The City of Toronto is considering a new green roof by-law that would make green roof installations mandatory on certain kinds of new developments with floor space more than 54,000 square feet. The proposal requires the greening of 30 to 60 percent of roofs, depending on building size. If passed, this would be the first green roof law in North America. According to the New York Times Green Inc blog, “similar requirements exist in Japan, Switzerland, Germany and France.” Steven Peck, President and founder of Green Roofs for Healthy Cities, an industry association based in Toronto, thinks the measure will pass. “We have a very broad base of support for this,” he said to Green Inc.
However, developers have opposed the measure, causing delays in voting on the by-law. Developers say green roof construction could add USD 18 – 28 per square foot to building costs. Green Inc says subsidies and by-laws aren’t the only mechanisms for spurring the development of green roofs: German municipalities now use new storm water taxes, which are levied separately from sewer taxes. “This distinction provides owners with an incentive to take steps to contain storm water on site, including installing green roofs. [The International Green Roof Association] I.G.R.A. says homeowners with such improvements can recoup 50 to 100 percent of the levy.”
Often, local or state governments provide grants or tax abatements to developers or building owners that install green roofs. Green roof supporters say they “improve insulation and roof life, absorb greenhouse gases and mitigate the urban heat island effect.”