Passive House: A glimpse of what's to come

The building of the Nanaimo Passive House is a significant step on several fronts, not the least of which it is the first multi-family, affordable-housing certified Passive House facility in all of Canada. Passive House construction is slowly emerging as a potential building method of the future. It is reported to achieve 80 to 90 per cent energy savings over traditional construction methods.

The Nanaimo Passive House project called for the construction of three blocks of ground-oriented suites, arranged around an open courtyard. This enables all of the 25 suites to have cross-ventilation and solar access. The simplicity of the building system reduces maintenance costs and energy consumption.

The Nanaimo Passive House project was designed by DYS Architects for the Nanaimo Aboriginal Centre. It was funded by BC Housing, providing affordable suites for youth, elders and families of the local aboriginal community in Nanaimo.

Chris Beaton, executive director, Nanaimo Aboriginal Centre, cites average monthly energy costs in the building as not exceeding $20 month for a three-bedroom townhouse. The building also includes bachelor, one-bedroom and two-bedroom units.

“The decision to seek Passive House Certification was clientdriven,” explains Karl Binder, project manager, Saywell Contracting Ltd. “The client weighed the benefits of lowered maintenance and utility costs with the slight increase in construction costs. Other factors that were considered were the health benefits to the occupants; the total absence of natural gas to the site; being able to prove that affordable housing for families could be built to the higher standard; and ease of maintenance with the finished buildings.”

In preparation for the undertaking of its first Passive House project, Saywell’s superintendent completed the Passive House Tradesperson Training Course — Building Envelope Specialization at the BCIT High Performance Lab.

According to Binder, there are several key differences in this emerging type of construction. These include the use of two-by-four framing members for cost savings; the application of insulation on the outside of the building — to a reduced depth of 6-inch batt insulation; all air/vapour/moisture protection on the exterior of the framing (to allow for interior and exterior finishing to occur simultaneously and to reduce the potential for mold, mildew and rot); superinsulation of the foundation; heat recovery ventilators (to retain the gathered heat of the day, while bringing in a constant supply of fresh air at low volume); triple-paned, thermal gathering, over-insulated windows; and multiple pressure tests of the building to ensure air changes per hour were under the required threshold of 0.6ACH for Passive Certification).

Dean Doney, project manager, Waywest Mechanical Ltd., got to experience the differences in Passive House construction firsthand. The company’s scope for the project included the plumbing and HVAC.

“I think this is the direction that our industry is going,” states Doney. “I think the industry will eventually have to move toward a ‘pay-forward’ model, where the cost to build is a little more but the result is less of a burden on our resources.”

According to Doney, the notable difference in the plumbing was the use of Sanden split heat pump water heaters. This was complemented by low water-consumption and water-efficient fixtures.

On the HVAC side, Doney cites the use of plastic distribution piping — three iches in diameter — and a move away from the use of rigid 90-degree angles used in conventional construction.

“This allows the easy flow of air to each room for both heating and air exchange, which is very important when your building is air-tight,” he explains. “The HRV for this project was a Zehnder ComfoAir 200, one of the most efficient HRVs on the market.”

Doney adds that the smaller piping and use of the non-angular layout provides an inherent design for easy air flow without restrictions, which means increased air flow without the need for more power.

The electrical work for the Nanaimo Passive House building was awarded to Osprey Electric Ltd.

“We were tasked with the complete electrical component for the project,” says Ken Kaktins, project manager, Osprey Electric. “The work was not too different from conventional projects; it was more a matter of the techniques that were used. For example, the project used heat pumps instead of conventional heating methods, like baseboard heating.”

One of the elements that did differ for the company, adds Kaktins, was that the floor systems were considered part of the building envelope.

“We had to mitigate the amount of penetration into the floor system as a result,” he says. “It took a bit more co-ordination but was easy to accommodate.”

Osprey had about four crew members on site for most of the job, supplementing them with another crew of that size when the work required it.

“I think that we will see more people moving towards this type of emerging construction,” notes Kaktins. “It is a new style right now but will eventually become the norm.”

“The building also became a teaching and touring site throughout the construction,” concludes Binder, who cites the visitors as including MPs, MLAs, mayors, city council members, Regional District of Nanaimo managers and inspectors, representatives from the Real Estate Board, architects, students and the heads of five indigenous housing corporations. “It was a very interesting project to work on — one that provided good learning opportunities and one that attracted a great deal of attention.”

By Melanie Franner, for the Vancouver Island Construction Association (VICA)