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Old 10-29-12, 01:55 PM   #16
AC_Hacker
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Quote:
Originally Posted by strider3700 View Post
how long can a passive house really go without sunshine?...
I have seen many studies on Passive Houses and heat coming in from the environment is one of may design criteria. There is also heat gain from living, even with 'green' appliances.

In areas where thermal input from the environment (usually solar) window location and size comes into play.

I have seen a study of a Passive House that was built in a particularly challenging micro-climate in Scotland (continual wind, no sun), where solar gain in the winter was insignificant, and window heat loss was substantially greater than their heat gain, so windows were minimized, and the highest performance windows were used. Wall insulation was maximized to balance internal heat gains.

Passive House designers use a very sophisticated spread sheet that includes all of these factors, and many, many more. The spreadsheet is called Passive House Planning Package (PHPP for short). You can buy it online, for $206, it is an incredible deal. The spreadsheet even considers the geometry of the house, since heat loss is directly related to surface area. So the package does not discourage high-surface area geometries, rather it calculates the other aspects (wall insulation being one) so that the house will meet Passive House criteria.

Best,

-AC
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