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Worked calculations for thermal loss example

This page shows the workings associated with calculations of heat loss from a semi-detached house as described on the example page. This example used the imperial quantities of BTU/hr, sq. ft., and °F.

Most of the calculations are fairly straight forward as most of the rooms are of regular shape, the only exception being the hall which extends up the stair well and onto the landing.

Workings of air change losses are at the bottom of this page.

  area
sq. ft
inside
temp
outside temp Temp diff U-value Loss in BTU
Dining Room            
back wall 72 70 30 40 0.18 518
window 40 70 30 40 0.51 816
party wall 136 70 65 5 0.38 258
ceiling 238 70 65 5 0.29 345
floor 238 70 30 40 0.12 1142
Lounge wall 112 70 70 0 0.39 0
Kitchen wall 112 70 65 5 0.39 218
Hall wall 24 70 60 10 0.39 94
             
Lounge            
front wall 72 70 30 40 0.18 518
window 40 70 30 40 0.51 816
party wall 120 70 65 5 0.38 228
ceiling 210 70 65 5 0.29 305
floor 210 70 30 40 0.12 1008
Dining wall 112 70 70 0 0.39 0
Hall wall 120 70 60 10 0.39 468
             
Kitchen            
back wall 32 65 30 35 0.18 202
window 16 65 30 35 0.51 286
side wall 95.75 65 30 35 0.18 603
back door 16.25 65 30 35 0.42 239
ceiling 84 65 72 -7 0.25 -147
floor 84 65 30 35 0.12 353
Dinning wall 112 65 70 -5 0.39 -218
Hall wall 48 65 60 5 0.39 94
             
Hall            
side wall 231.5 60 30 30 0.18 1250
window 16 60 30 30 0.51 245
front wall 28.5 60 30 30 0.18 154
front door 19.5 60 30 30 0.42 246
ceiling to roof 80 60 30 30 0.05 120
ceiling to bd 3 48 60 65 -5 0.25 -60
floor 108 60 30 30 0.12 389
Lounge/dr wall 144 60 70 -10 0.39 -562
Kitchen wall 48 60 70 -10 0.39 -187
Bedroom walls 48 60 65 -5 0.39 -94
             
Bedroom 1            
back wall 72 65 30 35 0.18 454
window 40 65 30 35 0.51 714
party wall 120 65 60 5 0.38 228
ceiling 238 65 30 35 0.05 417
floor 238 65 70 -5 0.29 -345
Bedroom 2 wall 112 65 65 0 0.39 0
Bathroom wall 112 65 72 -7 0.39 -306
Hall wall 24 65 65 0 0.39 0
             
Bedroom 2            
front wall 72 65 30 35 0.18 454
window 40 65 30 35 0.51 714
party wall 120 65 60 5 0.38 228
ceiling 210 65 30 35 0.05 368
floor 210 65 70 -5 0.29 -305
Bedroom 1 wall 112 65 65 0 0.39 0
Bedroom 3 wall 64 65 65 0 0.39 0
Hall wall 56 65 60 5 0.39 109
             
Bedroom 3            
side wall 64 65 30 35 0.18 403
front wall 32 65 30 35 0.18 202
window 16 65 30 35 0.51 286
ceiling 48 65 30 35 0.05 84
floor 48 65 60 5 -0.25 -60
Bedroom 2 wall 64 65 65 0 0.39 0
Hall wall 48 65 60 5 0.39 94
             
Bathroom            
back wall 32 72 30 42 0.18 242
side wall 112 72 30 42 0.18 847
window 16 72 30 42 0.51 343
ceiling 84 72 30 42 0.05 176
floor 84 72 65 7 0.25 147
Bedroom 1 wall 112 72 65 7 0.39 306
Hall 48 72 65 7 0.39 131
             
Air Change volume       rate  
Dining Room 1904 70 30 40 2 3046
Lounge 1680 70 30 40 1 1344
Kitchen 672 65 30 35 2 941
Hall 240 60 30 30 1.5 216
Bedroom 1 130 65 30 35 0.5 46
Bedroom 2 864 65 30 35 0.5 302
Bedroom 3 256 65 30 35 0.5 90
Bathroom 896 72 30 42 2 1505