Project Profile

TD Living Roof

Project
The replacement of the existing conventional roof with a new extensive green roofing system on the landmark TD Banking Pavilion at the historic TD Centre in downtown Toronto.

Client
TD Bank Group

Green Reason’s Role
Project Managers and Sustainability Consultants. The team included the architects, structural, mechanical and electrical engineering consultants, roofing consultants, the landlord and the client’s green team.

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What was Done
As part of their on-going commitment to sustainability, TD Bank decided to go green when upgrading the aging roof of their flagship Mies Van Der Rohe Banking Pavilion at the TD Centre in downtown Toronto. The new vegetated living roof provides improved thermal resistance, reduces urban heat-island effect and limits stormwater run-off. In addition, the design preserves the existing roof grid pattern which is a protected element of the designated heritage building. As sustainable project managers, Green Reason worked with the team from initial feasibility investigations through to completion of the construction process.

The following was accomplished:

• The TD Living Roof is a low maintenance, extensive system with plant material growing in an aluminum structured grid.
• Bottomless planter boxes were used to recreate the grid pattern which is considered an integral element of the original Mies van der Rohe heritage building.
• The Creek Sedge Grass planted on the roof is a hardy evergreen native plant that has been selected for planting throughout the entire green roof. It is a very adaptive plant that is tolerant of the shade conditions of the TD Pavilion roof.
• The grass was chosen also for its consistent colour and growth pattern which will allow for the roof’s grid pattern to be maintained, protecting this important element of the heritage building.
• The TD Green Roof will retain and evaporate at least 50% of rainwater that it receives annually. The City of Toronto does not treat its stormwater, instead, the storm sewers are drained directly into Lake Ontario. Green roofs in the City serve as a treatment method improving the quality of water that goes back into the lake and reduce the amount of water being deposited into the lake by holding water and allowing it to evaporate back into the air.
• Green roof layers and additional insulation installed as part of the re-roofing double the R-value of the original roof to R-20.
• An irrigation system was installed on the roof to ensure the vegetation receives sufficient amounts of water. Due to the design of the building, the roof is not accessible for frequent visits that would be required for manual watering, so the irrigation system helps ensure the vegetation thrives and reduces the possibility of needing to replace the plants.
• To avoid over-watering, there is a sensor installed on the roof that will shut off the irrigation system when it starts to rain. This sensor will also reduce the time the sprinklers are on when the roof has not yet evaporated all the water received during previous rainfalls or irrigation.
• Although it is a myth that green roofs leak more than conventional roofs, there is a leak detection system installed just in case any leaks do occur. The system will locate the leak within a 3 meter by 3 meter area. This will greatly reduce the amount of mature planting that will need to be removed in order to repair a leak.
• Over 85% percent of the waste produced by the project was diverted from landfill by reuse or recycling.
• The recycled materials include several of the materials removed from the old roof: metal flashings, old roof pavers and gravel ballast. Plastic ramps required to move materials on the site during the project were also recycled.
• Most of the temporary materials used on the project will be reused multiple times. The hoarding was specially constructed in modular sections so it could easily be disassembled and reused several times on future projects. A portion of it is currently being used at the redevelopment project at 333 King Street East, while many of the pavers used as counterweights for the hoarding have been installed as roofing walkways on a school in Brampton.
• All pallets (skids) that arrived with delivered materials were returned to suppliers for reuse.
• A local company has transformed the TD graphic banners used on the hoardings into stylish and useful tote bags.

Results Speak for Themselves
The Living Roof was officially launched in June 2012. Following the inaugural media tours, the Globe and Mail called the green oasis in the middle of the financial district “surreal and thrilling.” Watch the time-lapse video of its construction.