A city committee considered a proposed bylaw that would require roofs on new buildings with an area of 5,000 square metres or greater to be 30% to 60% covered by vegetation. The bigger the building, the more planted space it would have to have otherwise fines of up to $100,000 could be levied.
As drafted, the bylaw would cover mid-to high-rise condos, retail space and office towers, but exempt low-rise, large-scale industrial, nonprofit housing and public buildings such as schools.
But even as Toronto's powerful development industry was urging the city to slow down and keep green roofs strictly voluntary, local politicians were complaining the draft bylaw was too cautious for a metropolis vying to be the most environmentally minded on the continent.
Deputy Mayor Joe Pantalone, who helped bring the city's first power-generating windmill to the Exhibition grounds, said he was "disappointed" the first draft of the bylaw was so "tepid."
Pantalone asked city staff to come back in a month with a proposal that would include schools, low-rise buildings on "Main Street" and even private residences.
"Either we are the leading city in the world or we're the ones who looked in the mirror and got scared," he said.
BILD the Toronto and GTA Building Industry and Land Development Association was quick to urge city politicians to reconsider.
The association sent a letter to the city's chief planner expressing reservations and proposing a pilot project first instead of a full-scale bylaw.
"We have significant concerns with the city's proposal to require and govern the construction of green roofs. We continue to advocate that green roofs be implemented on a voluntary basis," it stated.
"If the home-building and development industry are provided with various incentives, this approach would assist the city with its objectives, while not forcing green roofs on those who may choose to use other forms of sustainable development for their projects."
Since his election in 2003, Toronto's hybrid-driving Mayor David Miller has put the environment front-and-centre on the municipal agenda, setting up a LiveGreen office to promote eco-friendly living, offering rebates for low-flush toilets, banning bottled water sales at city hall, taking on the coffee industry over the disposable cup and studying climate change within civic boundaries.
A new city report touts the environmental benefits of rooftops covered largely in plants and organic material as opposed to asphalt or metal.
These include "reducing the urban heat island effect and energy consumption, improving air quality and storm water management and creating opportunities for biodiversity and habitat creation and beautification of the city."
Steve Daniels, who sat on a green roof technical advisory committee representing BILD, said developers are interested in working with the city to create more green roofs. But he said they can add "hundreds of thousands of dollars... if not more" to the cost of a project.
"The range can be anywhere on the lower end from $18 a square foot to around $28 a square foot. It's somewhere in that range that we're looking at for an added cost," Mr. Daniels said.
"It's always a concern. Compounded with development charges, compounded with application fees that go up, it's a cumulative effect. So this is just another added cost that has to be factored in at the end of the day."
On top of that, he said there is trepidation about how the new bylaw, which derives its authority from the City of Toronto Act, would mesh with the Ontario Building Code and other city zoning requirements, such as those that call for outdoor amenities for high-rise condos. Those amenities often end up on the rooftop.
Stephen Upton, vice-president development planning at building giant Tridel, pointed out that once installed, the rooftop shrubbery has to be left untouched for two years to allow it to take root.
More information is also required about the longevity of green roofs and how much should be budgeted in a condo corporation's building fund for future replacement.
"I think there's still quite a bit left to be understood, digested and refined," Mr. Upton said. "Toronto green standards, those are things that shouldn't be mandated but should be encouraged."
But while the developers were balking at the bylaw, environmental groups were urging Toronto to move further and faster.
Steven Peck, president of the 10-year-old Toronto-based group Green Roofs for Healthy Cities, said the city's efforts could create jobs and be on the "leading edge" of the technology.
"We're very concerned that there's been a watering down of the requirements and we're concerned it will set a negative precedent for cities elsewhere in North America," Mr. Peck said, adding Toronto is "perched on the edge of really starting to get serious about implementing green roofs."
The issue will return to the planning and growth committee for further debate on May 6.