The Robertson Building

In early 2006 City Council approved a budget reallocation of $200,000 to implement the Green Roof Incentive Pilot Program. The overall goal of the program is to encourage green roof construction in the City, resulting in a number of highly visible projects. It was expected to provide a grant of $10 per square metre (1$ per square foot) toward acceptable green roof projects to a maximum grant amount of $20,000. The program was open to all owners of private property in the City of Toronto irrespective of building size and type as long as the building is capable of supporting a green roof that meets the program requirements.  The pilot program ran from May to October, 2006 and is currently being reviewed and evaluated. It is hoped that the program will be reinstated next year and subsequently as well. Details of the Green Roof Incentive Pilot Program with respect to eligibility criteria and application procedures are posted on the City’s Green Roof Website www.toronto.ca/greenroofs.

For more information on green roofs or other environmental programs at the Robertson Building please contact: Beth Anne Currie 416.595.5900 x21

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.   

The City of 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) gathered to promote green roof development in the city. In 1999, this group was succeeded by Green Roofs for Healthy Cities, a not-for-profit industry association that supports green roof market develop, advocacy, and education in North America.

The City of Toronto has been an active participant in studying the economic benefits of green roofs as a sustainable design technique that can help to mitigate many urban environmental challenges. In 2004, in partnership with the Ontario Centre for Excellence in Technology (OCE-ETech) and the Federation of Canadian Municipalities, the City of Toronto contracted a team of Ryerson researchers to develop a cost-benefit analysis of green roof technology for the City of Toronto. The client wanted to expand their understanding of: the types of green roof technology currently, to measure the economic benefits of green roofs including any potential monetary savings to the municipality through the use of green roofs on a city-wide scale. The Ryerson team was made up of professors and graduate students, including Urbanspace Property Group's Environment, Health and Safety Coordinator, Beth Anne Currie. Beth Anne completed her masters in environmental science and management at Ryerson, and was able to share her thesis results on the air pollution benefits associated with green roofs to this report for the City of Toronto.

In June 2004, a 4,000 square foot, extensive green roof was installed over one half of the Robertson roof. The green roof, designed and installed by Gardens in the Sky, is supported by approximately six inches of organic, light-weight planting media with over ten species of Ontario native perennials planted into this special soil. These vibrant meadow flowers have thrived over the past growing seasons, despite the at times harsh weather they encounter in this elevated ecosystem, and provide a gorgeous addition to the urban landscape that can be viewed from the glass atrium and deck that completes this rooftop area.
Before the green roof was planted, a user-friendly common space needed to be created to allow tenants and visitors to enjoy the roof garden. An opening was created from the fifth floor and a new metal staircase was installed. Next, a solid wooden viewing deck was constructed to provide a platform for further construction and development -- in particular, for a spectacular glass atrium that surrounded the new staircase and elevator.

The City of Toronto announced recently that it will be allocating $200,000 of the budget to implement a Green
Roof Incentive Pilot Program.  The overall goal of the pilot program is to encourage green roof installations
across the City and promote a number of highly visible projects already in place.

The City was influenced in part by a recent Ryerson University green roof cost-benefit study (using data from the City's Wet Weather Flow Master Plan (2001)). This study showed that if 8% of downtown Toronto's flat roofs were greened there could be a potential savings of one to two dollars per square metre from stormwater runoff reductions. This economic rationale, along with other environmental benefits, provided the basis for establishing the pilot program, which will provide eligible property owners with a grant of $10 per square metre for acceptable green roof projects, up to a maximum of $20,000.

There's always something interesting to report when it comes to the living systems at the Robertson Building.
For this edition of the Pipeline, we're going to take you deep into the underworld of root systems on the green roof.  Typically, when a seed germinates, it plunges a strong primary or "tap root" downward into the soil. The
objective of a tap root is to grow deeply into the soil to anchor the new plant and access nutrients and moisture for energy production and photosynthesis. Plants with tap roots are difficult to transplant - think about the last time you tried to urge a dandelion out of the ground! Even if you break the top off, the long taproot stays in the
ground and can re-generate an entire dandelion plant all over again.