William McDonough + Partners envisions its house like a tree. The "bark" of the house is made up of thin, insulating films that would self-clean and self-heal if damaged. A curved roof with large eaves provides shade, which lowers the heat load in summer. The "trunk," or the frame of the home, consists of carbon tubes, while the "roots" are a heat-pump system buried in the yard.

Cook + Fox's house reacts to the weather, turning dark in the bright sun to insulate the house from heat and turning clear on dark days to absorb light and heat. The façade also captures rain and condensation to fill the household's water needs. Inside, walls and furniture are on rollers to take advantage of the fact that some spaces, such as bedrooms, are underutilized most of the day.

The Rios Clementi Hale Studios house has a garden façade that includes chickpeas, tomatoes and other plants. The plants also provide shade and cooling. A rooftop reservoir collects water and keeps the building cool, while rooftop windmills generate energy.

The Mouzon Design house uses tomorrow's technologies -- as well as ancient techniques to reduce energy use. Solar paneling built into the roof and façade provides electricity and hot water. The house also employs a "breeze chimney," an ancient architectural tool, as a kind of air conditioning.

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I have become a real fan of Steve Mouzon, as I become disillusioned with the idea that we can throw a lot of expensive heat pumps and photovoltaics on top of what we have always done and call it sustainable. He usually tries to use traditional techniques to capture wind and sun, but uses the Wall Street Journal exercise to go a bit overboard:

The top element of the Tower of Wind & Water is a wind generator that produces electricity. Nobody makes this exact shape of wind generator yet... many of the current generation of generators look as if they were engineered but not designed, leaving them inherently unlovable. This one, on the other hand, does its best to be beautiful while it is generating your electricity.