"Unlike conventional greenhouses, which are energy-intensive, Osentowski's system uses fans to drive warm air into the soil. Certain design elements, like a sauna, water tanks, insulation walls, a hot tub, and rock beds, are passive heating and cooling features that trap heat."
Cool story and I love the ideas presented. The above quote I have issues with since in just in the section above it was talking about it only taking the power of a couple light bulbs. Hot tubs are frikkin expensive and power intensive. I would assume saunas are too having to be hot enough to make steam especially in a cold environment.