This duplex—the first of five that will serve as faculty housing at the Stevenson School in Pebble Beach, Calif.—in many ways was not a typical project for Turnbull Griffin Haesloop Architects. The San Francisco–based firm boasts a wealth of award-winning, high-performance designs, but this project required a new way of thinking.
A donation made construction of this limited-budget prototype possible, but it had to be certified by the Passive House Institute U.S. Sensitivity to old-growth Cyprus trees was also necessary, along with spaces that work for a variety of occupants.
Passive house principles dictate an extremely tight envelope, high R-values, and heat recovery systems. Pebble Beach is chilly and damp with perpetual winds, so impermeable walls, judicious glazing, and toasty interiors make sense. Passive House “teaches us ways houses lose energy that we normally wouldn’t think about,” explains firm principal Mary Griffin.
Griffin and project architect Jerome Christensen reached out to colleagues who had done passive projects to avoid trial and error, and enlisted Passive House consultant Prudence Ferreira. The pair’s due diligence paid off because they were informed from the start about places prone to leakage.
Paying particular attention to windows, doors, and fireplace flue was expected. Other trouble spots weren’t as obvious such as framing studs, thresholds, and exhaust systems. “We’ve never spent so much time thinking about a dryer vent,” Christensen jokes, “but you have to because that one vent basically sucks all of the warm fresh air out of the house.” The team had to find ways to make a tight house using traditional construction techniques and materials. The biggest difference is that the house’s exterior walls are double framed with an outer layer of 2x6 framing and an inner layer of 2x4s, which are positioned to minimize contact with the outer framing. That way there’s always insulation between the wood and the outside to break the thermal bridge usually created by studs. Recycled denim cellulose provides an outer layer of protection while mineral wool insulates the inside wall. Spray foam is even more effective but expensive, so it was used only for the roof. Highly efficient products like triple-pane windows, a sealed gas fireplace, and a recirculating oven vent took care of other trouble spots.
Windows are carefully positioned to capture coastal breezes and avoid excessive solar gain. The duplex program helped because a party wall between units allowed for more glazing on exterior elevations.
The house is a large, stately home to match other campus buildings. Grouping windows together in a double-height boxed bay helped create that look and meant fewer openings to seal. The bays also allow for abundant natural light from more than one direction. Although the windows are high-end, the lack of air conditioning countered that expense. This was the first Passive House project for the architects and their trusted builder, Avila Construction, but it passed the first blower door test, was completed on time, and didn’t surpass its budget. “It sounds like a lot,” Christensen says, “but it’s not that hard to do—it’s all just paying attention to details.”