October 15, 2014 6:23 pm
Updated: October 15, 2014 6:31 pm

City planner wants to stop wind tunnels created by some skyscrapers


TORONTO – The city’s chief planner is all too aware about the wind gusts that have been created in isolated spots across the city because of the city’s tall condo buildings.

And she says in the coming months, the city will be taking steps to stop the wind tunnels.

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“We’ll be introducing, likely within the next 12 months, specific development permit bylaws in specific areas within the city,” Jennifer Keesmaat, the city’s chief planner said.  “[The winds are] a result of the built form, that’s absolutely true. This is a condition that we’ve created unfortunately.”

When the wind hits a tall building it can be pushed down towards the sidewalk where it swirls around and creates wind tunnels throughout Toronto.  It’s called the Venturi Effect or Downwash.

“As these buildings get higher, this vortex effect – as you have wind shedding off the sides of the buildings, create small little vortices that will have an influence at the ground level,” Dr. Paul Walsh, a professor of Aerospace Engineering at Ryerson, said.

It’s no secret that the city is building taller buildings, but at what cost? Toronto’s rapidly rising neighbourhoods are having a direct impact on the comfort of Torontonians.

“More and more we’re becoming like Chicago,  the windy city,” David Clarkson, the manager of Kit Kat Italian Bar & Grill on King Street said.

He said menus, chairs and glasses have been blown off of tables in recent years. The only reason they don’t blow into the streets is because they’re being weighed down by heavy plates.

The King Street patio used to bring in over $4,000 a day for close to two decades, Clarkson said. That is, until the condo boom hit.

Kit Kat doesn’t even put up their overhead awning anymore – the high winds cause it to sway dangerously.

“Overall I blame the city. The city’s the one who allows these developers to come in and do it – and just taken their word that they’ve done wind studies and here’s the proof that it’s affecting businesses in the area,” Clarkson said.

Global News used a wind-measuring device called a anemometer to measure wind speeds in downtown Toronto and clocked gusts between 30-45 km/hr at the southwest corner of the 55-story Four Seasons Hotel.

Wind speeds of less than 5 kilometres and hour were measured just north of that same building.

But not all tall buildings create wind tunnels. On dozens of buildings downtown, the tall portion is inset from the road considerably. The lower portion, often five to six storeys in height, is called a podium. It acts as a windbreaker – sending the downward gusts spiralling back up again.

“So here we are at York  and Bremner, surrounded by dozens of tall buildings. And yet, with the canopies, the wind is still very light,” Walsh said referring to the large glass canopies jutting from the perimeter of many of the nearby towers. Their purpose is to deflect the wind.

The City of Toronto adopted a Tall Building Design Guideline  in May, 2013. Section 4.3 of the 92 page document is dedicated to mitigating wind, but adherence isn’t enforceable.

“The way the system works today, the architectural team and developer, hires a consultant to undertake a wind study, and in the context of that study, indicated that the condition would be comfortable, but clearly it’s not.”

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