Design Strategies
- 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)
- FSC-certified wood trim and moulding
- Insulated WindowQuilt (www.windowquilt.com) shades
- Ridgeline, gable, and soffit vents keep attic area cool and dry
- Delta H20 Kinetic technology low-flow showerheads
- Caroma low-flush (1.6 gpm) toilets
