“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.