Passiv Haus (Passive House)

Posted by Gennaro Brooks-Church

December 31, 2008

A “new” construction style coming out of Germany creates houses that barely need energy to run. They don’t even have heating systems. In the dead of winter they might need a little space heater but that is is. What is the secret? Here is a list from their site:

Compact form and good insulation:
All components of the exterior shell of the house are insulated to achieve a U-factor that does not exceed 0.15 W/(m²K) (0.026 Btu/h/ft²/°F).

Southern orientation and shade considerations:
Passive use of solar energy is a significant factor in passive house design.

Energy-efficient window glazing and frames:
Windows (glazing and frames, combined) should have U-factors not exceeding 0.80 W/(m²K) (0.14 Btu/h/ft²/°F), with solar heat-gain coefficients around 50%.

Building envelope air-tightness:
Air leakage through unsealed joints must be less than 0.6 times the house volume per hour.

Passive preheating of fresh air:
Fresh air may be brought into the house through underground ducts that exchange heat with the soil. This preheats fresh air to a temperature above 5°C (41°F), even on cold winter days.

Highly efficient heat recovery from exhaust air using an air-to-air heat exchanger:
Most of the perceptible heat in the exhaust air is transferred to the incoming fresh air (heat recovery rate over 80%).

Hot water supply using regenerative energy sources:
Solar collectors or heat pumps provide energy for hot water.

Energy-saving household appliances:
Low energy refrigerators, stoves, freezers, lamps, washers, dryers, etc. are indispensable in a passive house.