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