Rainbow Duplex isn’t British Columbia’s first certified Passive House; that honor goes to one built for the 2010 Olympics that was assembled in Whistler with parts from Austria. But Rainbow Duplex is the first Certified Passive House to be completely built on British Columbian soil, and it will open for public viewing this weekend. Designed by Marken Projects, the Passive House was constructed in the town of Whistler, about 75 miles north of Vancouver.
Homes that are forward-thinking and green aren’t new to the Vancouver area, nor to Whistler, a scenic and popular mountain getaway with its fair share of million-dollar homes. But here’s the thing: Rainbow Duplex doesn’t just meet the requirements for being a Passive House. It also satisfies those of Whistler’s Price Restricted House Initiative, which aims to provide affordable housing for the families and workforce that help make this famed ski-resort town go ’round.
It’s all about context, of course. Rainbow Duplex cost $250 Canadian dollars per square foot to build (at the current exchange rate, that’s about the same in U.S. dollars). In Whistler—one of the most expensive places to build in all of Canada, says Alex Maurer, director of Marken Projects—that’s affordable. The first unit measures 2,100 square feet, has four bedrooms, and sold for $600K; the other is awaiting a qualifying family. (In order to qualify for purchase, you have to live and work in Whistler.)
Like Passive House certifications in the US, those in Canada are tough to begin with, especially if you want to stay within budget. Add the restrictions of a northern climate and the designers had their work cut out for them. Only one of the duplex’s two units had southern exposure, says Maurer, so the other had to be shifted forward for solar gain. The small site posed additional challenges, he says, because Passive House standards favor multifamily to achieve the smallest footprint. "The smaller you go in terms of square footage," says Maurer, "the harder it is to meet Passive House standards."
Maurer worked for years on Passive Houses in Austria before he came to North America. Some of the materials and techniques that he brought with him and was able to use on Rainbow Duplex include:
- Subsoil heat exchanger. This sounds like geothermal at first—it uses a glycol solution and harnesses the earth’s temperature for both heating and cooling. It works in tandem with an HRV (heat recovery ventilator), and the pipes get buried 5 to 10 feet below ground instead of 150. The system is also called a ground-coupled heat exchanger
- Prefab panel system. Engineered wood panels with cellulose insulation allow the walls to breathe, says Maurer. But he cautions that attention to detail on the front end, down to the millimeter, is crucial. If the foundation isn’t 100% accurate, the prefab panels don’t fit.
- Cross-laminated timber decking. New to North America, this engineered wood product is light and strong. Maurer says it can be used in buildings up to 12 stories.
- Solar hot water. This is supplied through a vacuum pipe array on the roof.
Will there be more to come? "The interest is certainly there," says Maurer, who notes that there are currently five other Passive House projects in the works in British Columbia. "Rainbow Duplex helped us fine-tune the process," he says. "For private clients, we’re in the $180 to $200 per square foot range," he reports. "Now, we’ve got a competitive advantage."
Amy Albert is a senior editor at Builder magazine.