Mill Valley, California

Special award for earth-friendly design: Arkin Tilt Architects, Albany, CA (510/528-9830)

Challenge: For a family of five, design a house that’s as environmentally savvy as possible.

Solution: Every inch of this 1,944-square-foot, thick-walled straw-bale home demonstrates how to build for an age of limited resources. For starters, the architect removed only one tree ― a eucalyptus ― from the lot, then turned it into structural columns for the living room. Panels of pressed rye grass texture the ceiling, recycled glass appears in countertops, and salvaged Port Orford cedar beams are used as interior trim. Even the sliding panels along the main storage wall are old doors that have been rehung.

Special effects:
• The home feels larger than it is, thanks to a 16-foot-tall “great room” that runs almost its length and opens to a covered patio. The clerestory windows over this space brighten and vent the entire structure.

• Two features give the interior enough insulated mass to maintain a comfortable interior temperature year-round: thick walls covered with “stabilized earth” (a mixture of local soil and cement); and a radiant-heated floor made of concrete containing fly ash, an industrial waste by-product.

• Other environmentally friendly materials include fiber-cement siding, metal roofing, cabinets made of non-outgassing particleboard, low-VOC (volatile organic compound) finishes, and energy-efficient windows.