Quote:
Originally Posted by Ryland
...if you don't insulate your underground walls then they act as a heat sink, a slow heat sink but still a heat sink, sitting next to a 50F degree wall will feel cold in the winter and you have the whole mass of the soil behind it pulling heat away from that wall, forever.
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Forever is not as long as you might think...
The biggest issue is water migration through soil. If you live in the right area, and choose your your building site correctly and take care to prevent occasional ground water migration, then the earth can act as a storage unit.
With this plan, it takes about 3 years for the surrounding ground to come up to temperature...
Heat flow through dry earth is about 16 feet per 6 months. If you house has a water migration free zone around it of 20 feet or better, it will draw heat from the house during the warmest months and return the heat to the house during the coldest months.
The concept is called
Passive Annual heat Storage (PAHS)
-AC