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Christ · 09-03-09, 12:04 AM

Looks like I'm in a 3-4 KwH/m2/Day area...

I found a few resources which say that a good average or starting point for new construction is to use the CF of the home and multiply by 4.5.

50x80x10=40000CF

40000x4.5 = 180kBTU.

This seems very high... I won't be losing as much heat as the normal house, due to the berm construction and living roof, as well as packed walls and cinder block/stone construction... I'll still use it for the estimate, though, since too much heat isn't an issue.

1 kWh/m2/day = 317.1 Btu/ft2/day, so 3kWh/m2/day = 951.3 BTU/ft2/day.

180k/951 = 189.275ft2 to produce enough heat to keep me going all day.

So this just raises more questions... how much thermal store do I need to keep going once the sun goes down?

Is this 200 ft2 of surface area, or area exposed directly to the sun? Is it area of heated piping?

I mean, if I put 200 feet of 1 ft2 piping coiled in a tank that only has 18 ft2 (3ftx6ft) of exposed surface for the sun to enter, but has 54 ft3 of interior space, will that work out correctly?

At least I have one part of this system figured out... I don't have to worry about it cooling the house at night, because it will technically keep heating as long as the temp of the house is lower than the temp of the liquid, and once the house gets hotter than the liquid, the siphon effect stops, because the heated area is lower than the house. Once the outside temp gets higher than the house again, the siphon effect picks up, starting to heat the house (or bypass loop) again.

09-03-09, 12:04 AM	#4
Christ Apprentice EcoRenovator Join Date: Aug 2009 Posts: 123 Thanks: 14 Thanked 1 Time in 1 Post	Looks like I'm in a 3-4 KwH/m2/Day area... I found a few resources which say that a good average or starting point for new construction is to use the CF of the home and multiply by 4.5. 50x80x10=40000CF 40000x4.5 = 180kBTU. This seems very high... I won't be losing as much heat as the normal house, due to the berm construction and living roof, as well as packed walls and cinder block/stone construction... I'll still use it for the estimate, though, since too much heat isn't an issue. 1 kWh/m2/day = 317.1 Btu/ft2/day, so 3kWh/m2/day = 951.3 BTU/ft2/day. 180k/951 = 189.275ft2 to produce enough heat to keep me going all day. So this just raises more questions... how much thermal store do I need to keep going once the sun goes down? Is this 200 ft2 of surface area, or area exposed directly to the sun? Is it area of heated piping? I mean, if I put 200 feet of 1 ft2 piping coiled in a tank that only has 18 ft2 (3ftx6ft) of exposed surface for the sun to enter, but has 54 ft3 of interior space, will that work out correctly? At least I have one part of this system figured out... I don't have to worry about it cooling the house at night, because it will technically keep heating as long as the temp of the house is lower than the temp of the liquid, and once the house gets hotter than the liquid, the siphon effect stops, because the heated area is lower than the house. Once the outside temp gets higher than the house again, the siphon effect picks up, starting to heat the house (or bypass loop) again. Last edited by Christ; 09-03-09 at 12:07 AM..