On May 27, Toronto adopted a mandatory green roof bylaw, requiring green roofs on commercial, residential and industrial property. In summary, the bylaw requires
Up to 50 per cent green roof coverage on multi-unit residential dwellings over six storeys, schools, non-profit housing, commercial and industrial buildings. Larger residential projects require greater green roof coverage, ranging anywhere from 20 to 50 per cent of the roof area.
The mandatory nature of Toronto's green roof law kicked up a storm of controversy, with many developers objecting to the increased costs.
According to the Globe and Mail
Steve Daniels, a development planner with the Tridel Group, said a green roof can cost $18 to $28 a square foot on a typical tall condominium building, meaning an extra $200,000 to $400,000, plus maintenance costs.
The question remains: how effective are green building mandates in improving environmental outcomes like improving energy efficiency, water use, etc. ? Are they better than incentives? Less effective? To date, there is no study available on the regulatory effectiveness of green building mandates. Such analysis needs to be undertaken soon before more requirements--which may or may not be the most effective means of acheiving environmental goals--are enacted.