"...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... 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 European Commission is promoting passive-house building, and the European Parliament has proposed that new buildings meet passive-house standards by 2011... The United States Army, long a presence in this part of Germany, is considering passive-house barrack... Nabih Tahan, a California architect who worked in Austria for 11 years, is completing one of the first passive houses in the United States for his family in Berkeley. He heads a group of 70 Bay Area architects and engineers working to encourage wider acceptance of the standards... 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... The Passivhaus Institut... 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... Because a successful passive house requires the interplay of the building, the sun and the climate, architects need to be careful about site selection... Most passive houses allow about 500 square feet per person, a comfortable though not expansive living space..."

No Furnaces but Heat Aplenty in ‘Passive Houses’ by By ELISABETH ROSENTHAL, The New York Times, December 26, 2008