Germany Builds Houses That Use Almost No Energy to Heat

Architects in Germany and other countries are designing “passive houses” that have extra-thick insulation and special windows and doors so almost no heat escapes and almost no cold seeps in.
Passive House
Jonas Risen
A “passive house”
in Darmstadt, Germany
This design allows the homes to be warmed not just by the sun, but also by the heat from appliances and from residents’ bodies. So far, the New York Times reports, an estimated 15,000 passive houses have been built worldwide, most of them in Germany and Scandinavia. Earlier attempts at building sealed solar-heated homes failed because of stagnant air and mold. But passive houses use a central ventilation system that allows warm air going out to pass alongside clean, cold air coming in, allowing heat to be exchanged with 90 percent efficiency. “The myth before was that to be warm you had to have heating,” says Wolfgang Hasper, an engineer at the Passivhaus Institut near Frankfurt. “Our goal is to create a warm house without energy demand.”