Adopted in 2009, the bylaw required the environmentally friendly roofs on residential, commercial and institutional buildings starting in 2010. Now, with the addition of industrial developments, all new buildings with a minimum Gross Floor Area of 2,000 square meters will be required to devote 20-60 percent of Available Roof Space to vegetation.
Aside from the pollution-scrubbing gift of rooftop parks, the greenery pays off in lower utility bills. Two American green roofs give an idea of potential savings. The Chicago City Hall installed a green roof in 2000 and now saves $5,000 a year. New York’s Con Edison Green Roof absorbs 30 percent of the rainwater that falls on it. It also reduces heat loss by 34 percent in winter and heat gain by 84 percent in summer.
Thanks to the bylaw, Torontonians have access to an urban oasis on City Hall’s podium roof. They can check out the gardens atop the YMCA of Greater Toronto. If they buy a unit in the Hugh Garner Housing Co-operative, they can enjoy the largest green roof in Canada. They can also visit other green roofs, such as those on ESRI Canada, Duca Financial Services, and Ryerson and York Universities.
Other cities considering green roof bylaws will find a lot of helpful resources on Toronto’s website. These include policy development, benefits of green roofs, bylaw language, and construction standards.
Developers have not all embraced the new bylaw, citing increased costs. However, the marketing pluses of a green roof like the one at the Toronto City Hall, coupled with utilities savings and environmental pluses, is gradually gaining converts.
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Photo of ESRI Canada's green roof from emmlalala via Flickr Creative Commons