Autumn 2002 / Leading Edge
Green Roofs Are Cool

Rooftop vegetation helps maintain cooler interior temperatures


“Green” roofs made of an infrastructure that supports soil and plants are better than conventional roofs at keeping homes cool in summer, according to preliminary results from a U of T study. Professor Brad Bass of the Institute for Environmental Studies at U of T and Environment Canada’s Adaptation and Impacts Research Group, along with colleagues at the National Research Council’s Institute for Research in Construction, created an experimental roof – half of it a traditional flat roof, the other half a six-inch layer of soil and wildflowers above a special drainage layer and a root-repellent, waterproof membrane. The green roof maintained a cooler surface and interior temperature in summer and reduced storm water run-off. “The green roof acts as insulation,” says Bass. “The vegetation on the roof also provides shade and returns moisture back to the atmosphere, preventing a significant amount of solar energy from being absorbed by the roof.” Funding for the roof was provided by the Climate Change Action Fund and members of the roofing industry.


Reader Comments

# 1
Posted by Scott Anderson on March 29th, 2009 @ 10:55 am

You may want to check the Web before announcing research as leading-edge. Green roofs have been around for years. I suggested years ago to the powers that be at U of T that they look into installing green roofs on their new buildings, but to no avail (allegedly too expensive).

Marianne Khurana
Department of Physics
University of Toronto

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