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re: heat loss through skylight
27 dec 2005
m ransley errs again:
>nick you are an idiot, there is to little sunshine in winter to give a
>net gain, the days are to short, the suns angle to low at chicago
>latitudes... you also assume its always sunny in chicago.
you are wrong on all counts. try numbers :-)
one more time: 460 btu/ft^2 of sun falls on the ground on an average 26.7 f
december day in chicago. unlike insulation, any skylight with more than 2
layers of glazing will gain more solar heat than it loses... 6 is optimal:
20 for n=1 to 8'layers of glazing
30 gain=460*.9^n-24*(65-26.7)/n'btu-ft^2-day
40 print 100+n;"'";gain
50 next
layers net gain
1 -505.2 btu/ft^2-day
2 -87
3 28.93997
4 72.00598
5 87.78537
6 91.26282
7 88.70224
8 83.11487
a skylight with a south tilt or a shutter or a reflector can gain more.
insulation can only lose heat.
nick
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