Gardens on roofs are pretty, a cool perq and maybe a
cure for what ails us

It’s hot up here. Standing on the roof of the John Street Pumping Station behind the Skydome, the view for miles is concrete and glass: highways, condos and parking lots baking in the sun, heating up the city. Lake Ontario hardly looks inviting and the few scrawny trees dotting the street below don’t provide much shade. At the foot of the city, there is little relief from the summer sun.

“You can smell the traffic,” says Kaaren Pearce, standing on the roof, surveying the smog hovering over the Gardiner Expressway. “We really have the chance to change the air quality up here.”

Soon this spot will be several degrees cooler. Pearce is standing on the 9,168-square-foot plot that is about to become Toronto’s newest green roof. Her company, Elevated Landscape Technologies, is designing and installing the roof, which in a few weeks will be covered in sedum plants and wildflowers.

The station’s newly greened roof, like the 100 or so others in the city, will have far-reaching benefits.

Green roofs absorb storm water and filter polluted runoff before it ends up in our lakes. The plant leaves suck pollution out of the air and cool the rooftop and surrounding air considerably. And while one cool roof will not make much of a difference to people sweltering on the street below, it will be more proof of what green roofs can do.

By definition, green roofs are contained green spaces on top of human-made structures. Green roofs are more complicated than simply creating a potted plant garden on a roof. Low-maintenance plants are grown in a multi-layered lightweight system that is, in essence, an extension of the roof. The system includes a root-repellent membrane to prevent plants from rooting in the roof, a drainage system and a growing medium that is lighter than the soil used on the ground.

The details don’t sound sexy, but green roofs are one of the most innovative and cost-effective ways cities can start to repair the ailing environment. Green roofs have been proven to quell the effects of the urban heat island, the result of sunlight reflected off concrete and other reflective urban materials, which can make summer air in dense cities up to 10 degrees hotter than in rural areas. More energy is used to cool buildings and more air pollution is created in the form of smog. Green roofs keep buildings cool, and, if planted en masse, could cool the whole city by several degrees in the summer.

They are hugely popular in Europe — 10 per cent of flat roofs are green in Germany, 12 per cent in Switzerland — and have started to make their way onto urban agendas in North America. And now that the City of Toronto is officially and financially backing a study of green roofs, Toronto may finally be able to get a leg up in the market.

The city’s Official Plan calls for the development of green-roof strategies– the goal is to green 6 per cent of the city’s flat roofs over the next decade — and some form of a green-roof task force has been in effect at City Hall since last fall. At the end of June, Toronto received $40,000 from the environmental arm of the Federation of Canadian Municipalities to form a round table to study green roofs and ultimately develop the policies and incentives for companies to start greening.

Though Toronto has been studying green roofs for some time now, beginning with demonstration projects at Eastview Neighbourhood Community Centre and City Hall, senior planner Jane Welsh says they still need to collect data. “Our objective is to understand what the measurable benefits would be to the city,” she says.

Green-roof owners never tire of touting their aesthetic and environmental benefits. And it’s not a hard sell — if you can get up to see one of them (most green roofs aren’t publicly accessible).

Mountain Equipment Co-op has a 10,000-square-foot rooftop garden on its King Street store. The garden helps cool the store and cuts down on air conditioning costs. You can book a tour at the store, climb up a ladder and through a hatch in the roof to see the high-tech garden, where grasses, flowers and mosses maintain themselves, cool the air and insulate the store below.

There’s a green roof at York University, and the Quad at Ryerson University is considered a green roof, one that grows grass for people to sit on. The Royal York Hotel grows all of its herbs for the kitchen in 15 beds on the 14th floor roof.

The owners of 401 Richmond installed a green courtyard on the 4th floor deck, to keep the air cool and provide green space for the building’s tenants. Lush flowers and plants bloom and provide a home for misplaced city bugs. Now The Morgan, an overlooking condo across the street, is thinking about doing the same.

So why is the city researching instead of building?

“We already know that plants will clean the air, clean the water and clean the soil,” says Pearce. “It’s not rocket science, just go to work.” She doesn’t think the city’s research project is going to give the green-roofs biz the boost it needs. “What’s really going to make a difference is when governments offer incentives or tax breaks,” she says.

In Europe, there are bylaws: governments tax water runoff, so people green their roofs. New York City, along with NASA and Columbia University, are looking at comprehensive green roofing for all of lower Manhattan. Portland, Oregon, is poised to become a leader by implementing a major green-roof investment program related to storm-water management. There are supportive words in the Toronto’s Official Plan about green roofs, but nothing to help private owners invest; no density bonuses or financial incentives.

“Hopefully the work of the city’s environmental round table will do the same type of thing for Toronto,” says Steven Peck, Executive Director of Green Roofs for Healthy Cities, North America’s trade association for the green-roof industry (landscape architects, contractors, etc.).

The big challenge is to establish the private benefits, which are typically long-term and insufficient to convince building owners to invest in green roofs, Peck says. For one thing, green roofs cost more to install — almost double the price of a regular roof. But green roofs can also save money: roofs will last longer, heating and cooling costs will be reduced, and food can be grown on them. And the government announced in May that buildings with green roofs may even qualify for funding programs for energy-efficient buildings.

“It’s not that green roofs aren’t being implemented in Toronto, they’re just being implemented slowly,” Peck says. “I would say we are still in the top five cities [in North America], but we are losing ground.”

And as with most environmental initiatives, embracing green roofs means reforming our thinking. Peck suggests thinking about rooftops as part of the city’s infrastructure, not just something that can pretty up the top of a building: “As public tax payers, why not invest in roofscapes just as we do in bridges and roads?”

Dave Robinson, MEC’s environmental-responsibility coordinator, also thinks it’s time to pay attention to roofs. “What wasted space,” he says, standing on MEC’s roof watching the sun beat down over bare building tops. “If you can just put green on these roofs, it would make a difference. If half the roofs in Toronto were green, we could swim in Lake Ontario.”

Now wouldn’t that be cool?

BY NICOLE COHEN