Sources: U.S. Green Building Council; Design Avenues LLC; Paul Holland and Linda Yates; Bloomberg

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Paul Holland and Linda Yates thought it only natural, when they set out to build a luxury home six years ago, that theirs would be the world’s greenest. In Silicon Valley—where Holland works as a venture capitalist and Yates as a management consultant—even competition is environmentally conscious.

The couple’s 5,600-square-foot home will be outfitted with a host of aggressively eco-friendly technologies and materials: a recycled-steel roof that diverts rainwater to a 50,000-gallon underground cistern; reclaimed stone left over from the construction of Chicago skyscrapers; solar panels powerful enough to provide electricity to the home, charge five electric cars, and still return energy to the grid; a cedar interior cut from sustainable forests (where trees are selectively harvested to minimize environmental damage); doors and windows of Portuguese eucalyptus approved by the Forest Stewardship Council; oak floors salvaged from old granaries; recycled-glass sinks; a recycled-steel kitchen hood.

The house has no paint, ducts, or HVAC, and it uses no fossil fuels. Sliding glass walls let in the breeze during the summer, and in the winter the home’s ground-source heat-exchange system pumps water deep underground to be warmed by the Earth’s thermal energy, then pushes it up to heat the floorboards. The home’s climate, lighting, and irrigation will be controlled remotely—by iPad, of course.