Green roofs have many benefits. They not only insulate the buildings they shelter but also improve air quality and reduce runoff, easing sewer system loads and preventing associated overflow. They cool in summer, reduce heat loss in winter, and can support birds and other wildlife. Where green roofs top public buildings, they create public green space and parkland. Living roofs can even help cool an entire city in the summer by reducing what’s known as the “urban heat island effect,” where traditional roofing and paving materials increase the overall temperature of the air.
With Toronto’s new Green Roof Mandate, it is well on its way to becoming Canada’s Emerald City. Thanks to a City of Toronto bylaw that requires green roofs on new construction, green roofs will see a dramatic rise in Toronto’s skyline. Residences, commercial and institutional buildings over 2,000 square meters must have a roof that’s 20-60 percent “living.” Green/living roofs are partly or completely covered by vegetation, planted into a growing medium and sitting over a waterproof membrane. They often include structural support, irrigation and drainage systems, and can even incorporate greywater treatment ponds.
With the living roofs, much of the rain fall will now be “absorbed” into the plants and lessen the burden on waste water treatment and storm water volumes. For the city of Toronto, this means that there will be four to five more beach days. That’s good news for everyone. The question for us in City of Vancouver BC is, are we next?
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