It’s another sunny day on the Internet. Dozens of participants are lined up in their digital boxes attending Reimagine Buildings ’24, an online conference held in the spring dedicated, mostly, to Passive House, a quickly-growing approach to building that sharply reduces energy use by going simple: employing techniques like continuous insulation, air-tight sealing, and top quality windows; making better use of both sun and shade, and bringing in fresh air through advanced filtering.
Launched with a single house in Darmstadt, Germany, in 1991, Passive House has grown, says the International Passive House institute (founded in Darmstadt in 1996 and credited with developing the concept and overseeing its international standards), more than eightfold since 2010. Phius (Passive House Institute US), which produces its own standards (unlike those of their German counterpart, they are specific to different climates) in the US, notes that its rate of annual registrations has grown sixfold since 2018.
“Our growth in the last few years looks like the blade of a hockey stick,” said Katrin Klingenberg, director of Phius. Reimagine Buildings ’24, by the way, hosted about 700 participants, according to its organizers.
The reasons for this sharp progression include increased awareness, growing concern about climate change and indoor air quality, improved (and cheaper) technology, embrace from the construction community, and more help from government agencies.
A lot, of course, comes down to energy savings. A Passive House project, said Klingenberg, uses between 50 to 80% less energy than a typical building, depending on variables like size and location. That can add up to a lot of money. These reductions are a result of Passive House certification groups’ strict energy use demands. “You have to go through the process to design a building in a way you reach that high efficiency level,” summed up Jessica Grove-Smith, joint managing director at the Passive House Institute. “We realize there are a lot of ways to get there.”
The movement has also ballooned thanks to its employment in ever larger buildings. “We should kick the term Passive House to the curb,” said Klingenberg, who thinks that including the term “house” in Passive House is confusing. Her organization now uses the term “Passive Building” in its standards. Germany’s Passive House Institute’s database showcases apartments, offices, schools, even hospitals, cafeterias, swimming pools, and supermarkets. These can be market rate or affordable. Low rises or skyscrapers.
Reimagine Buildings ’24’s master of ceremonies was Michael Ingui, a New York architect who is founder of the Passive House Accelerator, the event’s host and an online platform founded four years ago. The group is dedicated to advancing Passive House through events, training, advocacy, and project showcases.
His own firm, New York-based Ingui Architecture, has been building Passive House projects for more than a decade. The firm has completed, he said, about a dozen Passive House buildings and is working on at least 10 more. This includes Manhattan’s first certified Passive House (completed in 2016), the first Passive Certified LEED House, the first Passive House in a landmarked district (in Brooklyn Heights), Ingui’s own (Passive House) townhouse, which he uses as a tool for publicizing its possibilities, and, recently, a renovated Cobble Hill townhouse for Chad Dickerson, executive coach and former Etsy CEO, and his family.
That four-story, masonry clad residence reveals key Passive House trademarks. Insulated both inside and out (the roof, for instance, is covered with outboard insulation, while all so-called “thermal bridges,” allowing unwanted heat or cold to get inside via conduction, have been disrupted) it boasts extra-large windows and skylights that let in more natural light while still not increasing heat gain (thanks to triple-pane glazing), uncluttered walls (thanks to fewer vents and radiators), and spacious interiors.
But it’s what you can’t see that’s more important. Dickerson says his family only uses their heat for about five or six hours every winter, while the residence always maintains a constant temperature, with no cold spots. There’s virtually no sound pollution, and air, purified by an electric ERV filter system, is virtually dust free. “It blows my mind just how good the air is in this house all the time,” noted Dickerson.
“It’s changing the quality of peoples’ lives, definitely,” added Chris Benedict, another Passive House pioneer who first caught onto the trend around 2005.
“I was hearing that there were these buildings in Germany that didn’t have boilers!” she said. “How can this be?”
One of Benedict’s first Passive House projects was Knickerbocker Commons (2014), an affordable housing project in Bushwick considered to be the first mid-size Passive House apartment building in the US. Among many innovations, the structure is clad in a geometric pattern of EIFS (Exterior Insulation Finishing System) panels, which serve simultaneously as cladding and insulation, assuring a constant temperature and removing the risk that condensation or other problems can occur inside the walls. The project offered roughly 70%t energy savings while costing about the same as typical construction.
Back at Reimagine Buildings ’24, more Passive House projects reveal that while the approach can cost more upfront, it balances out in the long term. Costs vary according to building type and market, but many Passive House projects cost only about five to 10% more to build, while generally paying for themselves in energy savings in two to five years.
“Applying Passive House is a no brainer,” said Nina Lynch, CEO at affordable housing developer Xylem Projects, a mission-driven New York real-estate firm, who showed off her firm’s upcoming Carmen Villegas Village, a 28-story, 100% affordable senior housing development in East Harlem being built to Passive House standards. She says the project’s cost increase has been projected at only 1.5 percent of total construction costs, while the operational savings will be $70,000 a year.
Passive House is also becoming a popular marketing tool — always a sign of a movement’s success. As they did with LEED a few years ago, designers and developers are now actively advertising their passive house bona fides. Handel Architects’ 691-foot-tall Winthrop Center in Boston, recently certified by the International Passive House Institute, is being touted as the largest passive house office in the world. (A typical class A office building in Boston, says its developer Millennium Partners, uses 150% more energy.)
ARO’s Khalil Gibran International Academy and PS 146, a 46,000 square foot facility containing a Spanish-language elementary school and Arabic-language high school on Flatbush Avenue in Downtown Brooklyn is promoting its status as one of the largest passive house education projects in the United States. (It’s also the first Passive House certified public school in New York.) When it opens this fall, the project, said ARO principal Stephen Cassell, will use less than a third of the energy of a typical New York public school. The biggest challenge, he said, was “tracking every seal, every joint, every condition” for such a large project.
And Passive House is ripe for innovation. At Reimagine Buildings ’24, designers and builders showed off modular, prefab, and all-electric passive projects, passive house retrofits, and new appliances like advanced heat pumps that can make passive house buildings more efficient.
While Passive House has long been promoted in a bottom-up manner — through passionate groups and ambitious developers, designers, and builders — the top down method is gaining steam, as governments start to force the issue. For now the leader on this front is Massachusetts. That state’s Department of Energy Resources last year launched a “Specialized Opt-in Code,” in which participating municipalities would require multi-family buildings equal to or greater than 12,000 square feet to achieve Passive House certification. (Boston is one of the many cities that have adopted this code.)
The Massachusetts Clean Energy Center (MASSCEC), through its Passive House Design Challenge, has funded Passive House demonstration projects, provided incentives for Passive House certification, and supported Passive House training.
In New York, Passive House regulations are still developing, but new legislation like New York City’s Local Law 97 require such strict energy performance that Passive House is close to mandated. The New York State Energy Research & Development Authority (NYSERDA), meanwhile, has promoted the movement through incentives, project funding, and programs like the Buildings of Excellence competition, which recognizes and rewards low carbon emitting multifamily buildings, many of them Passive House.
The Passive House Institute’s Grove-Smith added that other leading locations include Vancouver, where zero emissions targets have all but assured Passive House implementation, and Scotland, where the government has introduced legislation (not yet passed) to integrate Passive House standards at a national level.
Ingui notes that as cities and countries continue to shoot for aggressive emissions goals, and Climate Change worsens, Passive House will play an even more critical role. “I would say there’s no way to reach those goals unless you reach Passive House standards,” he said.
Of course passive house techniques don’t stand alone in this mission. They almost always dovetail with other green building guidelines, like LEED, Net Zero, the Living Building Challenge, etc.
“It’s really just about designing better buildings,” Ingui said.
Sam Lubell is editor at large at Metropolis and co-author of the “Phaidon Atlas of Never Built Architecture.”
