Passive solar design is the most economical way to provide heat for a home and also reduce cooling loads. But what do you do when passive solar design is impractical because your lot or the surrounding terrain makes it challenging or impossible? You make sure the home is very well insulated and install a very efficient heating and cooling systems. That’s what Henry Siegel, an architect from San Francisco based firm Siegel & Strain Architects, did for his family’s weekend home in Sonoma County. In order to preserve a meadow and take advantage of the panoramic views he located his home on a north facing hillside on his 2 1/2 acre lot. The site for the house didn’t have very good solar resources, so he couldn’t take advantage of efficient passive solar design. As Seigel says in Dwell Magazine, “Once you eliminate passive solar on this site, then the most important thing—because air-conditioning is more expensive and more damaging to the environment than heating—is heat avoidance.”
One way to get amazing insulation in a sustainable way is to construct a straw bale house, which also has the advantage of reducing wood for framing. Straw bale construction is incredibly efficient, both in terms of the quality of insulation it can provide as well as that it uses up a byproduct from the agricultural industry. Straw is the leftover stalks after the grain has been taken, and would otherwise be burned on the field and tilled back into the ground. For straw bale homes, the straw is baled and then used as the walls, which are then coated with plaster or adobe for a strong, healthy, fire and pest resistant building system.
Siegel and his family wanted a quiet home outside of the city where they could relax and get away from all the business. The home itself is a modest 1,200 square foot home with a breeze way in the center to help cool the house with natural ventilation. Heating in the winter comes from the radiant floors heated using the same water heater that heats the rest of the water for showers and sinks. The floors are concrete mixed with fly ash that help hold heat in the winter and keep the home cool in the summer. Windows are double paned and combined with the two foot thick R-40 straw bale walls keep the home nice and insulated, whether its 100 degrees outside in the summer or 40 in the winter. Other eco friendly touches include recycled glass and concrete counter tops as well as energy efficient appliances.
The home itself is simple, long and inspired by farm buildings with their long and linear construction. The roof line is also incredibly straight forward – a simple gabled roof with one dormer in front. Compared to many of the mansions and villas in the wine country area, this straw bale residence is simple and fits within the context of its surrounding. The gray exterior fits in with its surroundings and has a warm organic texture. And one of the key benefits of straw bale construction: friends and family helped build it. After house was framed, a group came over and cut and placed 90% of the straw bales in one day. Siegel describes it as “the modern-day experience of a barn raising.”
photos by JD Peterson