It’s sort of wild sometimes when a bunch of good people come together in one cosmos type of moment. Our friend Ken Edelstein at the Green Building Chronicle did an article on one of our clients, Jeff Dinkle of Eco Custom Homes about the Passive House Alliance. Cool!
Conceived 20 years ago in Germany, the Passive House has suffered a bit of rap during its second infancy in the United States. The basic concept — super-insulated, passive solar homes with tiny HVAC systems — is suited, critics say, only for cold climates.
Not so, insists a tiny vanguard of Passive House devotees who are determined to make Atlanta a center for the movement in United States. Among that cohort Tom DiGiovanni, an accountant and developer who’s spent the last few months helping to establish the Passive House Alliance — the advocacy and education arm of the movement in the United States.
In addition to DiGiovanni, longtime Sandy Springs homebuilder Jeff Dinkle sits on the Alliance’s national board.
“I think anyone who isn’t building to Passive House standards is building an obsolete house the day they complete it,” says Dinkle, owner of Eco Custom Homes.
That’s bold talk for someone who’s never actually been inside a Passive House. But Dinkle’s among a growing group of professionals nationwide who have gone through the official 75-hour Passive House training, taken a rigorous exam (which must be graded in both the United States and Germany), and begun searching for opportunities to build Passive House buildings — despite the fact that only 13 so far have been certified in the United States.
Dinkle says he’s long been frustrated by the less ambitious energy-efficiency standards of such certification programs as Earthcraft and Energy Star. He’s been building Earthcraft homes in Atlanta since shortly after the program was founded in 1999 and says his homes regularly score far higher than the Earthcraft program requires.
While the federal government’s Energy Star system requires a Home Energy Rating System score of 85 (or 15 percent more efficient than a standard house built to code), Passive House advocates say they typically come in around 15 or 20. In other words, they use less than a fifth the energy used by a typical house.
How is such extreme efficiency attained? Primarily through meticulous attention to passive solar design and to the quality of the building envelope. Wall insulation, for example, typically is five inches thick. And most American-built windows — even those rated as Energy Star — don’t cut it for a Passive House because the frames aren’t adequately insulated.
“Nowhere in the energy modeling [for LEED and other programs] do you measure the through-bolts that attach my deck to the house. And we wonder why our energy-modelng is failing,” Dinkle says. “Passive House is simple, simple stuff. It’s air-tight insulation. No thermal bridging.”
DiGiavanni went into more detail recently during an interview with Beth Bond of Southeast Green:
You actually are getting this level of energy reduction without relying on any of these kind of cool and kind of sexy, kind of of-the-moment technologies, that are also extremely expensive. What you’re really doing with a Passive House is you’re superinsulating the structure, you’re making your walls a little bit thicker, you’re using ultra-high efficency windows and doors, and you’re eliminating thermal bridging to the outside.
And then if you want to add solar or one of these other technological advances, you can downsize the size of the the system you needed so it doesn’t cost as much, but we rely on just really reducing the energy demand before we introduce these new things.
American Passive House enthusiasts tend to be industry professionals who don’t believe current green construction methods go far enough. DiGiovanni, a former chief financial officer for the Atlanta Development Authority who built houses in Seattle before that, got hooked after reading a magazine article. Dinkle first learned about it at a West Coast conference on eco-friendly building.
But the Passive House Energy Efficiency Standard actually is well established in Europe. It was founded Germany, where it’s known as Passivhaus. Some 25,000 residential, commercial and even industrial structures now are certified under the standard, which applies only to energy and not to other sustainable building criteria.
It was imported to the United States only eight years ago by Katrin Klingenberg of Urbana, Ill. The German-born artchitect built a handful of Passive House homes in that community and founded the Passive House Institute-U.S., an offshoot of the German organization.
I had the opportunity to visit a Passive House designed by Klingenberg in December. The Prairie-style building, owned by Margaret and Gregory Stanton of Urbana, has the solid, age-old look of a northern European house, with deep-set windows and blockish dimensions. The northern wall, facing the street, has relatively small windows; the southface features triple-glazed sliding glass doors, protected from the summer sun by an overhang.
The living room floor is made of beautifully finished concrete — thermal massing that sucks up passive solar energy that beams through the windows. To preserve energy, warm air from bathrooms and the clothes dryer are even vented back through the house’s air circulation system, rather than shot outside.
Most notable, however, may be the size — or lack of size — of the mechanicals. Inside a small closet on the second floor there’s an Energy Recovery Ventilator, or ERV, to pull fresh air slowly and steadily through the building and to regulate moisture. Mounted on a wall in the same room is a single, tiny mini-split heating and cooling unit.
There are two primary questions that critics have raised about building a Passive House in the Southeast. One is whether it makes sense to super-insulate a home in a region where heating bills can’t justify the expense. Dinkle answers that Passive House “the cheapest way” to get toward net-zero energy consumption. The extra materials and labor are at least partially offset by the more modest mechanical systems that the house requires.
Digiovanni, again in his interview with Bond, claims that Passive Houses in the United States are running 6-18 percent more expensive than conventionally built houses, but that in Europe — where the approach has become more commonplace — a Passive House only runs 3-3.5 percent more expensive.
The second question is whether such a tight house can be made comfortable in the South’s humid climate. After all, the traditional temperature regulation mechanism in southern homes was precisely the opposite of the Passive House approach: basically, open windows and large screened in porches allow a breeze to carry the heat and humidity away.
“It’s actually the antithesis fo a breathable house,” DiGiovanni says of the Passive House. But that tight envelop can make cutting down on the moisture a challenge.
Dinkle says there’s a simple engineering answer to making a Passive House comfortable: a “water-to-air coil” that uses a closed, ground-cooled loop to precondition incoming air and collect moisture before the air enters the ERV. It costs about $300.
So far, the Southeast’s only certified Passive House is a narrow, rental home built by Louisiana State University architecture professor Corey Saft on the edge of his property. (Dinkle, who serves on the Greater Atlanta Home Builders Association’s Green Builders Council, says he’s invited Saft to speak in Atlanta in April. Keep an eye on Green Building Chronicle for more details.)
But Dinkle, DiGiovanni and others are optimiistic about the program’s growth. Despite the tinyl number of certified projects, Passive House appears to be getting traction among thought leaders.
“We’re actually working with the U.S. Green Building Council right now to add Passive House by name as an alternative compliance path in their current version of LEED for Homes and as a main compliance path in the 2012 version of LEED for Homes,” DiGiovanni says. ““I think we’ll be in sync with the LEED program, so you’ll see that happen probably later this year.”
At a national Passive House conference last November in Portland, Oregon, the two Atlantans decided to get involved with the alliance, a new group formed there to serve as the advocacy and education partner of the Passive House Institute,
With his accounting and public sector experience, DiGiovanni took on the role of activing executive director and has been working to set up the alliance. His primary interest as a builder and developer is a affordable housing. So, at the same time, he’s working with Klingenberger on a 48-unit affordable housing project in Urbana.
Dinkle has a more modest ambition. He, like thousands of fellow homebuilders, saw hbusiness plummet during the recession.
“So you have time to think, and you have time to reinvent yourself,” he says. Now, as the market recovers and as word gets out that he’s one of the few Georgia builders to adopt a super-energy efficient method of homebuilding, Dinkle says he’s getting serious inquiries — partly from retirees on fixed incomes who don’t want to be on the hook for rising energy bills, partly from environmentally conscious early adopters.
“My goal,” he says,” is to build the first Passive House in Georgia.”