Passive Pride

When you’re old and frail, or maybe when your kids are old and frail, textbooks may refer back to the early 2000s as the time when we started applying the same rigorous science to the design of our built environment that for a hundred years already we had put to work in our cars, entertainment, and communication. Those future readers might wonder, “What took us so long?”

Nobody is doing more to advance building science today than the people behind Passive House. They advocate super-tight envelopes, extreme insulation and specialty windows, window placement that accounts for solar gain, and heat-exchanger ventilators and heat-recapturing appliances. They’re thoroughly mindful of thermal bridging—properly insulating I-beams from the outside, for example, since in the winter they suck heat out.

And one of the Passive House movement’s most significant achievements is analytical software that ties together all these techniques and materials and provides predictive power based on real analyses of houses built before.

Based on how you interpret data from the Association of Bay Area Governments, Passive House construction stands somewhere between 0.5 percent and 2.0 percent of total construction since the first Passive Houses were built in the Bay Area four years ago. But that number alone leaves the wrong impression. The designers, builders, and consultants behind those 30 projects have reimagined the way homes and other buildings can be constructed. They obsess over the numbers spat out by their modeling tools, not just because it’s so hard to meet the standards, but because the numbers mean real dollars that families don’t put into fossil fuels each month.

And the data keeps getting more granular. With proper construction, the body heat of an additional occupant or large pet can make a significant difference on the calculus. Luckily, with better data—painstakingly gathered after every job is complete—comes the ability to design a more reliably comfortable and efficient space.

Practitioners generally say that meeting Passive House standards boosts the cost of a new building by 10 percent and lowers energy cost by about 90 percent. Because more extreme climates require more energy, return on investment is quicker in less temperate places. Passive House software can tell builders and developers exactly how quick the ROI is.

More significantly, owners save on big-ticket maintenance since, as contractors will tell you, these buildings are built to last. Today’s average homebuilder may not be building for obsolescence but also isn’t building for longevity. Passive House standards, in contrast, generally keep up with the latest research on why structures tend to fail.

According to research led by Building Science Corporation founder Joe Lstiburek, buildings usually crumble from condensation in the walls due to air leakage through cracks and holes—not vapor diffusion through unmarred wall material.

Passive House puts energy conservation first. Graham Irwin, principal of Essential Habitat, a Bay Area design consultancy, can tell a client exactly what effects a personal preference has on efficiency, and software programs such as WUFI and PHPP help economize the process. The game has become all about the numbers.

“[Passive House] makes the science accessible and useful in the design and construction process in a way that it hadn’t been before,” says Irwin, whose portfolio of about a dozen Passive House-certified projects is arguably the largest in the area. “The general concepts were there, but it was light on execution—soft, nebulous. For example, yes, insulation is good, but is more always better? The answer is yes, but there are declining returns. It’s important to know where those diminishing returns are.” For example, 24 inches of insulation won’t do a homeowner much good if his or her windows are sub-par.

Windows play an important role in Passive House certification. Until recently, Passive Houses in the United States typically have used German-built windows because they were the only reliable systems available. But according to Prudence Ferreira, who founded Integral Impact in 2009, some of the window-makers’ installation manuals were written only in German, and the companies offered no customer support. Ferreira has been helping to convince American window companies to make products to their standards ever since.

Marvin Windows, she says, picked up the idea first, but they don’t offer a total solution. “We need to get manufacturers to step up,” Ferreira says, “because this is unsustainable.”

Awareness and knowledge of how to build to reach Passive House certification seems to be, as they say, trickling down, while the projects themselves are scaling up. Currently under construction in the Bay Area are three multifamily projects, which, in addition to requiring more energy than single-family homes and thus having more potential for energy savings, allow one well-sealed envelope to serve a number of occupants. According to Dan Johnson, who owns his own Bay Area consultancy, Design and Energy, one planner for a European-style apartment complex reportedly removed more than twenty furnaces from his building design, successfully replacing them with just one of similar size.

But one thing is for sure: research and development has been expensive. It has taken cash-flush owners and architects, including many from the Bay Area, to prove that Passive House can work in the United States. Now that many building professionals know what they’re doing, however, advocates are hoping that they can ignite an American efficiency revolution.

PHIUS (Passive House Institute US) and Passive House California are two groups pushing for the same thing who don’t always agree on how it should be done. One recent debate between the two organizations hinges on whether to relax the maximum energy-per-square-foot rule, specifically for heating. It’s a tough balance to strike. Johnson says a new generation is coming into leadership, and he tends to think this new crop of leaders is truly trying to unify things. “I guess it’s a testament to how powerful these ideas are that people would be so passionate about them to disagree,” he says.

“It’s kind of the difference between what refrigerator brand you pick,” Ferreira says. “No matter what certification you use, you’re still going to have a super-high-performance structure. It’s kind of like splitting hairs when you look at the bigger picture.” Ferreira, a PHIUS board member, says the organization does want to bridge the gap. After all, PHIUS held this year’s annual conference in San Francisco, the flagship city of Passive House California. “That’s one of the great things about these conferences,” she says. “It is definitely a living, breathing community, and we want it to be democratic.”

What’s the future of Passive House? It may be government-prompted or even mandated adoption. Some Passive House builders have been watching Europe and see writing on the wall; much of that continent may move to a passive standard for its minimum building code in the coming decades. Meanwhile, PHIUS has been pushing for partnerships with huge government programs like Energy Star, which has been wildly successful at increasing public awareness. According to Ferreira, the US Department of Energy is considering the Passive House standard for inclusion in its Net Zero Energy-Ready Home program, which may “become the next Energy Star.” Only time will tell, but the science is sound.

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Editor’s Note: An earlier version of this article misreported the year Integral Impact was founded. gb&d regrets the error.