In late May of this year, the City Council of Toronto passed a law mandating that all new development above 2,000m² of Gross Floor Area be equipped with a green roof. The law will apply to new building permit applications submitted after January 31st, 2010 for residential, commercial, and institutional buildings, whereas the cut off is January 31st, 2011 for industrial development. This mandate is the first of its kind in North America, and will likely serve as a precedent for more to come. The issue is important and relevant because it is an example of government using its direct regulatory power to instate environmental improvement as opposed to market based approaches.
Toronto’s Green Roof Bylaw specifies a certain percentage of the rooftop required to be “green” in relation to the size of the building. For a building with a Gross Floor Area of 2,000 – 4,999 m2, the amount of available roof space should be 20% covered by greenery. Similarly, a GFA of 5,000-9,999 m2 constitutes a green coverage of 30%, and so on. Not surprisingly, developers are unhappy about this law because estimates show that this requirement has the potential to add upwards of $150,000 to building projects. Nevertheless, the long term monetary and environmental benefits outweigh this one time cost, making it fairly cost-effective.
This mandate is a great step in the right direction for two important reasons. First, green roofs offer many benefits to the environment, such as reducing rainwater runoff, filtering heavy metals out of rainwater, and vast energy savings. Green roofs reduce heating needs by adding mass and thermal resistance value, as well as cooling needs by evaporative cooling. In addition, if they are glassed in, green roofs can act as passive solar heat reservoirs and can reduce the city’s average temperature during the summer. Second, this mandate shows to the public governmental efforts to move towards more sustainable living. The idea of living sustainably should be solidified into the minds of the public so that we can learn to incorporate environmental consciousness into our lifestyles. In this regard, the green roof mandate is a step in the right direction as it will increase awareness of environmental issues as well as what is being done to address them.