There isn’t much tree cover at the site where the Department of the Interior built a 1,002-sq.-ft ranger cabin for the National Park Service’s Painted Hills unit, which presides over part of the John Day Fossil Beds National Monument in north central Oregon.

But the sun exposure in this spectacular and remote location is being played to advantage with a 5.6-kW photovoltaic system that, combined with a well insulated and relatively airtight shell, helped earn the gird-connected house a HERS Index rating of -46. (The targets were -15 with the PV system, +44 without.)

Designed by Jones and Jones Architecture of Seattle and Zero Energy Plans of Coupeville, Washington, the project also won a gold EnergyValue Housing Award last month at the International Builders’ Show in Orlando, Florida.

Mike Taylor, vice president of Kirby Nagelhout Construction, based in Bend, told the Daily Journal of Commerce that the large south-facing roof where the PV array is mounted is clearly the key energy driver. Moeover, the home’s insulation system and airtightness didn’t require special materials or construction techniques. “The exciting thing is that homes like this could be built without a lot of the exotic methods people associate with super-efficient residences,” he said.

Aiming for durability and comfort

The 1-bedroom, 1-bathroom house features what Nagelhout Construction vice president Chris Prahl, the project manager, says is a carefully constructed shallow foundation to accommodate the clay-laden soil at the site. The foundation is insulated to R-20 underneath and R-10 on the perimeter. The R-26 walls and the roof are structural insulated panels (SIPs), and the ceiling is insulated to R-43. Rim joist insulation is R-10 foam and R-22 fiberglass batts. All windows are triple-glazed.

In addition to the PV system, the building’s energy needs are served by a solar hot water system. The house equipped with both a heat recovery ventilation system and a high-efficiency minisplit heating and cooling system.

The building has Hardiepanel siding and metal roofing (expect for the garage roofing, which is PVC membrane roofing chosen to accommodate the 580-sq.-ft. patio that sits above the roof). A blower-door test showed an air-leakage rate of 198 cfm50.

Prahl says construction costs came in at $294,000, although he notes that the total includes the costs of building in an extremely remote location and, because it was a government project, wage rates that were higher than average for the area.