Maybe you’ve heard of passive houses, the uber-insulated, German-inspired buildings that are drawing attention as the vanguard of deep-green construction methods.
The standard explanation is that they’re so well-sealed they can forego furnaces even in Northern climes, drawing enough warmth from body heat, windows and micro sources like hair dryers and tea kettles. That means they can use up to 90 percent less heating and cooling energy than standard homes built to code, according to proponents at thePassive House Institute-U.S.Naturally, the Europeans are way out ahead, boasting more than 25,000 passive-certified houses, condo blocks, office buildings and university structures – compared with a paltry 13 in the U.S.
The New York Times had a good explainer last fall of the environmental promise of the method (which also known as “passivhaus”). But most press coverage takes a, “Hey, isn’t this cute!” tone, suggesting that the few American passive projects have yet to become a full-fledged, financially compelling building trend.
I wanted to find out what the movement needs to really take off, so I talked to a builder and an architect in Seattle who have worked on some of the West Coast’s first passive projects. Both of them were deeply enthusiastic about the method’s potential for greening America’s building stock, and they were both aware that passive-house builders still face big challenges: They require friendlier zoning, new finance models and more experienced practitioners in the building trades.
If those barriers sound familiar to anyone working in green building trades, that’s because passive-house design isn’t much different than other energy-saving methods – it’s just more rigorous, according to Dan Whitmore, a 20-year builder trying to build Washington’s first certified passive building in Seattle’s Rainier Valley neighborhood.
“It’s not any new technology,” he said. “It’s not any new methods. It’s more attention to detail – laying a thick layer of insulation, air-sealing the building and using a real ventilation, not the ineffective elements we’ve been using for years.”
The two core requirements of the standard, created by the German physicist Wolfgang Feist in 1988, are stringent but admirably simple: A building must pass a blower-door test showing exceptional airtightness, and it must use no more than 15-kilowatt-hours of energy per square meter of floor area – that includes lights, water heating and all appliances. More details here.
To meet those limits, Whitmore’s using extra-thick 14-inch walls, plus extra ceiling insulation (he’s nicknamed the project “Foamhenge”). He’s working on an urban lot zoned for single-family housing, which includes a height-limit, an off-street parking requirement and a minimum setback from the street. The extra thickness of the walls can’t bring the house closer to the street or raise the roof height, so it cuts down on the interior space. On a small lot, those extra inches are crucial, Whitmore said, and a city that wants to promote energy efficient development should make zoning changes.
Since Whitmore plans to move into the house or rent it to a friend, he hasn’t faced the same financing challenges as Rob Harrison, principal at Harrison Architects and another passive proponent. Harrison’s met a bigger problem tied to the construction downturn.
“In 2009, half our projects went away because they couldn’t get financing,” he said. “Our clients need access to credit.”
He’s finishing plans for a passive cabin in rural Wauconda, WA, although he’d prefer to work on urban infill projects that increase the density of central cities. The energy savings of the vacation home will never make up for all the carbon burned getting to and from it, he said.
“Like any second home, it’s a case of doing something that’s less bad, but it’s not ultimately a sustainable path,” he said. “But we have to start somewhere, and these are people who are willing to experiment at this stage and have the wherewithal to do it.”
Harrison would like to see more cities offer property assessed clean energy programs and more utilities offer on-bill financing. Each method let’s homeowners pay back for their investments over time, helping them over the hurdle of prohibitive up-front costs.
If such options help grow the market for super-efficient homes, Harrison and Whitmore expects another issue to resolve itself: The scarcity of suppliers and contractors who understand the demands of passive construction.
Right now, few North American suppliers offer the top-of-the-line windows that passive building requires. While most North American windows are designed to prevent heat from leaking out, the passive standard requires panes that will still let thermal heat into a building, capturing the free warmth. That often requires paying for German-made windows and their shipping costs, Harrison said.
Whitmore found that Cascadia Windows of British Columbia offered the triple-pane, insulated-frame windows he wanted.
As the passive construction spreads, materials suppliers and ventilation-system workers may well find new opportunities in the market. Until then, Whitmore said he’s happy to do much of the learning himself.
“There was a learning curve, but it’s not steep,” he said. “It’s a fun challenge. Now that I’ve learned it, it’s great. I want to keep doing it.”