Huffpost Green

PASSIVE HOUSES: Using "Recycled Energy" -- And No Furnace

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In trying to cut back on energy, some folks will crank the thermostat down and buy blankets. Why overwork the furnace?

But one German city has come up with a more radical solution called passive houses that cuts out the furnace entirely:

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 design style has made its way to the United States, too. An architect in Berkeley, Calif., has designed a passive house for himself:

Tahan explained that "free" heat produced by household appliances is carried by air inside the house to an energy recovery ventilator, which blows the air outside, but not before transferring the heat contained in the outgoing air to incoming fresh air.

It is most practical to use the Passive House design when constructing new buildings or remodeling homes that need drastic renovations, Tahan said.
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"By doing smaller insulating renovations, you can improve energy consumption and you'll definitely make a difference," he said. "But to get to Passive House standards, you really have to either rip out the outside or the inside of the house."

Here architect Nabih Tahan explains the design:

More on Nabih Tahan's passive house:

* A mechanical ventilation system, with an air to air heat recovery component, is installed to simultaneously bring in fresh air and remove the same amount of stale air.

* The stale air leaving the house is carrying the "free" heat. It goes through the heat recovery ventilator, and transfers the heat, to the incoming fresh air, before it leaves the building.
* The cool, exterior fresh air comes into the heat recovery ventilator, picks up the "free" heat and goes into the home warm.
* A conventional heating system is not necessary.

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