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Report on the Environmental Benefits and Costs of Green Roof Technology for the City of Toronto

Prepared For
City of Toronto and Ontario Centres of Excellence – Earth and Environmental Technologies (OCE-ETech)

Prepared By
Ryerson University Professors:
Dr. Doug Banting Professor Hitesh Doshi Dr. James Li Dr. Paul Missios

Students:
Angela Au Beth Anne Currie Michael Verrati

October31, 2005
Project Contact: Hitesh Doshi Dept. of Architectural Science, Ryerson University 350 Victoria Street, Toronto, Ontario , M5B 2K3 Phone: 416 979 5000 x6502 E-mail: hdoshi@ryerson.ca

Report on the Environmental Benefits and Costs of Green Roof Technology for the City of Toronto

Executive Summary
Report on the Environmental Benefits and Costs of Green Roof Technology for the Cityof Toronto Toronto has been at the forefront of organized green roof activity over the last several years. In early 1990’s volunteers under the Rooftop Garden Resource Group (RGRG) started to promote green roof development in the city. This has been taken over by Toronto-based Green Roofs for Healthy Cities, a not for profit organization, which carries out world-wide education on green roofs. TheCity of Toronto has been an active participant in studying wider use of green roofs as a sustainable alternative to meet many of the urban environmental challenges. In the past few years the City has shown leadership in promoting green roofs. In order to inform its actions, the City in partnership with OCE-ETech and the Federation of Canadian Municipalities, engaged a team of Ryerson researchers todevelop further understanding of: the types of available green roof technology, the measurable benefits of green roofs to the city’s environment, potential monetary savings to the municipality through use of green roofs, and minimum thresholds of green roofs that could be used for part of any incentives or programs. This report presents the findings on the municipal level benefits of implementinggreen roof technology in the City of Toronto. Beyond this report, which addresses the immediate needs of the City of Toronto in assisting them to formulate appropriate programs and policies, the Ryerson team has been charged by OCE-ETech to develop a generic technological solution that can be used to predict the costs and benefits related to green roofs. This work is ongoing and is not reportedhere. For this report, the Ryerson team conducted an extensive literature review to determine the benefits related to green roofs and, in particular, the quantification of these benefits. It also collected information on the types of buildings in Toronto and their geographic distribution. The information collected was modeled as a GIS database and used for aggregating the benefits on a city-widebasis. The Ryerson team also developed a method to compute the monetary value of the benefits. A survey of the existing green roof technologies and standards was carried out to inform the development of minimum requirements for green roofs. The findings of the work are presented in the following sections of the report: Section 1, about the study, provides historical background related to this work;Section 2, survey of research related to green roofs, provides the findings of the literature review on benefits of green roofs; Section 3, survey of types of green roofs and their standards, provides information on the different green roof technologies currently available and the performance standards pertaining to green roofs; Section 4, green roof benefits and costs for the City of Toronto,provides the details of the quantification of benefits of city-wide implementation of
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Prepared by Ryerson University

Report on the Environmental Benefits and Costs of Green Roof Technology for the City of Toronto

green roofs. The report ends with a summary and recommendation, in Section 5, which provides the recommendations, the minimum thresholds and guidance for further work. Of the...