Trees, shrubs and flowers could soon dot the roofs of certain new
construction projects across Toronto, if City Hall gets its way.

a proposed bylaw before the planning and growth committee next week,
the city would require a "green roof" on any office building or retail
plaza bigger than 5,000 square metres (about 53,000 square feet), as
well as on most condominium buildings higher than seven storeys.

retail dimensions are about half the size of a regular Canadian Tire
store, said Jane Welsh, the city's acting project manager for
environmental planning. Green coverage of a roof could vary between 30
and 60 per cent, depending on building size.


Green roofs are
touted as a key element in Toronto's environmental effort. Benefits
include smog reduction, less stormwater runoff and an advantageous
cooling effect on summer temperatures.

"It's a fairly bold move,"
said Welsh, noting that the only Canadian municipality with a green
roof bylaw is Port Coquitlam, B.C.

Toronto can unilaterally impose such a bylaw because of its special powers under the City of Toronto Act.

But response has been mixed. Developers would prefer to keep the concept voluntary, and worry about the added cost.

roof proponents, including Deputy Mayor Joe Pantalone, argue the
proposed bylaw doesn't go far enough because it leaves out schools,
non-profit housing and factories.

"If Toronto wants to be a
leader, then lead" and don't deal in half-measures, said Steven Peck at
Green Roofs for Health Cities, a non-profit industry association.

"I don't understand why businesses in the public realm have been exempted."

Other jurisdictions may cite Toronto's example to exempt many classes of buildings, Peck argued.

roofs can act much like parks to reduce the "urban heat island" effect,
in which built-up areas become several degrees warmer in summer than
surrounding areas. That contributes to smog and raises the energy bill
for air conditioning.

While green roofs cost more to install – an
extra $10 to $40 per square foot – they can double its life by
providing shelter from extremes of cold and heat.

The insulation also brings energy savings, winter and summer.

"We have serious reservations about this bylaw," said planner Steve Daniels at Tridel, whose condo projects would be affected.

bylaw requires outdoor amenity space in condo towers, he noted, while
green roofs must be irrigated and cannot be walked on for the first two

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