A retired chemical engineer, his wife and architect son are collaborating on a 2,860-sq. ft. house in an Edmonton, Alberta, suburb they hope will become the first in the province to win certification from the Canadian Passive House Institute (CanPHI).
Cottonwood Passive House, as the Zeibin family is calling it, is the first post-retirement project for Jim Zeibin, a chemical engineer who spent his career in the oil industry.
“Working in the oil industry meant that we moved around a lot,” Emilie Zeibin wrote in a blog about the project earlier this month. “Jim was tired of living in houses that leaked, had cold windows and were expensive to heat.”
So he decided to build a comfortable house that didn’t use much energy. Initially attracted to net zero energy houses that were being constructed in Edmonton, Jim eventually decided that route would be too expensive. His son David, an architect, suggested he look at the Passivhaus standard and the two later took a week-long course in Vancouver to learn more. David, a LEED accredited professional who holds a degree in engineering physics as well as architecture, then signed on as designer.
The project is described in an unusually well illustrated blog that includes photos taken at various stages of construction.
Double-stud walls and plenty of insulation
The house is being built on a corner lot in a new subdivision of Fort Saskatchewan, about 30 minutes northeast of Edmonton. Like all Passivhaus projects, it has far more insulation than a conventionally built house and will be carefully air-sealed to meet the stringent Passivhaus requirement for air leakage.
“Architectural controls imposed by the land developer largely dictate overall aesthetic themes to achieve a consistent neighbourhood character,” a blog entry on the design says. “While somewhat at odds with basic sustainable lifestyle choices (e.g. requirement for an attached two-car garage), the outcome still proves to be an environmentally high-performing design that is expected to achieve official Passive House Certification.”
Exterior walls are insulated to R-75 with a combination of Roxul mineral wool and fiberglass batts. The roof is insulated to R-94. The concrete foundation is insulated with 12 in. of expanded polystyrene insulation (EPS), applied to both the outside of the foundation and completely around the footings, roughly R-48 but higher in some spots.
Exterior, above-grade walls incorporate a 2×6 structural inner layer and a 2×4 outer layer on 16-in. wide plates (strips of OSB). Studs, which are on 24-in. centers, are connected with strips of 3/8 in. OSB. On the inside of the 2×6 wall, 5/8-in. OSB sheathing, sealed with Siga Rissan tape, is the air and vapor barrier. A separate 2×4 wall on the interior, insulated with fiberglass batts, provides room for wiring and plumbing, leaving the OSB air barrier unscathed.
The roof is framed with raised-heel trusses and insulated with 30 in. of blown-in cellulose. The windows are triple-glazed.
Heat will be provided by a natural gas boiler and small, wall-mounted radiators, Jim says. The house also will have a heat recovery ventilator.
Construction costs at $175 per sq. ft.
In all, he expects construction costs to be about $500,000, or about $175 per sq. ft. Emilie Zeibin writes in her blog that construction costs will be about 20% higher than standard construction.
One difficulty has been locating tradespeople willing to try new construction techniques, she says.
“Already familiar with this method, Jim has been more surprised by how long this process is taking,” Emilie writes. “Since this method is fairly new in Canada, it took a bit to find people in the trades willing to try something unconventional. It seems that a lot of the trades are hard to reach and even harder to get a quote from for something this unusual.
“In near desperation, Jim contacted Peter Amerongen of Habitat Studios for assistance. As it turns out, the trades that had been working with Peter Amerongen on his highly efficient houses (some of them Net-Zero), have been open to our project.”
The Zeibins hope to move into their new house in March 2014.