Air-Tight and Fresh

In 2016, the couple (who have young children) moved into their new Passive House. They chose the lot for its south exposure, which can be challenging to find among Calgary's residential lots. They wrapped the basement slab and walls in 8 inches of expanded polystyrene (EPS) foam.

They also installed a poly-vapor barrier below the slab and a water-proof membrane on the concrete. Fully wrapped to eliminate any thermal bridges, Crawford adds, the slab has an R-value of 35. The basement is also fully finished, as they rent it as a second suite or accessory dwelling unit.

Above grade, for the main level and the loft, the homeowners decided on a 2x6 wall with six inches of rock or mineral wool insulation and HardiPlank siding, bringing the walls to R-42. These choices, which resemble conventional wall construction, helped the couple secure their permits, pass city inspections, and find the right framer for the house. The roof has 16 inches of fiberglass for an R-60 value.

For most of the year, despite the Canadian climate, Valgardson has said, "we can get away with a 1500-watt heater—that's basically a hairdryer." On frigid days, the couple uses electric-resistance heat—"which we might change to a heat pump in the future," Crawford says—to bring the house to a comfortable temperature. A natural-gas instant hot-water tank provides hot water. The couple decided on Klearwall Passive House Certified windows. In the loft, those windows bring in light and heat.

While the house is air-tight, two Zehnder ComfoAir ERVs provide ventilation to the suite and upper levels. "We don't have a furnace," Crawford says. "The ERV exchanges moisture and heat; it's the lungs of the house. The ERV continuously filters and balances the fresh air. It exhausts air from the kitchen and bathroom, and recovers moisture from the air to preheat incoming cold air."

"The more windows you have on the south, as well as glazing with high solar gain, results in 50 percent of the heat coming from the sun," he explains, "but in the shoulder seasons, when the overhangs let sunlight into the house, there are days so sunny the house overheats. Also, in the summer, my overhangs weren't as long as they should have been."

Unlike in Germany, he continues, "In most of North America, especially in Calgary, it's very sunny." The family's solution? "We're bringing the overheating number down to 5 or below by adding shade fabric to the windows."

While Valgardson and Crawford designed and built their Passive House for maximum energy efficiency, they've experienced additional benefits. "We've found, by living in the home, how comfortable and quiet Passive Houses are. The background noise is the house is about 20 decibels, which is about the same as breathing. The indoor air quality is excellent, as is the light. In fact, the comfort becomes almost palpable when you live in a passive house."

Valgardson and Crawford took a permaculture design course, two food forest courses, and a class on building a rocket stove. As a result, they transformed their front yard into a 1,900-square-foot food forest. They used food scraps, leaves, cardboard, and wood mulch to prepare the area. The fruit trees and berry shrubs came from propagating plants from cuttings and by getting plants from friends. On the south side of the lot is the family's vegetable garden. All of the irrigation comes from harvested rainwater stored in a 5000L tank. Crawford says: