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Green roofs grow up
Gardens atop buildings keep homes cool and cut costs by serving as a natural insulation blanket
Innovative alternative offers long-term savings — and eliminates need to re-shingle every 15 years
Architects Janna Levitt and Dean Goodman have developed a reputation for building thoughtful, environmentally sensitive housing for individuals and communities.
When they finally got to build a house for themselves, they looked up for inspiration.
They were drawn to the idea of a green roof — essentially a garden in place of shingles. They'd suggested them for clients and had seen the benefits to the urban environment.
"We wanted to experiment with things we believe in," Goodman says.
For help, Levitt and Goodman turned to Terry McGlade, a landscape architect who's been installing these "Gardens In The Sky" — the name of his business — since 2000. His first garden was the wetland retreat on the roof of the Merchandise Lofts.
With summer temperatures and smog levels both on the rise, a green roof might seem a small step. But it's an idea that's catching on.
While green roofs have been gracing the Toronto skyline for five or six years, in Europe the idea is big. Stuttgart, Germany, for example, has more than 1 million square feet of green roofs, and in some parts of the city, green roofs are required by zoning law.
The appeal is both energy consciousness and cost. "They serve as a natural insulation blanket,," explains McGlade. "You can reduce cooling costs by 85 per cent."
The two-storey, two-bedroom Levitt-Goodman house doesn't even have an air conditioning unit. "We didn't need it," Goodman says. "Without the heat radiation from the roof, the upstairs is the same temperature as the main floor, and as soon as the outside temperature cools, so does the inside."
The quality of the air is a lot better, too. "Although nobody's really experimented with the carbon monoxide exchange rate, we do know a roof garden puts oxygen back into the environment" McGlade says. "The plants breathe in carbon monoxide and breathe out carbon dioxide. Photosynthesis. It's a wonderful world."
It's not cheap to install at $14 per square foot or more, but there are long-term savings. The National Research Council figures it takes five to 10 years for an energy payback, says McGlade.
In addition to the energy savings, the roof is there to stay — no need to re-do the roof every 15 years — and the life of the building is extended because the roof membrane isn't exposed to fluctuating temperatures and damaging ultraviolet rays. "This is something you absolutely have to take the long view on," McGlade adds.
As the green roof movement evolves in Canada, it is developing its own distinct Canadian style, McGlade says. "It's amazing how many plants there are that can take conditions of direct elements, so you can create pretty much any kind of garden you can think of."
At the Levitt-Goodman house, he planted a no-maintenance combination of sedums, grasses (one prairie grass, the other a woodland grass), coreopsis, equisetum, bergenias and hostas, which require watering only for the first year. ``We're not gardeners," Goodman says. ``We tend to kill things off in fact, so it was necessary to have something that could maintain itself.'' After the first year, the garden takes care of itself from rainwater and melting snow.
While a roof garden may sound simple — alternating layers of roof, drainage, soil and plants — McGlade doesn't suggest it for the do-it-yourselfer: The roof needs reinforcement and the layers need professional design and installation to allow for proper drainage, or the house may leak.
Although the roof was the starting point, Levitt and Goodman carried the environmental sensibility throughout the house. Being proponents of infill housing and increased urban densities, they've downsized from their previous 2,600-square-foot home by about 1,100 square feet.
Levitt says they now have "way more usable space — open-concept layouts and different levels helps."
With all the windows, there's lots of light. A central skylight floods the whole house with light. Lights don't need to be turned on until 9 p.m. even on foggy days.
The house is environmentally responsible in other ways. The open-concept layout, high ceilings and ceiling fans help air circulation.
Water is on-demand for heat and domestic use by being run through a boiler the size of a computer CPU.
There's reclaimed Douglas fir on the kitchen counter, and all materials are from local sources, including the pine siding and windows from a small Parry Sound company.
The house isn't just a workshop for environmental philosophy, though.
Levitt is as excited as any new homeowner.
She loves the tons of storage in her kitchen, the porcelain bathroom tiles that feel like grass cloth, the polished cement no-maintenance floors.
"We've waited a long time to do this, but it's getting there — it's really nice."
One of their favourite spots is the master bedroom overlooking the roof garden that'll be habitat not just to plants but to birds and butterflies as well.
The inspiration for this retreat was a tiny guesthouse at a friend's cottage where they stayed years ago.
"We wanted a bedroom exactly like it one day," Goodman says.
Sources
Levitt-Goodman Architects: http://www.levittgoodmanarchitects.comor 416-203-7600.
Gardens In The Sky: http://www.gardensinthesky.comor 416-531-1461.
by ALEX NEWMAN, SPECIAL TO THE STAR
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