More ice risk seen from new building towers

Energy-efficient buildings come at a cost to those walking below, warns consultant’s new report.

In March 2008, icicles, measuring 30 to 50 cms in length, formed on The Crystal at the Royal Ontario Museum.
In March 2008, icicles, measuring 30 to 50 cms in length, formed on The Crystal at the Royal Ontario Museum.   (TONY BOCK / TORONTO STAR) | Order this photo  

The ability of Toronto’s new energy-efficient towers to contain heat has a dangerous downside: their exteriors can get so cold that ice and snow build up and eventually crash to the ground.

Signs downtown warning pedestrians of falling ice or areas cordoned off to protect passersby are bound to become more common, warns ice and snow consultant Roman Stangl.

“It’s something we should be concerned about and it is a problem that we’re hearing more and more of with these energy-efficient buildings,” said Stangl of the Cambridge, Ont., firm Northern Microclimate which works with building designers, developers and property managers to mitigate risks.

Energy-efficient glass, new building materials and uniquely angled architectural designs contribute to an increase in the frequency and severity of falling ice, he said.

“Some façades literally promote hazardous ice formation,” Stangl and a co-author wrote in a 2012 report, “Increasing Problems of Falling Ice and Snow on Modern Tall Buildings.” .

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The issue continues to make news. On Feb. 7, a man in his 30s suffered minor injuries when he was struck by ice falling from a building on St. Clair Ave. W., near Yonge St.

That day in New York City, chunks of ice crashed to the ground from atop One World Trade Center, the tallest building in the United States. A main exit from the PATH train terminal was closed and police cordoned off two blocks in lower Manhattan to protect pedestrians. That was just one of various incidents related to snow or ice on New York buildings in recent weeks.

One reason ice is falling from modern towers — or high-performance buildings — is because they’re energy efficient. Their double- or triple-pane windows reduce heat loss, so snow may accumulate on the glass, said Stangl. In older, less-efficient windows, enough heat escapes through the glass to melt the snow on contact.

Another popular tower feature, protruding sun shades, end up creating ledges for snow and ice to accumulate.

“And now we’re experimenting with a whole bunch of new materials that have not been evaluated with respect to snow and ice performance,” said Stangl, citing metals, high-performance coatings and man-made stone that haven’t been sufficiently tested for our harsh winters.

Problem issues should be identified during the design process where they can be more easily resolved, said Stangl. He is part of a group organized by ASTM International (formerly the American Society for Testing and Materials) to create standards for ice and snow on buildings and structures, which he hopes will be adopted by Canada and the United States.

Ontario’s Building Code, which sets out minimum requirements for construction of safe buildings, deals with issues such as wind and snow loads but doesn’t address falling, sliding or windblown ice, said Stangl.

Municipalities are responsible for enforcing the Building Code and can establish property standards, including maintenance requirements for existing buildings. The city could request developers do studies to identify problematic design features that encourage snow and ice formation, said Stangl.

He would like to see both the city and province address the issue, noting falling ice is a growing problem.

“We do hear about it a lot as a firm,” Stangl noted, adding such incidents aren’t typically publicized or dealt with industry-wide for fear of litigation.

Councillor Peter Milczyn, chair of the planning committee, said he is not sure how widespread the problem is in Toronto and is not aware of any city plans to address the issue.

“Certainly, if it is becoming an issue, the best way to deal with it is the (provincial) building code. But we could certainly also implement something through the tall building design guidelines, so we could have something that’s kind of Toronto-specific that we could try to require builders to adhere to.”

Milczyn noted the city sees plans “for some interesting roofs on condos, sloped roofs and so on, and invariably they get cut out because what happens is that will allow snow and ice to stop on the roof and then fall.”

Stangl won’t comment on specific downtown buildings, but falling ice has made headlines in recent years.

On Dec. 28, rising temperatures resulted in ice falling off various structures, prompting numerous calls to police. Icicles fell from several unfinished floors of the 78-storey Aura project, Canada’s tallest residential tower. A block of Yonge St., between Gerrard and College Sts., was closed off for 10 days as a result.

In March 2008, large icicles formed on the Royal Ontario Museum’s Michael Lee-Chin Crystal. And in March 2007, ice sheets fell from the CN Tower and forced the closure of the Gardiner Expressway.

In Toronto, it’s tough to ascertain just how big a danger dangling ice is because neither the city nor EMS keeps statistics.

Emergency Medical Services spokeswoman Kim McKinnon said the incident on St. Clair was the only one involving ice falling on a person that had come to her attention in the last three years.

Ann Borooah, chief building official for Toronto, said snow and ice falling from a building is “part of the architectural and engineering practice and not something we review against a standard.”

A city bylaw deals with snow and ice removal from the ground but not from actual buildings, said city spokesman Bruce Hawkins, adding “It is a property owner’s responsibility to keep their property safe” from this risk.

With files from Ira Lamcja and Daniel Dale