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.

The phrase world’s greenest home isn’t entirely a boast. Green accreditation is conferred by the U.S. Green Building Council, a nonprofit that measures eight areas of sustainable building for its Leadership in Energy and Environmental Design ratings, including waste, water, energy, materials, and habitat. The Holland-Yates residence will easily exceed the top “LEED platinum” rating when it’s completed in November, and should earn the most LEED points of any home ever built. Its engineering was innovative enough to flummox San Mateo County officials, who initially wouldn’t approve a toilet system that fed into a front-yard meadow, and had to be persuaded that it wasn’t a health hazard.

All of this effort and expense—the couple says the finished complex will cost 2 to 5 percent more than “traditional homes,” which in their neighborhood start at about $5 million—is intended to serve a larger social purpose: to edify others and inspire them to build sustainable, regenerative houses. Holland and Yates plan to train docents to give tours of their home, and they want to create a Web site detailing the materials and vendors used for every aspect of its construction. They hope that, as with any “open source” project, others will carry on and improve what they’ve begun.