We have covered the building of our "green home" extensively in this blog; all along we have only occasionally mentioned the Passive House method, on which our housed design is based. The concept is still very new in the U.S., and we wanted to show rather than tell. But now the cat is out of the bag: today's New York Times has a front page story on how the Passive House works: by conserving warmth from the sun, appliances, and even residents' bodies.
The first Passive House was co-originated by Dr. Wolfgang Feist, a German physicist, in 1991. Now there are over 15,000 of these homes in Germany and Scandinavia, and the European Parliament is proposing that all new buildings meet passive house standards by 2011. NOTE: "In Germany, passive houses cost only about 5 to 7 percent more to build than conventional houses." -NYT
The key components of a passive house are:
- Super-insulated building envelope
- Triple-glazed, super-sealed windows
- Insulation under the foundation slab; even the finished concrete floors are not cold in winter
- The interior walls are the same temperature, resulting in no drafts
- Houses are sited to allow for maximum solar heat gain, e.g., windows are larger on the southern side of the house (in the Northern Hemisphere)
- Heat is conserved so that it takes the equivalent of the energy used by two hair dryers to heat the home on the coldest day of the year
What about ventilation, you ask?
"New passive houses use an ingenious central ventilation system. The warm air going out passes side by side with clean, cold air coming in, exchanging heat with 90 percent efficiency....'The myth before was that to be warm you had to have heating. Our goal is to create a warm house without energy demand,' said Wolfgang Hasper, an engineer at the Passivhaus Institut in Darmstadt." -Elisabeth Rosenthal, New York Times
In the U.S., the passive house concept has been advanced by Dr. Katrin Klingenberg at E-co Lab in Urbana, Illinois, and by Marko Speigel, of Conservation Technology International, in LaFox, IL. We learned about the concept at one of Marko's presentations at the Chicago Center for Green Technology. More information at the United States PassiveHouse Institute here.