Portland firm designs Passive House

The Passive House as envisioned by Root Design-Build.

U.S. attitudes toward building energy use have undergone a dramatic shift in recent years, but one Portland-based design-build firm says it thinks they need to go further. Root Design-Build plans to break ground on the 2,200-square foot Shift House in Hood River in September.

The company says it will meet the requirements of the Passivhaus Standard, which require energy use to be reduced by at least 90 percent over homes built to code. The home should cost only about 10 percent more than a standard one because the extra cost for high-efficiency materials will be offset by the fact that there will be no central HVAC system, says Root co-owner Milos Jovanovic.

Shift House will be built using commercially available building materials in new ways. The walls will have an R-value of 42 and the roof will have an R-value of 60, according to Root. For example, Jovanovic says he is going to use Structural Insulated Panels (SIPs) non-structurally by attaching them to standard framing. This means that nothing will span the entire width of the SIPs and there will be no thermal bridging in the structure, Jovanovic says.

Some of the materials used in the building—such as foam-based insulation in SIPs—will not be ideal from a sustainability point of view, Jovanovic admits. Insulation is the longest lasting and best system to invest money into, however, and there are no feasible alternatives available in the United States yet, he says. Because the house will have such a tight envelope, Root will pay very close attention to indoor air quality, he notes.

Operating costs of the Shift House will also be reduced because energy demand will be so low that an eight killowatt solar system should provide adequate electricity, allowing the home to effectively reach net-zero energy use, Jovanovic says.

Shift House is planned to be completed in spring 2010.