PHILADELPHIA – After decades of near silence, a passive voice is making itself heard in American architecture.
So-called passive houses, which have been around in Europe but never really caught on in the United States, basically are built around the idea of making houses airtight, super-insulated and energy efficient.
The goal: The house creates almost as much energy as it consumes. Think of being able to keep your house warm without a traditional big furnace or cool with out an air conditioning unit.
“At this point there’s no reason why any developer can’t now build this way,” said Tim McDonald, whose firm has designed and built energy-efficient buildings with eco-friendly materials for more than a decade in Philadelphia, and recently entered the world of passive housing.
Signature features often include thick outside walls and roofs, highly-insulated windows and frames, and a south-facing orientation. The ventilation system pulls in fresh outdoor air and pumps out stale indoor air, but not before it’s used to heat or cool the incoming air to the same temperature.
Houses built this way can stay comfortable using 90 percent less energy than traditional construction homes, according to the Passive House Institute U.S., an Illinois-based certification, research and consulting group.
Though the idea was born in the United States, the roughly 20,000 internationally certified passive houses worldwide are in Europe – predominantly Germany, Austria and Scandinavia. Fewer than 100 exist here, but that’s changing from chilly New England to toasty Arizona to muggy Louisiana, said Katrin Klingenberg, Passive House Institute U.S. co-founder and executive director.
“People associate the passive house movement with Europe, but it comes out of the (American) oil embargo and energy crisis in the 1970s,” she said. “Then political change happened, (energy) prices came down ... but in Europe that didn’t happen, so they had reason to continue the research.”
Going passive isn’t solely the realm of new construction, either.
In McKeesport, Pa., outside Pittsburgh, a historic YMCA is being turned into a multiunit passive building to house people at risk for homelessness. In 2012 in New York City, Julie Torres Moskovitz’s firm, Fabrica 718, retrofitted a 110-year-old Brooklyn brownstone into the city’s first certified passive house.
“There’s a whole movement,” said Moskovitz, author of the new “The Greenest Home” (Princeton Architectural Press, 2013) on super-insulated and passive house design. “It’s a hotbed in Brooklyn of doing these retrofits.”
McDonald’s firm, Onion Flats, first tackled a three-home, low-income housing development completed in fall 2012 – Pennsylvania’s first to be certified under guidelines set by the Germany-based International Passive House Institute.
The stylish, 1,900-square-foot Bellfield Homes in North Philadelphia have a heating and cooling system one-eighth the size of what similar traditionally built homes require because they were built with an “airtight, super-insulated thermal envelope” that helps reduce energy use by 90 percent, McDonald said.
“Some passive houses are complex, but we took on the idea that we could do it ... with everyday construction,” he said.
Onion Flats’ next effort is The Stables development, with three of 27 luxury townhouses completed and passive house certification pending. Up next will be Ridge Flats, with shops and 130 apartments that McDonald’s firm wants to make the nation’s first passive-certified mixed-use project of its size.
Critics said passive houses work better in Europe because temperatures are relatively stable compared with many parts of the United States. They also cite some pricey materials, and predict it will be tough convincing Americans to part with their thermostats and let a home regulate its own temperature.
The Stables homes are selling for about $700,000. That’s for a 2,500-square-foot luxury town house with four bedrooms, three baths, garage, garden and energy-savvy bells and whistles such as solar panels, green roofs and airtight construction. McDonald said the price is comparable to nonpassive homes with similar amenities, in part because of cost savings from prefabricating the homes in modular sections and assembling them on-site.
“The way buildings have always been built is inefficient, so we’re tweaking the ways they’re built,” McDonald said. “If you do it the right way, it’s not more money.”