Traditional Styling, Passive House Construction
One of the first new homes on the West Coast of the U.S. to earn Passivhaus certification blends seamlessly with much older homes in the neighborhood
Short of training as a Passivhaus consultant, one way to immerse yourself in Passivhaus technology and practice is to have a home built to the standard and then live in it. That’s what Sarah Evans and her husband, Stuart Rue, have done with their two-story project in Salem, Oregon, which broke ground in August 2009 and earned certification by Passive HouseA residential building construction standard requiring very low levels of air leakage, very high levels of insulation, and windows with a very low U-factor. Developed in the early 1990s by Bo Adamson and Wolfgang Feist, the standard is now promoted by the Passivhaus Institut in Darmstadt, Germany. To meet the standard, a home must have 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 W per square meter and windows with a maximum U-factor of 0.14. The Passivhaus standard was developed for buildings in central and northern Europe; efforts are underway to clarify the best techniques to achieve the standard for buildings in hot climates. Institute U.S. last month.
Planted on a roomy corner lot, the three-bedroom, two-and-a-half-bath house has about 1,880 sq. ft. of space divided almost evenly between the two floors. Evans and Rue hired local, green-minded experts to help them shape their vision for the house and get it in the ground: builder Bilyeu Homes Inc. and architect Nathan Good, both based in Salem. And like many other homeowners, designers, and builders who venture into the still-rarefied realm of Passive House construction, the couple blogged about the process and posted lots of photos.
The Evans-Rue house features advanced framed double-stud walls (just over a foot thick) and exceptional airtightness, having achieved .20 ACH at 50 Pascals in its last blower-door testTest used to determine a home’s airtightness: a powerful fan is mounted in an exterior door opening and used to pressurize or depressurize the house. By measuring the force needed to maintain a certain pressure difference, a measure of the home’s airtightness can be determined. Operating the blower door also exaggerates air leakage and permits a weatherization contractor to find and seal those leakage areas.. It also features exterior detailing that honors the traditional look of much older homes in the Northwest, including the 100-year-old house that, until about 12 years ago, had occupied the Evans-Rue lot. Evans credits Good with forging a compatible design.
“We wanted our house to fit in with the surrounding neighborhood and Nathan really made that happen,” she told Earth Advantage, a nonprofit green building and rating program based in Portland, Oregon, that certified the house with a Platinum rating, its highest, based on the building’s high level of energy efficiency.
“We have received two power bills constituting a little less than two months of electricity service at the new house,” Rue wrote on July 16. “We have averaged a tiny bit less than 14 kW per day. By way of comparison, the average American house uses about 30 kWh per day, according to the Department of Energy. Except for a few days last week, the weather since we've moved into the house has been very temperate, so we weren't expecting a huge bill. Still, it's nice to see such a low bill, especially considering that electricity is our only energy source.”
For more information on the house, see Net Zero Energy Homes Case Study 2: Rue Evans Passive House.
- Sarah Evans and Stuart Rue
Aug 16, 2010 9:04 AM ET