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2007 Wastewater

City of Toronto

Making Green Roofs Happen

Population: 2,503,281

In late 2006, a green roofs pilot project — the first of its kind in Canada — funded the construction of 16 green roofs on a mix of public and private buildings in the city of Toronto. The project was the result of more than 18 months of research and consultation by the City of Toronto on green roofs. The initiative began in early 2005 when the City of Toronto, Ryerson University and a provincial centre of excellence produced their Report on the Environmental Benefits and Costs of Green Roof Technology for the City of Toronto. That report and a November 2005 discussion paper, Making Green Roofs Happen, laid the groundwork for the green roof strategy adopted by Toronto city council in February 2006. Under a pilot program, the city supported the creation of almost 3,000 square metres of new green roofs. The city looks forward to reaping the benefits of green roofs, including reduced stormwater runoff, lower energy demands, beautification of the city and reduction of the urban heat island effect.


The population of Toronto, Canada's largest city, is expected to grow to three million by 2031. As in all large urban centres, the natural landscape is covered with hard, non-permeable surfaces. The abundance of concrete and asphalt affects the city's water and energy systems, its air quality and the quality of life for its citizens.

The non-permeable surfaces in urban environments reduce the capacity for rainwater to be absorbed and this puts increased pressure on a city's stormwater systems. In Toronto, high levels of stormwater runoff can overwhelm the city's sewer capacity. Some beaches in the city are closed as often as 30 per cent of the time each summer due to high bacterial (E. coli) levels. The quality of drinking water can also be affected by high stormwater runoff.

The sun's rays are absorbed when they hit a city's non-permeable surfaces. The resulting heat buildup, known as the urban heat island effect, causes summer temperatures in the city to rise a few degrees above the temperatures in the surrounding countryside. High summer temperatures, reduced air quality and "smog events" cause exhaustion, illness and even deaths in vulnerable populations such as the elderly, children and those with asthma.

As Toronto's population grows and as summer temperatures rise because of climate change, the city will experience greater demands for energy and water services. Toronto Hydro has already reported that the transformers supplying the city's electricity can reach capacity during peak periods each summer. During heat waves, Toronto has had to encourage citizens to conserve and reduce their use of water.


  • The $200,000 Green Roof Pilot Program administered by Toronto Water from May to October 2006 received 18 applications, of which 16 were successful. The total area of the green roofs to be built by the program will be 2,950 square metres when all roofs are completed. The program is being evaluated in 2007 and it is expected that Toronto Water will implement a sustained grant program later that year.
  • A website created by the city to support the pilot program received more than 16,000 hits in 2006. Many requests for information both from within the city and elsewhere were sent to the e-mail address on the website at
  • In July 2006, city council adopted a green development standard to guide construction of city-owned buildings and those of its agencies, boards and commissions. This standard, which includes specific requirements for constructing green roofs, will encourage more sustainable development on a voluntary basis in the private sector.

Lessons Learned

  • SET UP A STEERING COMMITTEE. Joe D'Abramo, the manager of policy and research for the city planning division, says if he had to do the green roofs project again, he would create a steering committee of interested people. "If we'd had that at the beginning of the green roofs project, it would have helped us understand people's concerns and interests better, right from the beginning."
  • FOCUS ON BENEFITS. The study conducted by Ryerson University is a model that any municipality could use in investigating its own green roof possibilities and benefits, says D'Abramo. "I think it's important to focus on what the benefits would be and then to promote green roofs on that basis."
  • INFORM THE PUBLIC. D'Abramo says he was "astonished" at the community interest in green roofs. Public consultation was crucial and the level of interest from across the city helped get the message out that the city was serious about green roofs. According to Jane Welsh, the acting manager, environment, city planning division, the website helped tremendously with the city's public education campaign, providing information and gathering comments about green roofs. In addition, a leaflet informing people about the grant pilot project worked well.

Partners and Collaboration

  • FCM's Green Municipal Fund
  • Green Roofs for Healthy Cities
  • National Research Council
  • Ontario centre of excellence created by the Ontario Ministry of Economic Development and Trade
  • Representatives from the green roof industry, the building and construction sector, property owners, and building managers
  • Ryerson University
Page Updated: 21/12/2015