UPDATED on April 16, 2015
More and more designers of high-performance homes are buzzing about a superinsulation standard developed in Germany, the Passivhaus standard. The standard has been promoted for almost two decades by the Passivhaus Institut, a private research and consulting center in Darmstadt, Germany.
The institute was founded in 1996 by a German physicist, Dr. Wolfgang Feist. Feist drew his inspiration from groundbreaking superinsulated houses built in Canada and the U.S., including the Lo-Cal house developed by researchers at the University of Illinois in 1976, the Saskatchewan Conservation House completed in 1977, and the Gene Leger house built in 1977 in Pepperell, Massachusetts. Aiming to refine North American design principles for use in Europe, Feist built his first Passivhaus prototype in 1990-1991.
Feist later obtained funding for a major Passivhaus research project called CEPHEUS (Cost-Efficient Passive Houses as European Standards). Conducted from 1997 to 2002, the CEPHEUS project sent researchers to gather data on 221 superinsulated housing units at 14 locations in five countries (Austria, France, Germany, Sweden, and Switzerland).
The standard sets a strict bar
The Passivhaus standard is a residential construction standard requiring very low levels of air leakage, very high levels of insulation, and windows with a very low U-factor. To meet the standard, a house needs:
- an infiltration rate no greater than 0.60 AC/H @ 50 Pascals,
- a maximum annual heating energy use of 15 kWh per square meter (4,755 Btu per square foot),
- a maximum annual cooling energy use of 15 kWh per square meter (1.39 kWh per square foot), and
- maximum source energy use for all purposes of 120 kWh per square meter (11.1 kWh per square foot).
The standard recommends, but does not require, a maximum design heating load of 10 watts per square meter and windows with a maximum U-factor of 0.14.
The Passivhaus airtightness standard of 0.6 AC/H @ 50 Pa is particularly strict. It makes the Canadian…