The author's company was chosen to build a community of small, zero-energy homes. The challenge was to keep them affordable, a goal that should be met over time owing to low fuel and maintenance costs.
Wedged-shaped battens made of pressure-treated lumber were fastened to the inside of the foundation forms 2 feet on-center. A double layer of 1 1/2-inch polyisocyanurate foam board is attached to the battens with screws and plastic washers.
Because of the 9 1/2-inch cavity created by the double 2x4 walls, the blown cellulose achieves an R-value of 31. The sides of the deep window wells are beveled 45 degrees to ensure that they let in plenty of light.