Would this work?

[Thyroyalgeek]

I know the title is kind of silly, but I would really love to have a little tropical space, (bigger than some tiny 8 × 6, like some people have, something more around the means of 20 × 15), and considering the fact that more mass holds heat, that would probably be more practical anyway. So I enjoy things like aroids, orchids, and bromeliads, (tropicals etc.) but that won't really work here where it gets 3° in the coldest of winters, so......... I am VERY determined to grow them. My desk is currently being taken up by plants, and I am getting a bit of an orchid enthusiast, wanting things like gongora, masdevallia, encyclia and such but can't because 90℅ humidity just really messes up a house. The idea is an underground greenhouse, basically, and it seems to be pretty efficient if well built, so how would an earth-bermed greenhouse, with several water barrels about 10' deep, with a cold sink work? Would it stay relatively even with temperature/humidity and little electrical heating? I really do want this to be able to work if I build it, I'm starting to get discouraged having people say, why don't you just grow "normal plants", like vegetables and regular flowers, just in the summer?