21st-century angle on ancient ideas provides massive energy savings in low-tech fashion
Back in an era of bad haircuts and awful disco music, homebuilder Hugh Heron tried to market a seemingly great idea. But, in keeping with the tastes of the times, it flopped.
Heron, then with Tartan Homes in Ottawa, helped build a group of houses that employed passive solar technology – a cost-effective way to slash dependence on traditional energy sources.
“We developed lots with a southern exposure,” Heron explains. “The houses were not square to the street, but at an angle. This angle was enough to put people off and these were the last homes in the development to sell.”
Heron, now president of Heathwood Homes and a partner in the Heron Group of Companies in Toronto , laughs when he looks back. He also emphasizes that “the world has changed since 1978.
“People have always been willing to spend more for granite (countertops), but now solar is starting to come into people’s lexicons.”
Heron was far from alone in being ahead of his time; others have been well aware of passive solar’s potential for decades. But the projects have tended to be small-time, usually in custom homes. The idea never really caught on with the mainstream construction industry.
Passive solar involves two essential components, says Mark Salerno, GTA district manager for the Canada Mortgage and Housing Corp. (CMHC).
“First, you need to look at an energy-efficient building envelope, creating a blanket around the house,” he says. “Then you design it, or site it around the sun.”
Strategies for passive solar do not involve any mechanical systems, which is why it is so cost-effective. Instead, traditional building elements are used, along with landscaping for summer shade and windbreaks,
Comparing the costs of passive solar homes with traditional construction is not easy, says Mario Kani, president of Toronto-based Sustainable Edge Ltd., which has been involved in such design for 25 years.
“Most passive solar homes are custom, not tract houses, so you’re looking at things like high-performance windows and extra drywall, which have a five- to 10-year payback,” Kani says. “The extra cost really depends on the design.”
He says passive solar maximizes the amount of glass on the south side of the building, meaning trees may need to be cleared to allow the sun to penetrate during the cooler months.
“You (also) have to consider the degree to which you allow the sun to come into the house, to avoid overheating in the spring and summer,” he says, adding that there has to be an overhang to stop excessive light. “Glazing on windows is important and some glazes even catch the heat on the north side.”
Kani says that open-concept homes work best for passive solar because natural convection carries the warmer air around the space. But he goes on to say that a mass is needed to absorb the heat and keep the temperatures lower in hot weather. This mass, or storage area, could be created from triple drywall sheets, masonry room dividers or a heat storing fireplace.
Then there’s the crucial siting and angle of the house not a big problem for a custom home, but for a builder in the tract business, it can mean rearranging the whole subdivision.
It’s those headaches and a few other lingering questions that leave Heron uncertain about whether he would build such a subdivision like the one he tried nearly 30 years ago. “I think we’ve a lot to learn and a lot of questions to ask,” he says. “It’s a lot more difficult than it sounds.”
U.S.-based architect Debra Rucker Coleman, who has been developing passive solar homes since 1985, does not agree.
“This is not rocket science,” says Coleman, who’s based in Alabama but finds most of her clients are in Canada and the northeastern parts of the U.S.
“Indians were building houses on south-facing cliffs (centuries ago). But when I was in Ottawa and Calgary to speak about passive solar, it seemed as if houses were built closer together than in the U.S. Nobody is using the space in between … it’s dead air. No sun can get through, which means there is more heat loss.”
Equating passive solar to trigonometry, Coleman says that the angles of the sun to the horizon are critical to planning an efficient passive solar home. In winter climates, for example, the sun would be at a much lower angle during the day so the easements, or open area between the home and sun, have to be much greater than places with southern climates.
In 1998 just north of Orangeville, Kani’s Sustainable Edge designed and built a passive solar home that is heated entirely by passive solar and a wood-fired masonry stove. To help keep the sun from penetrating in the summer, Anthony Ketchum, owner of the Ketchum House, has concord grape and northern kiwi vines growing on a trellis on the southwest side.
The temperature never falls below 10C and is often above 18C in this 1,600-square-foot two-storey home.
In a CMHC report called Low-Impact Housing-Ketchum House, this passive solar home was compared with a traditional home of the same size, shape and age in Toronto .
The differences in energy use are startling – the total electrical load for the conventional home is about 15,825 kilowatt hours a year. The Ketchum House runs on about 500.
Anthony Ketchum says it cost $145 a square foot to build his home, which “was a revelation for me in so many ways.
“It’s mind-boggling the amount of energy we burn to achieve indoor temperatures that we can achieve naturally,” he says. “The thermal mass keeps the temperature cool in the summer and warm in the winter.”
Possibly more mind-boggling is that this concept doesn’t qualify for government incentive programs (even though Ontario Hydro once tried one for passive solar the early 1980s).
It’s a disappointment to Sandy Nelson of Kincardine, who wants to build an energy-efficient home in a couple of years, when her daughters are finished high school. In the meantime, she’s researching passive solar because “it is the one thing you can do that doesn’t cost much.
“I’m willing to spend a bit more if I can do something for the environment. I can compromise in other ways, like a smaller home.”
Nelson is puzzled that passive solar hasn’t caught on in a time when green issues seem to be on everyone’s lips.
“I drive through southern Ontario with new eyes since I have been in house-planning mode,” she says. “And when I see the new crops of subdivisions sprouting up everywhere, I notice that the developers seem to be completely oblivious to how to harness the sun’s energy passively. So many garages take up all the southern exposure, and so many homes have huge picture windows to the west which will make the room unbearable in the summer.”
The only incentive for passive solar design is CMHC’s 10 per cent mortgage insurance rebate for energy-efficient homes bought by people who cannot come up with a 20 per cent down payment on the house. Mortgage insurance is required in these situations, so CMHC’s Salerno explains that for a $300,000 home, with 5 per cent down, this rebate would give the owners $800. Energy-efficient homes also qualify for a longer amortization period, which lowers monthly costs.
Salerno says these financial tools give developers a “distinct advantage,” though he agrees with Nelson that more needs to be done. “I think we’ve gone through a long period of time where we’ve relied on mechanics to regulate our indoor environment,” he says. “For one reason or another, we haven’t considered our free resources.”
Now, however, with higher energy costs and a bigger focus on the environment, Salerno says developers need to look at downsizing mechanical equipment, which he also thinks would “be good for their bottom line.
“I’m frustrated we’re not further along, but I do feel the building industry is open to this. Like a large ship, this industry doesn’t turn on a dime. It requires a calculated approach.”
Heron, meanwhile, has done his calculations and thinks that – like disco – passive solar might not ever be worth resurrecting for tract housing.
“With passive solar, the developer has to want to accommodate the lots so they have southern exposure,” he says. “It’s rather tricky because with the angle the houses impact one another.”There is a startling difference in energy usage.”