High-performance homes   (Page 1 of 3)

Why isn’t Canada spearheading the movement to build more sustainable homes?

By Monte Paulsen with photography by Grant Harder

Photo: Grant Harder

Open this magazine wide. Now picture a hole in the side of your house that’s just a little larger than the pages in your hands. Imagine the wind blowing through that hole.

The hole is real. If you were to combine all the cracks and crannies in a typical Canadian home, they’d add up to almost 1,400 square centimetres, roughly the size of 2.5 magazine pages. Combine the openings in all of Canada’s 12.9 million homes, and you’re looking at a hole 20 times larger than Parliament Hill.

Plugging that hole is the simplest way for Canada to save energy. Plugging the hole also saves money, creates jobs, cuts greenhouse-gas emissions and makes our homes more comfortable.

We know how to find the hole. Canadians pioneered the use of a tool that can measure the airtightness of a building. Natural Resources Canada (NRCan) has used this “blower door” to test more than 800,000 Canadian homes.

We also know how to fix the hole. Way back in 1977, we built a house so airtight and so well insulated that a hair dryer could have kept it warm through the winter — in Saskatchewan.

Yet despite the fact that buildings account for roughly one-third of our national energy consumption and the fact that we’re world leaders in smallbuilding energy-conservation technology, Canadians still haven’t plugged the hole. Most of our existing homes remain quite drafty, and most of our new homes fail to meet decades-old efficiency standards.

This year, however, more than a dozen high-performance homes will be completed in cities and towns across the country. These include homes built to the fast-growing Passive House standard, as well as net-zero homes designed to produce as much energy as they consume. This story is about the idea at the foundations of these homes — an idea that roamed the world for three decades before coming home like the prodigal son.

Builders have long known that heat claims the lion’s share of the energy consumed in Canadian homes: 57 percent of the total, compared with 24 percent for hot water, 13 percent for appliances and 5 percent for lighting. They’ve also known that heat escapes wherever air escapes, mostly under doors or around windows. But it wasn’t until the 1970s that builders became aware of just how much heat leaks through these gaps.

“We knew how to calculate the heat loss through walls and ceilings,” explains Harold Orr. “But when it came to air leakage, you licked your finger and held it up, then pulled a number out of the air.”

Orr is the no-nonsense son of a carpenter. He grew up in Vancouver, where his family lived in a squatter’s shack during the Great Depression. By 1959, he was working toward a master’s degree in mechanical engineering at the University of Saskatchewan. For his thesis project, he set out to develop an instrument to measure air leakage from buildings.

Orr’s first idea was to pump a house full of hydrogen and sample the escaping gas. This proved difficult — and potentially explosive. His next attempt, filling a house with sulphur hexafluoride, was time-consuming and expensive. A few years later, while working for the National Research Council, he joined efforts to compare indoor versus outdoor air pressure through the use of large fans and long ducts. Orr devised a simpler way to measure the airflow using a venturi nozzle and “a surplus fan from Princess Auto in Winnipeg” which was mounted in a piece of plywood that fit over a door.

The resulting blower door enabled Orr and his colleagues to quickly and cheaply measure air leakage. Similar instruments were being developed in Sweden and at Princeton University, in New Jersey. Within a few years, a standard measurement was agreed upon: the number of times per hour the blowerdoor fan would suck all the air out of a house at a prescribed pressure of 50 pascals (Pa). (Suck water about six millimetres up a soda straw, and you’re at 50 Pa.) The resulting metric was called “air changes per hour (ACH)” at 50 Pa. With gaps totalling 1,384 square centimetres, the average Canadian home leaks enough air to result in 6.85 air changes per hour at 50 Pa, or 6.85 ACH@50Pa.

In the wake of the 1973 Arab oil embargo, the Saskatchewan Research Council invited Orr to help design an energy-efficient home appropriate for the Saskatchewan winter. The oil crisis prompted many similar projects, with most focusing on new ways to trap solar heat within a more or less standard building. Working in the dark northern winter, the Saskatchewan team — led by engineer Rob Dumont — elected, instead, to design a radically more efficient building envelope. The Saskatchewan Conservation House, completed in Regina in 1977, was likely one of the first buildings to combine three key elements: superinsulation, extreme airtightness and a heat-recovery ventilator.

In an era when nearly all houses were constructed of four-inch-thick walls filled with R-8 insulation, the twostorey Saskatchewan house featured 12-inch-thick R-40 walls and R-60 roof insulation. (R values measure the insulation’s resistance to heat flow; the higher the R value, the more effective the insulation.) Likewise, single-paned windows were then the norm; this home had triple-glazed windows. The house also boasted extreme airtightness. Orr and his colleagues installed the vapour barrier themselves in an effort to slash air leakage. Most new houses at the time scored in the range of 9 ACH@50Pa; the Saskatchewan Conservation House achieved 0.8 ACH@50Pa. “At the time,” recalls Orr, “I think it was likely the tightest house in the world.”

Thirdly, to provide fresh air to the airtight house, the Saskatchewan team built an air-to-air heat exchanger. This device pulled in fresh (but cold) outdoor air through a series of baffles. Stale (but warm) indoor air was pushed out through the other side of those same baffles, and heat was transferred from the exhaust air to the incoming fresh air.

The Saskatchewan Conservation House had no furnace. Instead, it relied on a system that collected solar heat during the day, stored it in a water tank, then released the heat at night. All told, the house required less than a quarter of the energy consumed by a standard home of the time. Some 30,000 people toured the house. Its success led to the construction of more demonstration homes in Saskatoon. An article in a 1981 issue of Popular Science was titled, “Super-insulation: Saskatchewan leads the parade.”

That same year, the “house as a system” approach pioneered in Saskatchewan formed the basis for a new national building standard that required R-20 insulation, blower-door test results of 1.5 ACH@50Pa or better, the installation of a heat-recovery ventilator and the use of non-toxic materials. The new standard became a partnership between NRCan and the Canadian Home Builders’ Association. It was the toughest standard in the world at that time and presaged by decades the advent of green building initiatives such as BuiltGreen or LEED (Leadership in Energy and Environmental Design). The new standard was voluntary, but its authors intended for its gradual integration into the national building code. With their sights set on plugging the hole in Canadian homes by the turn of the century, they named the new standard “R-2000.”