Sited for solar access, with the long axis of house oriented east-west
Passive solar floor plan with 10% south-facing glazing and 4 inches of thermal mass in the concrete floor, poured over 8 inches of XPS rigid-foam insulation (R-value of 40; local code is R-15)
Sized-for-latitude overhangs allow winter sun in for solar heating, but keep it out in the summer
Windows strategically placed to take advantage of natural ventilation
Windows minimized on east and west walls to avoid heat buildup from early- and late-day summer sun
Construction Details
2 x 6 stick-frame construction, spaced 24 inches on center, Forest Stewardship Council-certified wood
Walls insulated with polyurethane foam boards and spray foam within the walls; 1-inch-thick polyisocyanurate board serves as a thermal break between the outside of the studs and the siding for a total of R-40 (code is R-22)
Ceiling insulated with 12 inches of polyurethane board and polyurethane foam for a total of R-71 (code is R-38)
Standing-seam metal roof
Triple-pane, argon-gas-filled, fiberglass-frame windows. South-facing windows have SHGC of 0.63 and a U-value of 0.16
Mechanicals
No air-conditioning: Opening windows at night and closing them during the day is typically sufficient
Two Tamarach Technologies whole-house attic fans can flush out hot air when needed
Ceiling fans throughout aid cooling in summer
Panasonic WhisperGreen bathroom fans
High-efficiency energy recovery ventilator provides adequate exchange between indoor and outdoor air
Solar hot water system offsets about 68% of the electrical water heating
7.2 kW grid-tied PV system with battery backup provides 100% of electricity needs
Finishes & Products
PaperStone countertops made from recycled paper and nonpetroleum binders
Cabinets of FSC-certified wood and formaldehyde-free plywood
No-VOC paints, adhesives, and finishes used throughout
FSC-certified Oregon white oak flooring
Humabuilt (www.humabuilt.com) doors, made with wheat hull (interior) and wood veneer (exterior)
