A house for all seasons: a sensitivity to climate, site, and scarce resources makes this design ecologically inventive

Sunset, April, 1997 by Peter O. Whiteley

A sensitivity to climate, site, and scarce resources makes this design ecologically inventive

Some houses fool you. When you first look at the home designed and built by Berkeley architect Karl Wanaselja, you notice the industrial features - metal roof, two-story-tall windows, thick concrete walls, and large glue-laminated beams. They don't look particularly ecological. But it turns out that these manmade architectural elements are surprisingly essential to the house's earth-friendly character.

The glass walls on the ground floor accommodate warm weather by lifting up or rolling out of the way, blurring the line between living room and courtyard. House and garden intertwine - in come the perfumed scents of flowers, and out go owners Ian Nabeshima and Henry Kahle for a courtyard meal. In winter months, low-angle morning sunlight pours into the living room, where earth-tone concrete floors and massive concrete walls store its energy. Later in the day, the open doors provide cross-ventilation to disperse built-up heat.

The house also works with the site in rainy weather. Runoff from the metal roof enters a gutter, spirals down a 20-foot-long cluster of chains into a basin, and disappears into a 1,600-gallon cistern buried in the ground. The stored water is used to irrigate the garden during arid months.

Inside, a hydronic floor (warm water circulates through pipes in the concrete slab) and a heat-efficient Rumford fireplace warm the rooms. Even on the grayest of days, the 22-foot-tall insulated window walls provide ample daylight for the interior.

NOT JUST CONCRETE

Most poured-in-place walls have no "thermal break" to prevent the migration of heat and cold to or from interior living spaces. But these 15-inch-thick exterior walls contain a core of 3-inch-thick rigid insulation (expanded polystyrene). A heat-storing interior concrete wall separates the living-dining room from an adjacent bedroom. In winter months the walls facing the interior store and slowly radiate heat to the living spaces. Rigid insulation under the floor slab and around its edges prevents heat loss to the ground or outside air.

The house also exploits other virtues of reinforced concrete. It is fireproof and earthquake-resistant. The house's solid mass helps block sound - in this case, from a busy nearby freeway.

A CAREFUL WAY WITH WOOD

The architect took a sparing approach to construction materials. "The wood exposed in the ceiling was used up to four times as forms for the walls below," explains Wanaselja. The floor joists are made of salvaged cedar purchased at a wrecking yard. Some of the posts used in the interior and as part of a freestanding carport area were milled from trees that remained on the site after the cataclysmic Oakland fire of 1991.

Wanaselja selected exterior and marine-grade plywoods for the interior because the glue used in their manufacture does not outgas as much as that used in standard interior plywoods.

OTHER ECO FEATURES

* Galvanized metal roof that reflects sunlight to prevent heat buildup.

* Sprayed-in-place insulation (Nature Guard) made of recycled newspaper printed with soybean ink.

* Fire-resistant (type X), 5/8-inch plaster wallboard beneath all exposed wood siding.

* Solar panels for both hot water and radiant heated floor.

* Non- or low-toxic paint and natural wood finishes.

* Earth-pigmented paint and low-toxic (Mexe Seal) sealer on concrete floor.

* Drought-tolerant native landscape.