The Robertson Building

Green roofs provide a myriad of environmental and social benefits to residents of urban settings including:  

•    increased amenity space for urban residents
•    space for urban food production
•    increased space for species conservation
•    promotion of biodiversity
•    improved quality of life
•    increased longevity of roof membranes
•    noise reduction in city buildings
•    increase in property values
•    air contaminant mitigation
•    reduction in urban heat island effect
•    peak energy savings – particularly in summer
•    stormwater runoff benefits – quantity and quality, and,
•    aesthetic improvements for urban landscape

The total available green roof surface area across the City of Toronto is about 5,000 hectares (50 million sq meter).

In order for key economic benefits to accrue in a city like Toronto,  it is important that the following design parameters be met:

•    a green roof should cover a significant portion of the roof,
•    the planting media should have uphold a saturation potential where the maximum runoff coefficient is 50%, and,
•    the planting media should be at least 150 mm. deep  

Green roofs with less depth may be recommended for retrofit roofs although structural engineering is a recommended part of any green roof design team.