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