Our passive solar, straw-bale building
In 2003, with the help of many wonderful community volunteers, Willow Bend realized its dream of building an environmental education center! The center’s design incorporates passive solar features that allow the sun to warm up the colored, scored, and grouted concrete floors. The building has wood-frame construction with straw bale walls on the west, north, and east sides, and three trombe walls on the south. Trombe walls are 12-inch sand blocks filled with grout and mortared and painted black on the outside. The glass pane above the wall helps to trap heat, which is transferred to the interior of the building at night. Our ceilings feature blown-in insulation. The result is an eco-friendly, low-cost building that functions as both a comfortable workplace and useful education facility.
Willow Bend visitors often comment on the comfort of the building. During the day, we only use natural light and the natural heat of the sun. Only on rare occasions do we need supplemental heat from a small wood stove — usually fewer than six times during the winter. Because of its straw bale construction, our building is not as drafty, making 65º here actually feel warmer than in a conventional home. The building has a very organic and soothing feel, making it an ideal place to work, meet, and teach. Many other organizations in Flagstaff use our building for meeting and workshop space.
Here’s how our building compares to conventional construction:
| Walls | Willow Bend | R-33 |
|---|---|---|
| Conventional | R-12 | |
| Ceilings | Willow Bend | R-50 |
| Conventional | R-30 to R-38 | |
| Floors | Willow Bend | R-10 |
| Conventional | R-0 |

