There's no other house like it on the Oglala Sioux's 2 million-acre Pine Ridge Reservation: Its walls are insulated by 18-inch strawbales rather than plastic sheeting, and its radiant-floor heating is much cheaper than the typical propane or electric. A frost-protected shallow foundation inhibits mold and is more energy-efficient than the damp basements common here.

Surrounded by South Dakota's open prairie, the rectangular home with its red-metal roof is one of four prototypes the local nonprofit Thunder Valley Community Development Corporation is building with South Dakota college students and the University of Colorado Boulder's Native American Sustainable Housing Initiative. Others will feature compressed-earth blocks, structural insulated panels made of plywood-faced foam, or standard wood framing.

Each is intended to help the planned 100-unit sustainable housing development meet all its energy needs on-site through rooftop solar panels, energy-storage batteries, and passive-solar design to take advantage of both sun and shade. The project won't erase the 4,000-unit housing crunch on the country's poorest reservation, but every bit counts in a place where dilapidated two-bedroom homes may shelter 15 or more people.

Thunder Valley is just one of many recent green-building efforts undertaken by tribes nationwide to attack housing shortages and offer alternatives to the standardized, often prefab "HUD homes" – that is, those built by the U.S. Department of Housing and Urban Development – common on reservations but often ill-suited to local climate and culture.