An Ottawa Family Builds, and Gets Ready to Leave, a Passivhaus

After six years of loving the Passivhaus they designed and constructed in Ottawa, Mark and Meghan Rosen are preparing for their next sustainable-living adventure. "We're project people," Mark proclaims. Mark is an architect and owner of Building Energy, a consulting firm founded by Meghan's father, Bruce Gough, who is considered the father of the ENERGY STAR Program in Canada. For him, building sustainably is a family business and a personal passion.

"We're ready for the next project," Rosen continues. "Maybe we're antsy because we've been cooped up during the pandemic. Maybe we're ready to build outside of the city. More than anything, though, we're excited to build again."

So, why should home buyers be interested in The Wander House, which the couple shares with their two daughters? "Let me count the ways!" Rosen exclaims. The home is built on an infill lot in the highly desirable Hintonburg neighborhood. "It's the third house we've lived in on the same block for last 12 years," Rosen says. The home was designed and constructed to the rigorous international Passivhaus standard.

Built with super-insulated walls, ceilings, and floors, the modern single-family home is air-tight and requires about 85% less energy for heating than a typical new home. The home also has a shallow geothermal ground loop, greywater-ready plumbing system, high-efficiency ventilation system, and heat pump hot water tank.

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The realtor calls it:

"The Tesla of homes—environmentally responsible yet aesthetically beautiful."

Adds Rosen: "Passivhaus is a quality way of building for the future. Plus, the house is an architectural gem separate from that. It's a high-performance, future-proof house, and it's beautiful."

Why Did The Rosens Build the Wander House Passivhaus?

When the couple bought the lot back in 2014, they were ready to build to Passivhaus standards. As a Passivhaus consultant, Rosen says, "I knew the international standard is the most rigorous for all the right reasons, including building with concerns about the planet and working with elements of construction that result in a healthy home. We decided we'd go all out and build a proof of concept."

The Ottawa climate, with its temperature extremes, not to mention an urban lot where site orientation is complex, posed significant challenges. "Still, if Passivhaus is the gold standard, we decided to walk the talk and show we could do it."

Initially, the Rosens considered using an off-site panelized prefab system. "The challenges of building during a Canadian winter are real," Rosen says. "The less time you have people working outside, the better." But the building partner wasn't ready, and the Rosens went with site-built instead.

How Did The Wander House Achieve Its Super-Insulated, Air-Tight Envelope?

The 2,000-square-foot home has three bedrooms and three baths, with a one-bedroom in-law suite (with separate access) in the walkout basement. Beneath the exterior cladding of unfinished eastern white cedar (which has weathered to silver) and HardiPanel siding are ICF (insulated concrete form) walls, 14 inches of EPS foam, 2.5 inches of wood fiberboard as a continuous layer, and four layers of rock- or mineral- wool batt insulation.

The foundation is a structural slab in a foam tray, with 16 inches of EPS foam under the slab at roughly R-70. Above grade, the home has hybrid double-stud walls insulated with mineral wool and wood fiberboard. The R values of the roof are at R-80 and one end and R-250 at the other, Rosen says, "because we have a wedge-shaped truss and didn't need to install an attic access hatch." The house has a zero-maintenance metal roof.

Rosen oriented the Gaulhofer triple-glazed windows toward the sun to the south to maximize exposure and collect as much passive-solar heat as possible during the winter months. The house doesn't have any windows on the north side, which is shaded and stays cooler. The electric, forced-air, 4-kilowatt duct heater is "about the size of a shoebox," Rosen says, "and uses about as much power as two hair dryers." 

Because of the home's Passivhaus design, heating demands are significantly reduced, Rosen says. "We didn't need to install any traditional large metal ductwork usually necessary for furnaces and air conditioning," he explains. "The only ductwork we have is for our ventilation system, which uses 3" flexible tubing easily run through the open web joists and inside 2x4 walls."

In addition to an ERV (energy recovery ventilator), the home has a shallow geothermal loop that preconditions ERV air and allows the ERV to run continuously without a defrost cycle. The system provides a constant supply of fresh-filtered air to the home. The Rosens have a greywater-ready plumbing system. In the future, a homeowner could easily reconfigure the system to allow water used from showers and baths to be reused to flush toilets, for example.

To learn even more about home, check out this podcast with the Conscious Builder.

What Luxuries Does Sustainable Design Bring to The Wander House Passivhaus?

The home's thick, super-insulated walls provide the family with space for built-in window benches and countertops. The family chose hardwood and ceramic tile floors throughout the house.

Choosing Passivhaus appliances meant balancing out cost, performance, reliability, aesthetics, and noise levels. By Astro Design Centre, the kitchen includes a Bosch dishwasher, which is quiet enough for the open-plan first level, a Bosch induction cooktop, and a Whirlpool convection oven. For ventilation, the Rosens selected a downdraft ventilator with a recirculating kit that sits in the island along with the cooktop. They also chose a ventless dryer that uses heat-pump technology, as well as a heat pump domestic hot-water tank.

"We've enjoyed living a more luxurious lifestyle in our Passivhaus, using a fraction of the energy to do so," Rosen says. Even though the family is ready for a new adventure in sustainable housing, leaving home will be bittersweet.

As Meghan Rosen wrote in the blog the family kept while designing, building, and living in the home, they enjoyed not having cold bedsheets at night or drafts through the walls and windows. "I could sit in our book-nook and read to the kids an inch away from a large window," she wrote. 

"My daughter's eczema improved, we didn't have any nose bleeds, and there were fewer colds and runny noses. When it came to the thermostat: we set it and forget it. The performance of the house faded to the background."

She adds that homeowners shouldn't have to sacrifice anything to live in a Passivhaus. "For [Passivhaus] to become more mainstream, we hope people will come to see that all the aspects of the Passive House are actually what makes it 100 percent livable." 

Article by:

Camille LeFevre

Camille LeFevre is an architecture and design writer based in the Twin Cities.