How green are Toronto’s green roofs?
No one, it seems, has any clue.
That's because, explains University of Toronto professor Liat Margolis, while the 2009
Green Roofs Bylaw legislates green roof construction, the city never developed a way to actually monitor the ongoing effectiveness of what gets built.
"The green roof may be fine when it's inspected," says Margolis, "but a month later, it could have died.... Right now the city is explaining 'There is x million dollars in square feet in green roofs, therefore if we take the average performance in terms of water management and energy, we can assume that regionally Toronto is doing such and such performance.' But in reality, they may only doing 30 per cent of that because it could be that 60 per cent of those roofs are actually dead and we don't know it."
In short, though Toronto is certainly a green roof city—it's estimated that there are about 135 completed green roofs in Toronto and almost as many under construction—there's really no way of telling how 'green' these roofs really are.
That's just one of the problems that Margolis, along with her co-investigators, professors Robert Wright and Ted Kesik and their team of researchers, are working to address at the recently unveiled
Grit Lab (Green Roof Innovation Testing Laboratory).
The 2,000-square-foot lab, which runs out of U of T's
John H. Daniels Faculty of Architecture, Landscape and Design, and which sits atop the faculty building at 230 College Street, is a state-of-the art green roof lab, the only one of its kind in Canada. With 33 green roof beds and 264 sensors (so far), the GRIT lab serves double duty, both monitoring the effectiveness of different kinds of green roofs in the urban environments and simultaneously developing tools that will help to standardize that monitoring process.
The embedded sensors, says Margolis, "monitor and collect data such as humidity, wind, rainfall and temperature every two seconds." This real-time data collection will allow researchers to measure the efficiency of different types of green roof setups in terms of, among other things, energy efficiency, cooling, storm water management and biodiversity.
"Embedded remote sensing allows for various authorities, whether they are city officials or even private owners, or academic research facilities that are monitoring these things regionally, to make more of an accurate assessment," says Margolis.
"We're hoping this work will potentially influence or augment the green roof standard and green roof monitoring in the City of Toronto, and that it might also affect what industry is actually producing and promoting."
The second phase of the project, which will be launched later this year, will include the construction of a 50,000-square-foot green roof at the Tremco building in East York. As part of this second phase of the project, the GRIT team will introduce solar panels into their green roof model to understand how solar energy and green roof technology can work together.
Writer: Katia Snukal
Source: Liat Margolis, Assistant Professor of Landscape Architecture at the University of Toronto, John H. Daniels Faculty of Architecture, Landscape and Design