The Height of Cool: Battling the Heat From U of T’s Experimental Green Roof

Sourced from The Toronto Star

From the fifth-storey roof of the University of Toronto’s new faculty of architecture building — plunk in the middle of Spadina Cres. — Robert Wright points north to the canopy of green that covers the city’s Annex neighbourhood.

Then he turns his gaze south, to Chinatown, where sprigs of more freshly planted trees are barely dotting the denuded jumble of offices, stores, streets and warehouses heading off toward Lake Ontario.

“That is what we eventually want that to look like,” the director of the faculty’s centre for landscape research says, tracing an arc with his index finger from north to south.

“We want the same kind of (green) coverage down there. Of course it will take a long time.”

But in these days of global warming, greening the city has become an urgent matter. And there’s a more immediate solution to Toronto’s carbon footprint problems growing happily at Wright’s feet.

Wright and his colleagues are now embedding the final pieces of U of T’s newest experimental green roof — a collection of 48 boxed, piped and wired plant beds that will come equipped with its own weather station.

Known as the Green Roof Innovation Testing Laboratory — or GRIT Lab — the facility is a follow-up edition to the one that’s topped the architecture school’s old College St. headquarters since 2010.

And while it will look specifically at the use of cistern-stored rainwater as a viable irrigation source for the rooftop arrays, it will also continue its predecessor’s search for ideal plant and soil combinations and investigations into the gardens’ potential to alter outdoor temperatures, moderate storm runoffs, save energy and attract pollinators.

“Every (flat) rooftop in Toronto faces south so they get maximum radiation up there,” says Wright, also dean of forestry at the school. “So whatever we can do to make more reflective surfaces or put vegetation up there will cool the environment around them.”

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