"There's not a stick of wood in the frame and roof of our home," says architect and homeowner Russell Johnson. His goal was to make the 1,900-square-foot design as energy efficient and spacious-feeling as possible. The result is a sort of freestanding contemporary cave: Most walls are thick, but the rear one is a thin glass membrane that opens elegantly to the garden.

The 12-inch-thick exterior walls are built with insulated concrete forms (ICFs) called Rastra, which are made of recycled Styrofoam mixed with cement. The walls have almost three times the insulating power of a wall framed with 2-by-4s; they are also termite- and fireproof and offer excellent sound insulation.

Tri-Tech Design
A wall of glass faces the landscape.

The living area, dining room, and kitchen are combined in one southwest-facing space. Steel posts and a steel beam make possible a 14- by 30-foot double-glazed window wall that brings afternoon light deep inside the home. Low-emissivity glass in this wall reduces solar gain and blocks ultraviolet rays. In cool months, the interior is warmed by a combination of passive solar energy (stored in the concrete floors and Rastra walls) and a hydronic radiant-heat system. Johnson says the energy bills for his house are lower than those for a neighboring home half the size.

DESIGN: Russell K. Johnson, Tri-Tech Design, Los Angeles (310/470-1948)

INFO: Rastra Corporation (www.rastra.com or 877/935-3545)