Why passive houses need to become widespread

Even if I learned more than two years ago about the theory on passive housing for my Master’s Thesis at the Audencia Nantes Management School, the reality is little known to me.

Even if I knew such houses don’t need any heater it seemed too vague a notion. But an interesting article from the New York Times brought me a most interesting insight of such constructions.

The result is staggering and a lot of energy could be saved if such houses were to become widespread as they use 20 less energy than traditional ones.

Here are some extracts of the NYT article:

From the outside, there is nothing unusual about the stylish new gray and orange row houses in the Kranichstein District, with wreaths on the doors and Christmas lights twinkling through a freezing drizzle. But these houses are part of a revolution in building design: There are no drafts, no cold tile floors, no snuggling under blankets until the furnace kicks in. There is, in fact, no furnace.

In Berthold Kaufmann’s home, there is, to be fair, one radiator for emergency backup in the living room — but it is not in use. Even on the coldest nights in central Germany, Mr. Kaufmann’s new “passive house” and others of this design get all the heat and hot water they need from the amount of energy that would be needed to run a hair dryer.

(…) His new home uses about one-twentieth the heating energy of his parents’ home of roughly the same size, he said.

Architects in many countries, in attempts to meet new energy efficiency standards like the Leadership in Energy and Environmental Design standard in the United States, are designing homes with better insulation and high-efficiency appliances, as well as tapping into alternative sources of power, like solar panels and wind turbines.

The concept of the passive house, pioneered in this city of 140,000 outside Frankfurt, approaches the challenge from a different angle. Using ultrathick insulation and complex doors and windows, the architect engineers a home encased in an airtight shell, so that barely any heat escapes and barely any cold seeps in. That means a passive house can be warmed not only by the sun, but also by the heat from appliances and even from occupants’ bodies.

And in Germany, passive houses cost only about 5 to 7 percent more to build than conventional houses.

(…) “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. “This is not about wearing thick pullovers, turning the thermostat down and putting up with drafts. It’s about being comfortable with less energy input, and we do this by recycling heating.”

There are now an estimated 15,000 passive houses around the world, the vast majority built in the past few years in German-speaking countries or Scandinavia.

(…) The industry is thriving in Germany, however — for example, schools in Frankfurt are built with the technique.

Moreover, its popularity is spreading. The European Commission is promoting passive-house building, and the European Parliament has proposed that new buildings meet passive-house standards by 2011.

(…) Inside, a passive home does have a slightly different gestalt from conventional houses, just as an electric car drives differently from its gas-using cousin. There is a kind of spaceship-like uniformity of air and temperature. The air from outside all goes through HEPA filters before entering the rooms. The cement floor of the basement isn’t cold. The walls and the air are basically the same temperature.

Look closer and there are technical differences: When the windows are swung open, you see their layers of glass and gas, as well as the elaborate seals around the edges. A small, grated duct near the ceiling in the living room brings in clean air. In the basement there is no furnace, but instead what looks like a giant Styrofoam cooler, containing the heat exchanger.

(…) In Germany the added construction costs of passive houses are modest and, because of their growing popularity and an ever larger array of attractive off-the-shelf components, are shrinking.

(…) Dr. Feist’s original passive house — a boxy white building with four apartments — looks like the science project that it was intended to be. But new passive houses come in many shapes and styles. The Passivhaus Institut, which he founded a decade ago, continues to conduct research, teaches architects, and tests homes to make sure they meet standards. It now has affiliates in Britain and the United States.

Still, there are challenges to broader adoption even in Europe.

Because a successful passive house requires the interplay of the building, the sun and the climate, architects need to be careful about site selection. Passive-house heating might not work in a shady valley in Switzerland, or on an urban street with no south-facing wall. Researchers are looking into whether the concept will work in warmer climates — where a heat exchanger could be used in reverse, to keep cool air in and warm air out.

For more on this topic, please check the Wikipedia page on passive housing.