In 1991 Wolfgang Feist (German Wikipedia Link) a physicist from Darmstadt Germany built the first passive heated home. Now the estimate is that 15,000 homes across Germany and Scandinavia have been built with the innovations Feist pioneered.

What’s different in a passive homes is ultrathick insulation very sophisticated doors and windows in an airtight design. That means virtually no heat comes out or cold getting in. The heat that is needed can come from simple warming by the sun, heat from appliances and the people and pets living inside. There is a provision for adding heat but the systems are small and used infrequently. The added energy efficiency adds about 5 to 7 percent to the construction costs in Germany.

In the U.S. designers and architects are specifying better insulation and high efficiency appliances plus adding energy with solar panels and wind turbines in an effort to close the utility bill gap that high efficiency can add to mortgage payments. A $100 per month saved in utilities can equal more investment in the home.

The passive approach may be seeing more acceptance world over. The early attempts at tight homes suffered from stagnating air and susceptibility to molds as humidity would climb and air would settle to stillness. But now passive homes are being built with an ingenious central ventilation system. Inside air is expelled as outdoor air is drawn in with an exchange of the heat now up to 90% efficiency.

Architect Nabih Tahan with 11 years of experience in Austria is building his family a passive home in Berkeley California. He is also heading up a group of 70 San Francisco Bay area architects and engineers working to encourage wider acceptance of the standards. “This is a recipe for energy that makes sense to people,” Mr. Tahan said. “Why not reuse this heat you get for free?”

Wolfgang Hasper, an engineer at the Passivhaus Institut in Darmstadt says, “We’ve found it’s very important to people that they feel they can influence the system.” The newest systems offer three settings, one down for being away; one up to circulate air for lots of occupants and the normal one.

These are really clean comfortable homes. All the air from the outside is passed through HEPA filters. The internal temperature stability keeps the walls, objects and other items at a steady, uniform temperature.

Most interesting is that in Germany the market is growing. Passive is popular as many more people are aware of the advantages. The doors, windows and ventilation systems and other parts have migrated to off the shelf markets for the do it your self crowd. New construction costs are dropping with the added market volume.

But in the U.S. the prices are still much higher meaning construction would be higher than the falling 5% seen in Germany. Then there is the retrofit problem. In many U.S. homes no provision for forced air ventilation is available to retrofit.

The Passivhaus Institut 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.

Research is looking into the issues that are more American in nature, the cooling from air conditioning where a heat exchanger could be used in reverse, to keep cool air in and warm air out. Then there is the site issues, as passive needs correct positioning to get a sun facing wall for a heat driver.

Then the last issue is the size. Passive works best at 500 square feet per person a comfortable while not expansive mansion feeling.

On the other hand, above we read Tahan say, “Why not reuse this heat you get for free?”

Exactly. It is surely cheaper to transfer out stale air from a very tight house than to reheat or re-air-condition the air. It would be no huge matter for most forced air heating and air-conditioned homes to be fitted with an indoor to outdoor circulator as a worthy addition to a energy conservation program with goals of reducing heat loss through more insulation better windows and doors. I expect that the door and window quality level could even justify an increase with a few passive techniques added in.

Plus, these techniques could go a long way to making geothermal home heating smaller so making them much more affordable.

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