Canada’s First Residential Passivhaus Building
Rideau Residences, a duplex in Ottawa, was aiming for LEED Platinum, but ended up earning Passivhaus certification as well
Chris Straka, principal at Vert Design in Ottawa, Canada, apparently didn’t intend to meet the Passivhaus standard when he built his three-story duplex in the city’s Edinburgh neighborhood. Straka had consulted on dozens of green residential projects before starting his own company in 2006, and the main goal on this one, an infill project known as Rideau Residences (which overlooks the Rideau River), was to stay on budget while applying green building principals to most aspects of the project, from the deconstruction of a preexisting building on the lot to the reuse and recycling of materials to the implementation of conservation and energy efficiency measures in the new building.
Ross Elliott, owner of Homesol Building Solutions, which offers Passivhaus consulting and certification in the Ottawa area, points out on his company's website that colleagues told Straka that trying to build the duplex to the Passivhaus standard in the southeastern Ontario climate would be financially impractical. So he aimed instead for LEED for HomesLeadership in Energy and Environmental Design. LEED for Homes is the residential green building program from the United States Green Building Council (USGBC). While this program is primarily designed for and applicable to new home projects, major gut rehabs can qualify. Platinum certification, used conventional materials available in Canada, and tended to construction details as best he could to make the building energy efficient. He spent about $251 U.S. per square foot, which, he noted, is about 10% above the cost of a typical custom project in the Ottawa area.
Backing into Passivhaus certification
Straka hired Ross to evaluate the energy efficiency of the building, whose two units each offer about 1,500 sq. ft. living space, and the two discovered it performed to the Passivhaus standard. “My goal was to build a building I could be proud of, not necessarily to build a 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.,” Straka said, but added: “I knew that a very high performing building could be created using Canadian materials and mechanical systems.”
The project, which Ross says is the first residential project in Canada to earn Passivhaus certification (see our story on Austria Passive House), also includes radiant-heat floors, a geothermal heat pumpHeating and cooling system in which specialized refrigerant fluid in a sealed system is alternately evaporated and condensed, changing its state from liquid to vapor by altering its pressure; this phase change allows heat to be transferred into or out of the house. See air-source heat pump and ground-source heat pump. to supplement the building’s heat recovery ventilator, room for a cistern for rainwater collection, and a 1,200-sq.-ft. green roofRoof system in which living plants are maintained in a growing medium using a membrane and drainage system. Green roofs can reduce storm-water runoff, moderate temperatures in and around the building (by providing insulation and reducing heat island effect), as well as provide a habitat for wildlife and recreational space for humans. When properly constructed, green roofs can increase roof durability because the roof assembly’s air and water barriers are buffered from temperature fluctuations and UV exposure. with 12 in. of soil. A solar power system will be installed in the spring. According to the Vert Design website, the building has in fact been certified LEED Platinum. The website includes a slide show featuring many of the images highlighted here, as well as floor plans.
- All images Vert Design Inc.
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