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The glass-clad towers popping up in Toronto and Vancouver are not energy efficient, an expert claims.Kevin Van Paassen/The Globe and Mail

They've become impossible to miss in cities such as Toronto and Vancouver: giant condo towers that soar higher than even Bay Street's bank towers. But the building industry's fixation with glass-walled apartments is a looming energy efficiency nightmare, says one of Canada's leading building-code experts.

Ted Kesik, a professor at the University of Toronto, says the condo developers have exploited a loophole that allows them to erect towers clad in one of the least energy-efficient materials: glass.

Under current rules, developers of large projects can use sophisticated energy "performance" modelling software to meet energy targets – in effect, installing more expensive and ultra-efficient mechanical heating and ventilation systems as a "trade-off" against the use of uninsulated floor-to-ceiling windows, which builders see as a strong marketing feature, especially in tiny apartments.

In Northern European and Scandinavian countries, Kesik says, builders can't design buildings mostly clad in glass because their codes require robust materials and minimum insulation levels for the entire building envelope. "The Europeans don't allow [developers] to trade off."

But Joe Vaccaro, CEO of the Ontario Home Builders' Association, says the use of the performance standard has allowed developers to be "creative" with design, so they can use glass walls by deploying high-tech heating/ventilation systems. "It's the classic tension between the aesthetic and the functional," he says.

While new towers may meet present-day energy standards, Kesik says that those poorly insulated glass curtain walls, which are designed to last for half a century, will, over time, drag down the efficiency of those buildings.

To address that loophole, the Ontario legislature is currently considering legislation, now in third reading, that will force building owners and developers to disclose the actual energy performance of their structures, as is now done in jurisdictions such as Boston, San Francisco and New York.

"We're not cutting new ground here," Bob Chiarelli, Ontario's energy minister, says. "We have to catch up, and we have some good examples we can replicate."

But Vaccaro says his members object to the proposed reporting rules because developers can't control the way individual condo owners and tenants use energy.

"It doesn't matter how energy efficient your building is, if residents leave the lights on all day, it won't work," he notes. "I have no control over how the building is operated."

Ontario has Canada's toughest building code since the provincial Liberals began promoting green energy a decade ago. Chiarelli says the federal government and the provincial energy ministers recently convened a working group to harmonize and accelerate building-code standards for elements such as insulation and windows.

"We feel we can collectively make a lot of improvements," he says.

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