Work should be wrapped up this fall on a 1,895-square-foot home in Fort St. John, British Columbia, that is on track to become Canada’s most northern certified Passivhaus residence.
Fort St. John, a 16-hour, 760-mile drive northeast from Vancouver, British Columbia, was established as a trading post in the late 18th century, and it still sees plenty of people traveling through on the Alaska Highway. These days, Fort St. John calls itself “The Energetic City,” reflecting the region’s rich natural resources of oil, gas, and forestry.
The municipal motto also seems an apt description of the city’s plans to develop a mixed-use neighborhood including more energy-efficient buildings on a 91-acre parcel of city-owned property. The house nearing completion at 9904 94th Street is a sort of test kitchen where new technologies and construction practices could be worked out.
The city-owned house was designed with prefabricated wall and roof components by Marken Projects Design + Consulting, a firm specializing in high-performance buildings.
In addition to being the farthest north, Marken says the project also will become the first detached single-family residence in the province of British Columbia. Passivhaus construction, however, isn’t entirely new to the province. Germany’s Passivhaus Institut lists a “semi-detached house” built in 2012 in Whistler, which also was designed by Marken. And GBA’s Richard Defendorf described a two-unit house built to Passivhaus standards in Whistler in time for the 2010 Olympic Games in a blog post in 2009. That project also is listed as certified by the Passivhaus Institut.
A challenging environment for Passivhaus construction
Certified or not, meeting the Passivhaus standard for heat and energy consumption is no walk in the park in Fort St. John, which posts an average of more than 10,000 heating degree days a year and sees mid-winter temperatures plunge to 30 degrees below zero F.
Designers specified a two-layer wall system consisting of an inner 2×4 service wall filled with mineral wool insulation and an outer wall of 11 7/8-inch I-joists on 24-inch centers filled with dense-packed cellulose insulation. The wall assembly has an R-value of about 56. Offset I-joists and 2×4 studs minimize thermal bridging. (GBA senior editor Martin Holladay wrote about this home’s walls last year in an article called The Klingenberg Wall.)
A layer of 5/8-inch oriented strand board on the exterior side of the 2×4 wall provides the air barrier. Exterior sheathing consists of 5/8-inch fiberboard.
The slab assembly includes a finish floor of wood or tile over 1 inch of expanded polystyrene insulation (EPS), 4 inches of concrete, and an additional 11 1/4 inches of EPS insulation, for a total R-value of about 52.
Below grade, perimeter walls are Fox Blocks insulating concrete forms with an 8-inch-thick core of concrete sandwiched between layers of 2 5/8-inch thick EPS insulation.
Roof panels are made with 16-inch I-joists insulated with dense-packed cellulose plus a 2×3 service ceiling layer insulated with mineral wool, for an overall R-value of about 70.
As of the June 24, the results of blower-door tests for airtightness were still pending.
Mechanicals and other sustainable building features
The three-bedroom, 2 1/2-bath house is all-electric. Other building details provided either by the city or at a blog on the project include:
- Domestic hot water from a 50-gallon Rheem heat-pump water heater.
- A rooftop solar array of 12 panels with a total rated capacity of 2.8 kilowatts. Planners estimate the system will generate 3,500 kWh of electricity per year, roughly one-quarter to one-third of estimated demand.
- Heating and cooling with a Mitsubishi Mr. Slim ductless minisplit system. There are two heads, one on the first floor with a rated capacity of 18,000 Btu/hour, and another, rated at 9,000 Btu/hour, on the second floor. Marken estimates the heating and cooling costs at between $200 and $400 per year. The house also has a heat-recovery ventilator.
- Triple-glazed windows manufactured by Optiwin. Glazing in the Alu2Wood windows has an R-value of 7.8 and a solar heat gain coefficient of 0.52, according to Rogers.
- Sustainable building features include low-flow plumbing fixtures, regionally sourced and recycled materials were possible, lumber certified under the Forest Stewardship Council, and native landscaping and permeable paving
The city becomes the general contractor
The city had not intended to build the house itself, lead designer Ayme Sharma and Marty Paradine write in the Marken blog, but after the construction documents were complete a request for proposals drew only a single response.
“The construction market is so busy in Fort St. John that there were not many builders interested in taking on the challenge of building something new,” they write. “Developers in Fort St. John are most often focused on constructing single-family homes as quickly as possible to accommodate job growth in the oil and gas sector.”
The city wasn’t discouraged as much as it was motivated to show that Passivhaus construction was feasible in northern British Columbia, and that builders who knew how to pull it off would hold a competitive advantage.
Once the house is complete, the city will monitor its energy performance and use it for open houses for one year, then sell it.
“During construction, the project has already been used as a demonstration to teach the local building community about Passive House construction and low-energy building design,” the blog says. “There have already been signs of success in breaking down local preconceptions about energy efficient homes.”
No overnight conversion to Passivhaus
Fort St. John City Manager Dianne Hunter doesn’t expect this single Passivhaus project will convert either local builders or homebuyers to super energy efficiency overnight.
“It’s about baby steps,” she said, “starting slow.”
Fort St. John is located in an energy-rich part of the country where people aren’t expected to care very much about efficiency, she said, but that made it all the more important to the city to demonstrate otherwise as it looked for ways to develop the city-owned tract.
“We felt we had an obligation to show good stewardship of our resources,” she said, and despite some of its frustrations, the Passivhaus project was a good place to start.