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re: actual cost of intstalling geothermal
10 jul 2005
tony karp wrote:
>we're going to be getting some estimates for geothermal for our house...
you might also consider a sunspace or solar siding.
>northern virginia, just north of manassas, about 30 miles west of dc.
nrel says 1040 btu/ft^2 of sun falls a south wall on an average 30.6 f day
with a 40.1 daily max in stirling va, when a square foot of south glazing
might collect 0.9x1040 = 936 btu and lose 6h(80-35)1ft^2/r1 = 270, for a net
gain of 666 [evil] btu/day.
>last heating season, we used about 900 gallons of oil (it was colder than
>normal).
so you need about 900x100kbtu/5006dd = 18k btu/dd, eg (65-30.6)18k
= 618k btu on an average january day, which might come from 618k/666
= 929 ft^2 of transparent polycarbonate siding.
more house insulation and airtightness could help as well.
nick
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