The slow-motion failure of Toronto's glass condos
Photo illustration: Dwight Friesen/CBC
Over the past decade, Toronto's building boom has been dominated by tall glass condo towers.
They've transformed the look of city skylines all over the world – especially here in Toronto, where according to Emporis.com we've built more towers per capita than any other city in North America. But it may be a trend that puts style over substance.
A small but growing chorus is sounding the alarm about the future of these buildings.
Building scientists have known for a long time that glass-walled structures are less energy efficient than the stone and concrete buildings that were put up forty of fifty years ago. But the market demand for glass combined with the relatively low cost of glass-wall construction means the building industry has been happy to oblige.
However, industry insiders warn that as energy costs climb, glass towers may become the "pariah" buildings of the future. In these stories, we explore the hidden costs of building with glass and
the slow-motion failure of window walls.
We also look at why the Ontario Building Code failed to make energy performance a priority, and meet a developer who is reconsidering the construction of such buildings.
Building science consultant and University of Waterloo professor John Straube wrote a paper called Can Highly Glazed Building Facades be Green? View Paper [1MB .pdf]
John Straube, a building science consultant and professor in the Department of Civil Engineering and School of Architecture at the University of Waterloo says glass condos are a "perfect reflection" of a society that's found it easier to throw things away than to build them to last.
"We have a hard time," says Straube, "thinking five years when we buy a laptop, ten years when we buy a car. With these buildings – both the skin and the mechanical systems are going to have to be redone in a 25-year time frame. The concrete structure will be there a long time but in 20, 25 years time, we are going to see a lot of scaffolding on the outside of the buildings as we replace the glazing, sealants and the glass itself."
Although falling glass from the condo balconies has attracted most of the public attention during the summer of 2011, building scientists warn that the long-term failure of the glass structures – although less sensational – is much more serious.
Most of them are built using window-wall systems which have next to no insulation value, except for a half inch of heavy gas between the two panels of glass.
As John Straube points out, what glass does really well is conduct heat. "A little experiment anyone can do at home is get a glass for drinking. Pour boiling water into it, and try and pick it up. You'll burn yourself."
Straube, along with building science colleagues like Ted Kesik at the John H. Daniels Faculty of Architecture at the University of Toronto, warns that as energy costs climb, the costs of heating and cooling glass towers will increase the monthly fees.
Kesik wrote a paper called The Glass Condo Conundrum (250KB .pdf) on the potential liabilities of glass towers.
The Glass Condo Conundrum
It's not just the energy costs. Glass structures require major maintenance much earlier in their life cycle than a traditional structure made of precast or brick.
A longer-lasting and more energy-efficient solution: masonry block behind a brick facade. Punched windows are used instead of windows from floor to ceiling. (Ted Kesik)
Straube warns maintenance costs will skyrocket in 20 to 25 years' time as the buildings age. The windows will begin to fog up, and the cost of replacing entire walls of glass will be prohibitive on highrise structures that can only be accessed from swing stages.
Building scientists talk about the life cycle of a building, akin to a human life cycle, language that encourages people like Straube to see a building as an organism. "It has lungs," says Straube, "it has veins, all of that stuff – it has a structural skeleton."
To Straube, a building is a living, breathing thing, enclosing the people who live inside. Building with glass walls is to miss the main point of a building, says Straube – sacrificing the protection that is a building's first duty for a beauty that is only skin-deep.
"It's almost derogatory in my world," says Straube, "to forget about everything else that's part of experiencing a building. I like to think what is this building going to be like on a dark and stormy night. In our climate particularly, we care about that. It's life and death."
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