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...