Toronto lakefront skyline. Credit: Chensiyuan; Wikipedia.
I wasn’t aware that Toronto has more glass condominium high-rise structures than any other city in North America, but I will take the Canadian Broadcasting Company’s word for it. According to a new three-part series by the CBC that started Monday, “Many of the glass condominium towers filling up the Toronto skyline will fail 15 to 25 years after they’re built, perhaps even earlier, and will need retrofits costing millions of dollars, say some industry experts.”
If the CBC series is correct, the problem may be growing because 130 new towers are under construction.
Certainly, window-walled buildings are popular, especially where there are great vistas, such as around the harbor in Vancouver. Glass is strong and often less expensive in construction products than stone, brick or concrete. And glassmakers have been attempting to introduce more energy-efficient products.
However, the performance, energy efficiency and designs incorporating glass walls lead, according the CBC to “slow-motion failure” and the equivalent of “throw-away buildings” whose maintenance costs are predicted to soar in a decade or two. The CBC also cites the Ontario Building Code as being a problem, although I don’t know how the OBC compares to other cities.
With stories like this, it is always hard to separate out who “owns” these types of problems. Glassmakers? Construction engineers? Building designers? Developers?
The CBC makes use of interviews with John Straube, a professor at the University of Waterloo who wrote a 2008 paper (pdf), “Can Highly Glazed Building Façades Be Green?,” which addresses some of these issues and he seems to argue that the problem mainly is not with glassmakers, whom he acknowledges as working to develop and offer “super window” and phase-change products. Instead, Straube argues in the paper that the problem is with excessive glazing area and he writes
“Many designers have shown that beautiful and high-performance buildings can result from a proper balance of glazing quantity and quality. All too often, however, designers appear to choose all-glass curtain walls or floor-to-ceiling strip windows because they make it easy to create a sleek impression while leaving all the tricky details in the hands of the manufacturers. How much longer can we afford to pay the energy bills that result from that choice? It’s high time to revive the craft of designing beautiful facades that don’t cost the earth.”
Straube, also described by the CBC as a building science consultant, tells the broadcaster, “We have a hard time thinking [ahead] 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.”
Straube goes on to warn, “Now is about when we should start seeing trouble with 1990s buildings, with the glass starting to get fogged up, the rubber gaskets and sealants starting to fail.”
Here are the currently available links to the series (I’ve been experiencing some performance issues with these, so be patient):