Is This the Most Efficient Way to Build Homes in Terms of Energy?
In the late ’70s, Canadian engineer Harold Orr and his team embarked on designing an ultra-efficient home in Saskatchewan in response to a provincial conservation mandate during the oil embargo. They understood that the key was not finding greener ways to generate energy, but rather using less of it. Their goal was to create a superior thermos, not just a more affordable coffee maker.
According to MIT, the result was the 1978 Saskatchewan Conservation House, a cedar-clad trapezoid that cut energy usage by 85%—and helped inspire today’s globally recognized passive-house standard for building design. Adopted by thousands of buildings comprising tens of thousands of housing units, this concept marries vernacular building techniques, like orienting toward the sun, with cutting-edge insulation and air circulation systems. The formula for these efficient homes, standardized and shared by the German physicist Wolfgang Feist and the Swedish structural engineer Bo Adamson beginning in 1988, also bestows health benefits. With airtight exteriors and better air circulation, these homes offer improved interior air quality and significant noise reduction.
It’s a marriage of efficiency and rigorously applied physics, says Bronwyn Barry, a passive-house pioneer and principal of a Bay Area architecture firm. If homes are machines for living, passive-house design principles offer a blueprint for a better machine, highlighting just how poorly constructed postwar suburban sprawl can be.
Passive design focuses on the exterior, or envelope, which needs to be tightly insulated to avoid allowing heat out or unwanted heat in. This means using thick thermal insulation and high-quality, often triple-pane windows, which let in the sun’s light and warmth but keep heat from escaping. Heat loss (and, in warm weather, gain) through standard windows necessitates 25% to 30% of residential energy use. Construction also eliminates thermal bridges, or breaks in the envelope or insulation that allow heat to drain out. Think “boxy but beautiful,” as Barry once wrote: houses boast continuous layers of insulation while minimizing the cantilevers, corners, dormers, and other features that characterize the messy rooflines of McMansions. These design requirements result in airtight buildings, as measured by a blower door test: after a specially calibrated door-mounted fan sucks air out of the house to lower the air pressure inside, technicians look for gaps and cracks where higher-pressure air from the outside flows in.
