For the Waldorf School students in the Roaring Fork Valley of western Colorado, first through eight graders there are learning their reading, writing, and arithmetic (along with drama, drawing, and cultural studies) in the cozy confines of a solar-heated, naturally lit school built from bales of straw.
Straw-bale construction has been around for centuries. In Europe, one can find houses built out of straw that are over 200 years old. In the United States, the idea of building straw houses started in the late 1800s in the Nebraska Sandhills area, a region with no trees to use for lumber.
Besides being a waste product–it’s what’s left after grain is harvested — straw is a renewable resource, grown annually. It’s also extremely energy efficient. Testing indicates that a two-foot-thick bale has an insulation rating (R-value) that beats a standard wood frame wall insulated with R-19 batts by a factor of nearly three.
In the fall of 1996, the school board bought 13 acres in Garfield County, four miles east of Carbondale, Colorado. As the school considered what kind of building it wanted, a long list of requirements emerged: natural, energy-efficient, light, warm, alive, and earth. Passive solar straw-bale construction brought together all of these qualities. Building with straw also brought the added benefit of community involvement.
The building hosts five classrooms as well as administrative offices, bathrooms, and ample storage. Each classroom has south-facing windows for passive solar gain, and a light shelf and skylights for natural daylighting. Overhangs and an east-west building orientation prevent overheating and optimize solar gain. The school has hydronic radiant floor backup heat, and is plumbed for solar hot water collectors. The use of old growth wood was minimized by using Parallam posts, glue-lam beams, truss joists, and prefabricated trusses. The walls in between the classrooms have recycled cotton insulation for soundproofing. The ceiling is insulated with R-50 recycled fiberglass. The straw-bale walls also act as an excellent sound barrier.