal nodes as follows: - by conduction to the outermost of inner nodes in the wall - by long-wave radiation to the sky, ground and shading screens.

- by convection to the outdoor air



Space nodes are coupled to other thermal nodes as follows: - by air exchange, infiltration and forced ventilation, with

the outdoor air and adjacent volumes. - by advection connection between volumes - by convection to inner surfaces enclosing a volume In the heat balance

equations, loads from free heat and auxiliary equipments are taken into account.

3.2.1.2 Solar radiation

DEROB-LTH calculates solar loads for each surface in the model based on direct and diffuse solar radiation stored in a climate data file. Read more about the climate data file in the paragraph the climate data file.

Direct solar radiation reflected from a surface is treated as a source of diffuse radiation. Diffuse solar radiation transmitted through a transparent building element is treated as a source of diffuse radiation. Diffuse and direct solar radiation can be transmitted into adjacent volumes through transparent building elements.

3.2.1.3 Heating and cooling

DEROB-LTH supports heating and cooling according to two different types of schedules. Equipments can be sized or not. Internal heat loads include people, lighting and appliances according to two different types of schedules.

3.2.1.4 Ventilation

Air exchange between volumes can be modeled in three ways:

1. Air flow caused by advection connections between volumes is dependent on the openings between two volumes, temperature differences and static pressure. 2. Infiltration between a volume and the outdoor air can be specified according to two different types of schedules.


Inner surfaces are coupled to other thermal nodes as follows: - by conduction to the innermost of the inner nodes in the wall - by long-wave radiation to the inner surfaces in a volume - by convection to the indoor air

In the heat balance equations, loads from direct, diffuse and ground reflected solar radiation transmitted through windows are taken into account.

IMPACT OF INTERNAL * EXTERNAL FACTORS IN BUILDING ENERGY CONSUMPTION IN SRILANKA

3.2.1.5 S i m u l a t i o n m e t h o d & t e c h n i q u e

The simulation was carried out utilizing two volumes with one common opening (window) as depicted in Fig 3.4 and Fig 3.5

The dimensions of the volume 1 were considered as 2mx2mx2m (length x width x height) while the dimensions of the volume 2 were 10m x 10m xlOm. The small window with the dimensions of 1m x lm (height x width) was opened to outdoor. The window was positioned at the mid point, where centering both volume 2 and volume 1.

Fig 3.4 - I n s ide view of s i m u l a t e d mode l s

The energy simulation program, "DEROB-LTH" was used in simulated model to identify impact of cooling load in volume with common opening of lm x Im.

The primary purpose of energy simulation Program is used to find peak cooling load for different material with different orientation. It helps to determine the peak impact of cooling load that is required to maintain inside design conditions for both Volume 1 and volume 2 during of maximum outside temperatures .Interior walls of the building maintain adiabatic conditions since heat transfer from volume 2 to 1 is negligible.

The peak impact of cooling load was calculated in two different states. One was found when opening area was 1 m 2 and other was found when no opening area for each type of materials.


3. Forced ventilation between the volumes and the outdoor air is specified by direction and flow. The same forced ventilation is used during the whole period of simulation.


E y e v i e w . A l i l -ii * . ~ 1 n . . i l M r -I . i l l t < • l r | i i i i m i • ,• N i i t M - A n i w ^ M O V C :CtH • A l T D W f l

Fig 3.5 - Simulated model appearance


Then real impacts of cooling load for several materials were calculated and summarized in following tables.


3.2.2 Simulation input data [IS]

3.2.2.1 Wall

No Building element Materials used

Properties No Building element Materials used Thickness

(mm) Conductivity

(W/mk) Overall coefficient

(W/m2k) Wall

1 Cement wall Cement plaster

10 1.2 5.45 1 Cement wall

Cement block

200 1.2

5.45 1 Cement wall

Cement plaster

10 1.2

5.45

2 One brick layer wall

Cement plaster

10 1.2 4.83 2 One brick layer wall

Brick 80 0.42

4.83 2 One brick layer wall

Cement plaster

10 1.2

4.83

3 Double brick layer wall

Cement Plaster

10 1.2 2.97 3 Double brick layer wall

Double brick 160 0.42

2.97 3 Double brick layer wall

Cement plaster

10 1.2

2.97

4 Adobe block Cement plaster

10 1.2 2.85 4 Adobe block

Adobe block 200 0.6

2.85 4 Adobe block

Cement plaster

10 1.21

2.85

5 Improved wall Cement plaster

10 1.2 0.28 5 Improved wall

Brick 80 0.42

0.28 5 Improved wall

Rig foam 80 0.026


Brick 80 0.42


Cement plaster

10 1.2

0.28

Table 3.8 - Input properties of wall

October 2010 H. Ruchira Daminda Perera Page 28


3.2.2.2 Timber

No Building element Materials used Properties

Thickness (mm)

Conductivity (W/mk)

Overall coefficient (W/m2k)

Door 1 Door 1 Timber 20 0.15 7.5 2 Softwood Softwood 20 0.14 7 3 Hard wood Hard wood 20 0.16 8 4 Wood fiber low

density Wood fiber board low

20 0.05 0.61

Air Space at 21 OC 20 0.024

Wood fiber board low

20 0.05

5 Wood fiber medium density

Wood fiber board medium

20 0.08 0.75

Air space at 21 0 C 20 0.024

Wood fiber board medium

20 0.08

6 Wood fiber high Wood fiber board high

20 0.13 0.88

density Air space at 21 0 C 20 0.024

Wood fiber board high

20 0.13

Table 3.9 - Input properties of doors


IMPACT OF INTERNAL & EXTERNAL FACTORS IN BUILDING ENERGY CONSIfMPTION IN SRILANKA

3.2.2.3 W i n d o w s

N o Bui lding element

Mater ia ls used

Propert ies Bui lding element

Mater ia ls used Thickn

ess (mm)

Transmiss ion

%

Reflectance 1%

Reflectance 2 %

Front

emitance %

Back

emitance %

W i n d o w types

1 Double Sol blue 20 18 30 84.5 66 glass Air 12mm

Kappakla 4 70 7 7 84.5 84.5 2 Tinted

glass Tinted glass 20 56 34 34

3 Trans glass

Trans glass 99 5 5 87 87

4 Plain glass

Plain

glass

88 8 87 87

T a b l e 3.10 - I n p u t p r o p e r t i e s of w i n d o w s

3.2.2.4 R o o f


IMPACT O F I N T E R N A L & E X T E R N A L F A C T O R S IN B U I L D I N G E N E R G Y C O N S U M P T I O N IN S R I L A N K A

Fig 3.6 View of roof in simulated building

No Type Building element

Materials used Properties No Type Building element

Materials used

Thickness (mm)

Conductivity (W/mk)

Overall coefficient (V77m2k)

Roof with ceiling

1 Roof 1 Roof Polyinsulation 25 0.036 1.34 1 Roof 1

Asbestos 6 0.22

1.34 1 Roof 1

Ceiling Asbestos 6 0.22

1.34

2 Roof with tile and timer ceiling

Roof Polyinsulation 25 0.036 1.20 2 Roof with tile and timer ceiling Asbestos 6 0.22

1.20 2 Roof with tile and timer ceiling

Tile 10 0.24

1.20 2 Roof with tile and timer ceiling

ceiling Timber 10 0.15

1.20

3 Roof asbestos roof Asbestos 6 0.22 18.33 3 Roof asbestos 18.33 3 Roof asbestos

Ceiling Asbestos 6 0.22

18.33

4 Roof with timber

Roof Asbestos 6 0.22 13.76 4 Roof with timber

13.76 Roof with timber

Ceiling Timber 10 0.15

13.76

Table 3.11-Input properties of roof with ceiling



3.2.2.5 Slab

No Building element

Materials used Properties

Thickness (mm)

Conductivity (W/mk)


Slab I Slab Cement plaster 10 1.2 12.02

Concrete 113 1.7

Cement plaster 10 1.2

Table 3.12 -Input properties of slab

lm x lm Floor

H Ruchira Daminda Perera

Fig 3.7 View of floor in simulated building

October 2010 Page 32


3.2.2.6 Floor

No Building element Materials used Properties No Building element Materials used Thickness (mm)

Conductivity (W/mk)


Floor 1 Floor Earth 500 1.4 2.48 1 Floor

Concrete 50 1.7 2.48 1 Floor

Cement plaster 20 1.2

2.48

2 Floor with tile Earth 500 1.4 2.47 2 Floor with burnt clay Concrete 50 1.7

2.47 2

Clay tiles 15 0.8

2.47

3 Floor with granite Earth 500 1.4 2.54 Concrete 50 1.7

2.54

Granite 20 3

2.54

4 Floor with limestone Earth 500 1.4 2.5

5 Floor with marble Concrete 50 1.7

2.5

Marble/ Limestone 20 1.5

2.5

Table 3.13- Input properties of floor

3.3 Simulation results

3.3.1 Peak cooling load of walls for different building orientations

Angle

Peak cooling load in Watts

Angle Adobe Block U=2.85

Double Brick Wall U=2.97

One Brick U=4.82

Improved Wall U=0.28

Cement Block U=5.45

0 4.4 6.9 12 0.3 7.9 45 8.6 12 19 0.5 14.6 90 15 20 36 0.9 25 135 15 20 36 0.9 25.5 180 12 17 29 0.7 21.6 225 14 22 40 0.8 25.7 270 14 21 40 0.7 25.3 315 8.3 13 24 0.5 15.2 360 4.4 6.8 12 0.3 7.9

Table 3.14 Peak cooling load in watts for different walls with different facing angle



3.3.2 Peak cooling load of timber (door) for different building orientations

Angle

Peak cooling load in watts

Angle Timber U=7.5

Soft wood U=7

Hard wood U=8

Wood fiber low density 0 0 . 6 1

Wood fiber medium density 0 0 . 7 5

Wood fiber high density U=0.88

0 19.1 18.6 19.6 5 6.9 8.8 45 30.6 30.1 31.3 7.3 10.5 13.2 90 62.8 62.3 63.9 14.5 21.1 27.2 135 59.5 59.2 61.1 14.2 20.5 26.2 180 41.1 39.9 42.3 10.1 14.3 18.9 225 66.6 65.7 68.3 16.1 21.2 29.6 270 69.4 67.8 71.1 16.6 23.5 30 315 40.3 39.2 41.3 9.9 13.8 17.4 360 19.1 18.6 16.6 4.8 6.9 8.8

Table 3.15- Peak cooling load in watts for different timber with different facing angle

3.3.3 Peak cooling load of windows (Glass) for different building orientations

Angle Peak cooling load in Watts

Angle Plain glass Double glass Heat reflective Tinted Void 0 46.1 0 0 0 0 45 129 13 67.2 41.11 35.2 90 193 52 111 64 72.7 135 142 22 75.9 44.3 42.4 180 48 0 2.1 0 0 225 144 15 79 46.7 46.1 270 188 40 111 66.3 74.3 315 131 7.7 72.2 43.2 39.6 360 46.1 0 0 0 0

Table 3.16- Peak cooling load in watts for different glasses with facing angle



3.3.4 Cooling load of roof for no of hours per day

Cooling load variation in Watts Cooling load variation in Watts Asbes Asbes

Asbestos tos Asbes Asbestos Asbestos tos Asbes Asbestos with roof tos with with roof tos with polyinsula with roof polyinsula polyinsula with roof polyinsula tion roof asbest with tion roof tion roof asbest with tion roof and OS timber and and OS timber and

Ho Timber ceilin ceilin asbestos Ho Timber ceilin ceilin asbestos ur ceiling g g ceiling. ur ceiling g g ceiling. 1 1.6 3.2 3 1.7 13 -2.9 -4.1 -4 -3 2 1.6 3.2 3.1 1.7 14 -3.5 -4.7 -4.6 -3.6 3 1.7 3.3 3.2 1.8 15 -3.5 -4.6 -4.5 -3.6 4 1.7 3.4 3.2 1.8 16 -3 -3.9 -3.9 -3 5 1.7 3.4 3.2 1.8 17 -1.6 -2.4 -2.4 -1.7 6 1.8 3.4 3.3 1.8 18 1.3 0.9 1 1.3 7 1.8 3.4 3.3 1.8 19 1.3 2.6 2.5 1.3

8 1.7 3.3 3.2 1.8 20 1.3 2.7 2.5 1.4 9 1.7 3.3 3.2 1.8 21 1.4 2.7 2.6 1.4

10 1.6 1.7 1.8 1.7 22 1.4 2.8 2.7 1.5 11 -0.1 -0.8 -0.7 -0.2 23 1.5 2.9 2.8 1.5 12 -1.9 -2.8 -2.8 -1.8 24 1.5 3.1 2.9 1.6

Table 3.17-cooling load in watts for different rooms



3.3.5 Cooling load of floor for no of hours per day

Ho ur

Cooling load in watts

Hour

Cooling load in watts

Ho ur Cement Floor

Granite floor

Tile floor

Marble floor Hour

Cement Floor

Granite floor

Tile floor

Marble floor

1 0.1 0.1 0 0.1 13 0.2 0.2 0.1 0.2 2 0.1 0.1 0 0.1 14 0.2 0.2 0.1 0.2 3 0.1 0.1 0 0.1 15 0.2 0.2 0.1 0.2 4 0.1 0.1 0 0.1 16 0.2 0.2 0.1 0.2 5 0.1 0.1 0 0.1 17 0.2 0.2 0.1 0.2 6 0.1 0.1 0 0.1 18 0.2 0.2 0.1 0.2 7 0.1 0.1 0 0.1 19 0.2 0.2 0.1 0.2 8 0.1 0.1 0 0.1 20 0.2 0.2 0.1 0.2 9 0.1 0.1 0 0.1 21 0.2 0.2 0.1 0.2 10 0.1 0.1 0 0.2 22 0.2 0.2 0.1 0.2 11 0.2 0.2 0 0.2 23 0.2 0.2 0.1 0.2 12 0.2 0.2 0 0.2 24 0.2 0.2 0.1 0.2

Table 3.18 -cooling load in watts for different floors

3.3.6 Cooling load in watts with respect to no of people

No of persons

Qs Sensible cooling load in watts

0 0 10 659.44 20 1318.87 30 1978.31 40 2637.75 50 3297.19 60 3956.62 70 4616.06 80 5275.5 90 5934.94

100 6594.37

Table 3.19- Cooling load in watts respect to area



Area in m2

Sensible cooling load in watts

0 0 10 0.31 20 0.62 30 0.93 40 1.24 50 1.55 60 1.86 70 2.17 80 2.48 90 2.79

100 3.1

T a b l e 3.20 —cooling load in w a t t s w i t h r e spec t t o a r e a

3.4 M a t h e m a t i c a l / G r a p h i c a l de r iva t i ve s

3 I M a t h e m a t i c a l d e r i v a t i v e s for d i f fe ren t wal l s

P e a k C o o l i n g L o a d R e q u i r e m e n t for dif ferent wal l s V A d o b * B l o c k

* - C « m » i » t B l o c k U-O.45

ftDiublt BRICK WALL U-2.97

T>- ON« BRICL U-4.82

< IMPROVED WALL

3 S O 1 O 0 1 5 3 2 0 O 2 S 0 l O O 3 S 0 4 0 3

ROTATION FROM SOUTH IN D»GR»«S

Fig 3.8 P e a k cool ing load for d i f ferent wal l s t h r o u g h s q u a r e m e t e r a r e a


3.3.7 C o o l i n g load in w a t t s w i t h r e spec t to a r e a


u A B 0.3 0.3 0.6 2.9 2.9 10

3 3 13 4.8 4.8 24

Table 3.21- A and B values with respect to U

R e g r e s s i o n line for A s n d B

V a l u e s o f U v /a lue in W ' m 2 K

Fig 3.9 - Linear regression for A and B for walls



(i) Error calculation

Direction e

Error in cooling load in Btu/h through per unit area (ft 2)

Direction e Cement block layer

Single layer brick wall

Double layer brick wall

Adobe layer

Improved double layer wall Correct

S 0 -0.63 1.29 1.31 0.53 1.68 0.84 E 90 3.82 7.93 4.9 3.31 1.76 4.34 N 180 3.72 6.65 4.61 3.06 1.8 3.97 W 270 3.92 9.3 5.34 2.99 1.69 4.65

o XL c i-o. a .

n 'j

u>

o o

U

Table 3.22 - Error in cooling load in BTU/h ft2 through square feet area.

i n

Error in cool ing load caluclation

f ( x ) - 4 . 6 9 x A 0.1

•Xirrent Block la^t U-0S6

Power Regression tor Douwe layer B U C K wan U-0 3J Adobe Layer U-0.5' r e s s o n for

Btocti layet 0 9 8

S n g e layer Brick v /a l Power Regression for U - 0 8 7 Adobe Layer U-0.S" Po war Regress on for • " r n p - o v e d Double layer S n g e layer Brick v /a l w a l U - 0 05

f(X) - 3.(13 X A 9 ^ ^ ^ | n y ^ y R r j , k MftM | m p s r R * f j r « s * i n n frr

wal ll-n n<,

f ( X ) = 5 X A ^ . 0 9

f{x\ - 0 x + 1.72

300

Rotat ion from S o u t h in d e g r e e s

Fig 3.10 -Error in peak cooling load in Btu/h per square feet area for walls



(ii) Error equations

material Q Error in Btu/h

Condition

Adobe block 5* (0) o u y O<0<36O

Double brick wall 3 .63*(0) 0 0 6 O<0 <360

One brick Wall 4.69*(0) 0 1 0< 0 <360

Improved wall 1.72 0< 0 <360

Cement block 3.5*(9) V 2 0< 0 <360

Table 3.23 Error in cooling load as mathematical expression

Direction Angle

Peak Cooling Load in Btu/h per (ft2)

Direction Angle One Brick U=0.87 Improved Wall U=0.05

Direction Angle 0.87 0.05 Direction Angle

Q Q Error Q Total Q Q Error Q Total

N 0 2.6 0.94 3.52 -1.5 1.72 0.19 S 90 3.5 7.36 10.8 -1.5 1.72 0.24 E 180 2.6 7.88 10.5 -1.5 1.72 0.19 W 270 3.5 8.21 11.7 -1.5 1.72 0.24

Table 3.24- Corrected cooling load comparison


(3.15)

(3.16)

(3.17)

(3.18)

(3.19)

(3.20)


Q = A + B * S m ( l l * ^ ) 0<e<180

Q = A - B * Sin(ll * ̂ ) j 80<9<360

A = 5 .02 *V- 1.78

B = U

Q E r r o r = 0 .19 * l n ( 6 ) -+ 3 . 3 5

Total Q = Q + Q Error

Where

Q =Heat load effect to cool ing load in wat ts

9 = Rotated angle of the bui lding from south

U =Overal l coefficient of heat t ransmiss ion in W / m 2 K


3.4.2 M a t h e m a t i c a l d e r i v a t i v e s for d i f fe ren t t i m b e r

Feak cool ing Lood Effect for different Timber 9 C D 0 - - -

C C D

0 5 0 I O C 150 2 0 0 2 5 0 0 0 3 5 5 0 4 0 0

r<n»«rte«l oiiijle fi o m s o u t h i n « l « < j i « *3

Fig 3.11 - P e a k cool ing load for d i f fe ren t t i m b e r m a t e r i a l t h r o u g h s q u a r e m e t e r a r e a

u A B 0.6 5 9.5 0.8 6.9 14 0.9 8.8 18 7 19 44 7.5 19 44 8 20 45

H Ruchira Daminda Perera

T a b l e 3 .25- A a n d B va lues w i t h r e spec t to U

October 2010 Page 42


Fig 3.12 Linear regression for A and B for timber

Q = A 4 B ~ S i n ( ^ e) O < 0 < 1 8 O ( 3 . 2 1 )

Q = A _ B . S i n ( ^ r 6 } 1 8 0 < © < 3 6 0 ( 3 . 2 2 )

A = 1 3 . 0 4 • ln(u) + 1 7 . 8 9 ( 3 . 2 3 )

B = 5 . 3 1 - In ( « ) + 8 . 4 6 ( 3 . 2 4 )

Q a C ^ Q equation"'" Qerror ( 3 . 2 5 )

Where

Q =Heat load effect to cooling Load in Watts

0 = Rotated angle of the building from south

U =Overall coefficient of heat transmission in W/ m K

Q act=Cooling load actual in watts

Q equanon=Cooling load from equations

Q error =Cooling load error in watts

H Ruchira Daminda Perera Page 4 3 October 2 0 1 0

IMPACT OF INTERNAL 4 EXTERNAL FACTORS IN BUILDING ENERGY CONSUMPTION IN SRILANKA

Angle

E r r o r peak cooling load in watts (Q error)

Angle Timber U -7 .5

Sof t wood U=7

Hard wood U=8

Wood fiber low density 11=0.61

Wood fiber medium density U = 0.75

Wood fiber high density U =0.88 Angle

7.5 7 8 0.61 0.75 0.88 0 •25.06 -24.66 -25.41 -6.44 -7.24 -7.42

45 -27.12 -25.46 -27.50 -8.27 -8.54 -8.53

90 -0.52 0.24 -0.61 -2.78 0.03 3.20

135 1.80 2.66 2.32 -1.37 1.46 4.48

180 -3.04 -3.34 -2.68 -1.34 0.17 2.69

225

mirror in upper value 270

mirror in upper value 315

mirror in upper value

360

mirror in upper value

T a b l e 3.26 E r r o r p e a k cool ing load in w a t t s

E r r o r i n c o o l i n g in w a t t s

10.00

0 20 40 60 80 100 120 140 160 180 200

A n g l e f r o m * n u i h i n d e g r e e s

Fig 3.13 E r r o r in p e a k cool ing load in w a t t s p e r s q u a r e feet a r e a for t i m b e r



U values Q error

U=7, U-7.5, U=8 = 17.56 Ln(X) -87.26

U=0.61,U=0.88, U=0.75 = X A2.97

Table 3.27 Error cooling load in watts with U values

3.4.3 Graphical derivatives for different glass

Fig 3.14- Peak cooling load for different glasses through per square meter area



Angle

GLF Value in B T U / h - f t 2

Angle Plain Glass Double Glass Heat reflective Tinted

0 14.6 0 0 0 45 40.8 4 21.3 13 90 61.2 16.3 35.1 20.3 135 44.9 6.85 24.1 14.1 180 15.2 0 0.67 0 225 45.6 4.66 25.1 14.8 270 59.6 12 7 35.1 21 315 41.7 2.44 22.9 13.7 560 14.6 0 0 0

T a b l e 3 .28- G L F v a l u e s for d i f fe ren t glass wi th d i f fe ren t facing a n g l e

DifT«>i « n t C 3 L F V a u e s In B l L i / T , f r 2

R o t a t i o n a n g l * f r o m S « M J T I - »

Fig 3 .15- G la s s load fac tor for d i f ferent glasses



3.4.4 G r a p h i c a l d e r i v a t i v e s for d i f fe ren t roofs

c o o l i n g L o a d v a r i a t i o n f o r c f f f e r e n r r o o f In w a r t s

5

1 o o

<m R o o f w l l h t i l * r « a t vwHh as-r-n*^-t o *

v R o o r w i i h T i m b e r - A ^ R O O f l

******** M o o f h o u r s p * r d a y

Fig 3.16 P e a k cool ing load v a r i a t i o n for d i f fe ren t roofs t h r o u g h s q u a r e feet a r e a

3.4.5 G r a p h i c a l d e r i v a t i v e s for d i f fe ren t floor

C o o l l n c i l o a d v a r i a t i o n t h r o u y h f l o o r

1

• f

~ C « n w -»t F l o o i O « . . r-*H« YIz> o r

^ T M f l o o r ^ Ivyl b l * * l o o r

H o u r s p e r d a v

Fig 3.17 - P e a k cool ing load v a r i a t i o n t h r o u g h d i f fe ren t floors p e r s q u a r e m e t e r a r e a



3.4.6 Graphical derivatives of people

A v e r a g e s e n s i b l e c o o l i n g l o a d h i W a t t s 7 0 0 0

M o o f P e r s o n s

Fig 3.18 Cooling load in watts with respect to number of people

3.4.7 Graphical derivatives of lights

S e n s i b l e c o o l i n g l o a d in w a t t s w i t h r e s p e c t t o A r e a

3 3

A r e a i n m 2

Fig 3.19 Cooling load in watts with respect to floor area in m



3.5 V a l i d a t i o n of s o f t w a r e

3.5.1 C a s e s t u d y 1 - R e s i d e n t i a l h o u s e

Calculate the room and building cooling loads for the residence shown in figure [3.20]

Fig 3 .20- S i m u l a t e d r e s iden t i a l h o u s e



3.5.2 Cooling load calculation- Theoretical approach

3.5.2.1 Residential cooling load.

The procedures described in Theoretical background section used for calculating cooling loads for commercial and industrial buildings. The procedures for determining cooling load for residencies are based on the same heat transfer principles. Homes are often conditioned 24 hours a day. These factors all lead to a simplification of load calculation. Only sensible loads are calculated, an allowance is made for latent loads. , and lighting loads are neglected. Approximations are used for people and infiltration loads. The procedure does not require determination of peak time of load or of heat storage effect, this being included in the data.

3.5.2.2 Cooling load from heat gain through structure

The cooling Loads from walls, roof, ceiling, and floors are calculated by use of the following equations[3.26]

Q=U *A*CLTD (3-26)

Where,

Q=Sensible cooling load, BTU/hr

U =Overall heat transfer coefficient, BTU/hr-fr^-F

A=Area of partions, wall or roof

CLTD =Cooling load temperature difference, F

The CLTD Values are listed in Table 3.29. The L (low), M (medium), and H (high) outdoor temperatures are listed in the footnotes to the table. These are found from Appendix B

The CLTD table is based on indoor temperatures of 75F. For other indoor temperatures, the CLTD should be corrected by 1 F for each 1 F temperate difference from 75F.

The CLTD values should also interpolated between the listed outdoor temperature differences from 75F.

The CLTD values should also be interpolated between listed outdoor temperature values .Colors of all exposed surfaces are assumed to dark.


IMPACT OF INTERNAL & EXTERNAL FACTORS IN BUILDING E N E R G Y C O N S U M P T I O N IN SRILANKA

Equation will be used. The CLTD will found from Table 3.2. Correcting it for the inside design temperature of 78 F. The outdoor temperature range falls in the M class.

Daily Range (F)

Denotes

0-16 L 16-25 M 25 > H

Table 3.29 -Outdoor range with difference class

Face direction

From Table

Inside Temperature(F)

Base Temperature(F)

CLTD(F)

North 13 78.8 75 9.2=13-(78.8-75)

South 16 78.8 75 12.2=16-(78.8-75)

West 23 78.8 75 19.2=23-(78.8-75)

East 23 78.8 75 19.2=23-(78.8-75)

Table 3.30-Calculated CLTD values

Calculation for CLTD

Values as Follows

CLTD = 13 - (78.8 - 75) = 9.2



3.5.2.3 Calculation for U values as follows

Building Structure

Layer No

Material Use Thickness(mm) U Values

(W/m2K)

Overall U

(W/m2K)

Overall U

(Btu/hft2 F)

Walls 1 Cement Plaster

10 1.2 2.02 0.36

2 Brick Work 200 0.42 3 Cement

Plaster 10 1.2

Slab 1 Cement Plaster

10 1.2 12.02 2.16

2 Concrete 113 1.7 3 Cement

Plaster 10 1.2

Floor 1 Earth 500 1.4 2.48 0.44 2 Concrete 50 1.7 3 Cement

Plaster 10 1.2

Door 1 Timber 20 0.15 7.5 1.35

Table 3.31 - Calculated values for different materials

Calculation for Q values as follows

South wall in Living Room

Q = UXAXCLTD

= 0.36X45.74X12.2

= 202.89

3.5.2.4. Cooling load from heat gain through windows

The sensible cooling load due to heat gains through glass (window and doors) is found by using glass load factors (GLF). These are listed in Table 3.32. The GLF Values account for both solar radiation, and conduction through glass. Values should be interpolated between listed outdoor temperatures.



Heat-Absorbing Clear Triple Regular Single Glass Regular Double Glass Double Glass Glass

Design Temperature, °F 85 90 95 100 105 110 85 90 95 100 105 110 85 90 95 100 105 110 85 90 95

No inside shading North 34 36 41 47 48 50 30 30 34 37 38 41 20 20 23 25 26 28 27 27 30 NE and NW 63 65 70 75 77 83 55 56 59 62 63 66 36 37 39 42 44 44 50 50 53 E and W 88 90 95 100 102 107 77 78 81 84 85 88 51 51 54 56 59 59 70 70 73 SE and SWb 79 81 86 91 92 98 69 70 73 76 77 80 45 46 49 51 54 54 62 63 65 South" 53 55 60 65 67 72 46 47 50 53 54 57 31 31 34 36 39 39 42 42 45 Horizontal skylight 156 156 161 166 167 171 137 138 140 143 144 147 90 91 93 95 96 98 124 125 127

Draperies, Venetian blinds, translucent roller shades fully drawn North 18 19 23 27 29 33 16 16 19 22 23 26 13 14 16 18 19 21 15 16 18 NE and NW 32 33 38 42 43 47 29 30 32 35 36 39 24 24 27 29 29 32 28 28 30 EandW 45 46 50 54 55 59 40 41 44 46 47 50 33 33 36 38 38 41 39 39 41 SE and SWb 40 41 46 49 51 55 36 37 39 42 43 46 29 30 32 34 35 37 35 36 38 South" 27 28 33 37 38 42 24 25 28 31 31 34 20 21 23 25 26 28 23 24 26 Horizontal skylight 78 79 83 86 87 90 71 71 74 76 77 79 58 59 61 63 63 65 69 69 71

Opaque roller shades fully drawn North 14 15 20 23 25 29 13 14 17 19 20 23 12 12 15 17 17 20 13 13 15 NE and NW 25 26 31 34 36 40 23 24 27 30 30 33 21 22 24 26 27 29 23 23 26 EandW 34 36 40 44 45 49 32 33 36 38 39 42 29 30 32 34 35 37 32 32 35 SE and SWb 31 32 36 40 42 46 29 30 33 35 36 39 26 27 29 31 32 34 29 29 31 South" 21 22 27 30 32 36 20 20 23 26 27 30 18 19 21 23 24 26 19 20 22 Horizontal skylight 60 61 64 68 69 72 57 57 60 62 63 65 52 52 55 57 57 59 56 57 59

"Glass load factors (GLFs) for single-family detached houses, duplexes, or multifamily, with both east and west exposed wails or only north and south exposed walls, Btu/h • ft 2. "Correct by +30% for latitude of 48° and by - 3 0 % for latitude of 32°. Use linear interpolation for latitude from 40 to 48° and from 40 to 32°. To obtain GLF for other combinations of glass and/or inside shading: GLF„ = (SC„/SC,)(GLF, - U,D,) + UaD„ where the subscripts a and / refer to the alternate and table values, respectively. SC, and U, are given in Table 5. D, = (/„ - 75), where ta = t0- (DR/2); ta is the outdoor design temperature and DR is the daily range. Reprinted with permission from the 1997 ASHRAE Handbook—Fundamentals.

Table 3.32 widow glass load factor

The glass sensible cooling load is determined from Equations

Q = A * GLF (3.27)

Where

Q= sensible cooling load due to heat gain through glass, BTU/hr

A =Axea of glass.ft2

GLF= Glass load factor, BTU/hr-ft2



3.5.2.5 People and appliances

The sensible heat gain per person is assumed to be an average 225 BTU/hr. If the number of occupants is not known in advance. It can be estimated as two times the number of bed rooms. Because the maximum load usually occurs in late afternoon .It is usual to assume that the occupants are in living and dinning areas for purpose of load distribution.

A sensible heat gain allowance of 1200-1^600 BTU/hr is typical for kitchen appliances. If the kitchen is to an adjacent room, 50% of this load should be assigned to that room. If large special appliances are used, their output should be individually evaluated.

3.5.2.6 Infiltration and ventilation

Infiltration rates are listed in table 3.33 in air changes per hour (ACH). Three categories of construction tightness are shown, described as follows:

AIR CHANGE RATES AS A FUNCTION OF OUTDOOR DESIGN TEMPERATURES

Outdoor Design Temperature, °F

Class 85 90 95 100 105 110

Tight 0.33 0.34 0.35 0.36 0.37 0.38 Medium 0.46 0.4X 0.50 0.52 0.54 0.56 Loose 0.68 0.70 0.72 0.74 0.76 0.78

Values for 7.5 mph w i n d am! indoor temperature of 75°F. Repr in ted wi th permiss ion from the 1997 ASHRAE Handbook—Fundamentals.

Table 3.33 Air change rates as a function of outdoor design temperature



V CFM = ACH * —

(3.28) 6 0 (3.28)

Where ,

C F M = Air infiltration rate into room, C F M

A C H = n u m b e r o f air changes per hour, (table 3.33)

V = room Volume , ft 3

The heat gain due to the infiltrating air is found from equat ion 3.29

Q = l . l * C F M * T C (3.29)

Where

Q=sensible cool ing load due to infiltrating air

C F M = F r o m Equat ion (3.28)

T C = Tempera ture change be tween inside and outdoor air.

If the infiltration air is expected to be less than 0.5 A C H , indoor air quali ty m a y be unsatisfactory .In this case, some ou tdoor air should be introduced through the air condi t ioning equipment , with its sensible heat contr ibut ion evaluated from equation 3.29


(i) Tight -Wel l fitted w i n d o w s and doors , wea ther str ipping, no fireplace.

(ii) Medium - A v e r a g e fit w i n d o w s and doors , fire place that can be c losed off.

(iii) Loose-Poorly fitted w i d o w s and doors , fire place wi thout shut -off.

The quanti ty of air infiltrating into the room is found from equat ion 3.28


Project: Residential house OutDB:87.8F In DB : 78.8 F D.R: 13.86 Location: Rathmalana OutWG:78.8F InRH=50% ACH :0.68

Room Name Living Room Dinning Room Bed Room 1 Plan Size 4x3= 12mM29.12FT ' 6.5x3= 19.5m^=209.82 FT" 4x3=12 m>129.12 FT"

Wall D U A CLTD BTU/hr D U A CLTD BTU/hr D U A CLTD BTU/hr S 0.36 45.74 3.86 64.2 S 0.4 77.472 3.86 108.73 S 0.4 56.17 3.86 163.1 w 0.36 130.7 9.14 434 E 0.4 209.82 9.14 697.3 W 0.4 116.2 9.14 386.19

W 0.4 80.7 9.14 268.19 Roof/ceiling 2.16 129.1 0 0 2.16 209.82 0 0 0.02 129.1 28.14 72.6687 Floor Partition Door S 1.4 28.75 3.86 150 S Windows D CLF D CLF D CLF

S 23.52 16 376 S 19.368 16 309.89 S 30.99 16 495.821 Infiltration 79.2 12.76 71.31 People 2x225 450 2X275 550 Appliances RSCL 1554 1946.9 1189.09



Room Name

Kitchen Bed Room 3 Bed Room 2

Plan Size 6X3=18m'=193.68 FT' 6.5x3= 19.5m'=209.82 FT' 6X3=18m'=193.68 FT'

Wall D U A CLTD BTU/hr D U A CLTD BTU/hr D U A CLTD BTU/hr N 0.4 142.8 6.14 319 S 0.4 67.788 3.86 95.14 N 0.4 135.6 6.14 302.67 E 0.4 96.84 9.14 322 E 0.4 188.84 9.14 627.57 E 0.4 87.16 9.14 289.65 W 0.4 96.84 9.14 322 W 0.4 44.116 9.14 146.61 W 0.4 87.16 9.14 289.65

Roof/ceiling 2.16 193.7 0 0 0.02 209.82 38.2 160.3 0.02 193.7 28.14 109.003 Floor Partition Door N 1.4 32.17 6.14 267 Windows D CLF D CLF D CLF Windows

N 29.7 16 475 S 19.37 16 309.89 N 38.74 16 619.776 Windows

w 28.41 16 454.5

Windows

Infiltration 119 115.88 106.97 People Appliances 1200 RSCL 3023 1909.9 1717.71 Building tota sum RSCL 11340.48 Duct gain 5 % 567.02 Duct leak 5 % 567.02 BSCL 12474.53 STCL=1.25 *BSCL 15593.16 Unit Size 1.3

Table 3.34 Residential cooling load form



3.5.4 Cooling load calculation- Simulated results approach

Simulation Results can be used to validate software application in here below shows Approximately Peak cooling load from Equations are equal to it from simulation.

3.5.4.1 Volume 1- Kitchen area

Building element

Wall area

(m2)

Window area

(m2 )

Door area

(m2 )

Cooling load through wall in Watts per area unit

Cooling load through Door in Watts per area unit

Cooling load through window in Watts per area unit

Peak cooling load in watts Direction e

wall 1 9 0 9.24 83.2 N 180 wall2 door 1.38 2.99 9.24 52.54 169.86 N 180 w2win 1.74 2.76 9.24 48 148.56 N 180 wall 10 9 0 9.19 82.75 W 270 wall 11 9 0 6.77 60.94 E 90 stslab H floor H

Total 545.31 infiltration 34.81 Appliances 351.6 Peak cooling load from equations 931.72 3187.42 W Peak cooling load from simulation 3023.06 W

Table 3.35 Peak cooling load from equation and simulation for -Kitchen



3.5.4.2 Volume 2 - Dinning area

Building element

Wall area (m2)

Window area (m2 )

Door area (m2 )




Peak cooling load in watts Direction 0

Wall 5 19.5 6.77 132.04 E 90 wall 6 7.2 1.8 8.36 44.16 139.69 S 0 wall 12 7.5 9.19 48 68.95 w 270 stslab H floor H

infiltration Appliances Peak cooling Load Peak cooling Load

From Equations From Simulation

3.74 161.15 505.57 1729.57 W

1946.87 W

Table 3.36 Peak cooling load from equation and simulation for -Dinning room

3.5.4.3 Volume 3 - living area

Building element

Wall area (m2)

Window area (m2 )

Door area (m2 )





Wall7door 1.86 2.64 8.36 44.16 132.14 S 0 wall 7win 2.34 2.16 8.36 46.1 119.14 S 0 wa!19 12 9.19 110.33 W 270 stslab H floor H

infdtration People Appliances Peak cooling load Peak cooling load

from equations from simulation

23.21 131.85

516.67 1767.52 W 1553.86 W

Table 3.37 Peak cooling load from equation and simulation for -Living area



3.5.4.4 Volume 4 - Bed room2

Building element

Wall area (m2)

Window area (m2 )

Door area (m2 )





Uwall 11 8.1 6.77 54.85 E 90 Uwall 10 8.1 9.19 74.47 W 270 Uwall 1 6.3 1.8 9.24 48 144.64 N 180 U wall 2 6.3 1.8 9.24 48 144.64 N 180 Roof H

Total 418.59 infdtration 31.34 Appliances Peak cooling load from equations 449.93 1539.23 W Peak cooling load from simulation 1717.71 W

Table 3.38 Peak cooling load from equation and simulation for Bed room 2



Building element

Wall Area (m2)

Window Area (m2 )

Door Area (m2 )




Peak cooling load in watts Direction 9

Uwall 5 17.6 6.77 118.84 E 90 Uwall 6 6.3 1.8 8.36 46.1 135.65 S 0 Uwall 12 4.11 2.64 9.19 187.9 533.84 w 270 Roof H

infdtration 33.95 Appliances Peak cooling load from equations 822.28 2813.03 W Peak cooling load from simulation 1909.89 W

Table 3.39 Peak cooling load from equation and simulation for Bed room 3

3.5.4.6 Volume 6 - Bed room 1

Cooling load through wall in

Cooling load through Door in

Cooling load through window in Peak

Wall Window Door Watts Watts Watts cooling Building Element

Area (m2)

Area (m2 )

Area (m2 )

per area unit

per area unit

per area unit

load in watts Direction e

Uwall 9 10.8 6.39 68.97 W 270 Uwall7door 1.41 2.64 8.36 46.1 133.49 S 0 Uwall7win 2.61 1.44 8.36 46.1 88.2 s 0 Roof H

290.66 infiltration 20.89 Appliances Peak cooling load from equations 311.56 1063.04B W Peak cooling load from simulation 1189.09 W

Table 3.40 Peak cooling load from equation and simulation for bed room


3.5.4.5. Volume 5 -Bed room 3


3.5.5 Comparison between simulated and calculated cooling loads

DEROB-Area Actual Area Peak cooling load(watts) -Theoretical

peak cooling load(watts)-Simulated

Volume 1 Kitchen area 3023.06 3187.42

Volume 2 Dinning area 1946.87 1729.57

Volume 3 Living area 1553.86 1767.52 Volume 4 Bed Room 2 1717.72 1539.23

Volume 5 Bed room 3 1909.89 2813.03

Volume 6 Bed room 1 1189.09 1909.89

Table 3.41 Comparison between simulated and calculated cooling loads


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IMPACT OF INTERNAL & EXTERNAL FACTORS IN BUILDING …