[tinkerbill]

Hey Piwoslaw,
There actually is a website and formula for using the earth in a big half-ball shape(insulated underneath the ball) then building new purpose-built eco-housing on top of it. I think the size of half-ball and how deep it went depended on location and size of house. As I recall, heat was dumped into the earth storage in the summer and heat was drawn back out in the winter. This pretty much made for an average temp all year round if engineered right. Perhaps I can take the time later to research my extensive bookmarks and come up with the website.
take care and stay warm/cold-average! Tinkerbill (new member from Yahoo wastewatts group)
PS: sorry I forgot to use the quote function. Newbie mistake.