The natural extension (and perhaps the forbearer of) the green roof is the full sod house. More recognizable today as a Hobbit-hole (such as Bag-End in the Lord of the Rings), these homes can simply be stacked sod around a frame or dug into a hillside. The Hobbit-hole has all the benefits of a green roof, with some extended to the walls as well. They have excellent thermal efficiency year round, wonderfully limited runoff, and the added bonus of it being really freakin’ cool. Possible downsides may include a feeling of dampness, but if you have that in mind as you are building one of these dwellings of ultimate hippie/nerdy awesomeness, then you can take steps to minimize this. If you don’t live in the country or in a place with hills, not to worry! You can always build a hill to put your home in that will have all the envy-inducing attributes of one dug into the hillside. I want one, you want one, let’s all move to Hobbiton, y’all.