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The Engineer: We need better glass facades

The writing on the (glass) wall

July 30, 2019  By David Heska P.Eng.

When the mayor of New York City commemorated Earth Day in April stating that he would “introduce legislation to ban the glass and steel skyscrapers that have contributed so much to global warming,” many in our industry took note.

Did the mayor actually mean that he would ban glass or was this another classic example of hyperbole? Three months later we are all still here, buildings continue to be constructed in New York City with glass, and the sky has not fallen. However, the intention of the mayor’s statement is clear: we need to build better buildings.  

Closer to home our provincial governments have been taking steps to improve our building stock. B.C. seems to always be a few steps ahead with Ontario typically following along after. Some of our readers may be aware that the July 1 deadline for buildings in Ontario to report on their 2018 energy use has come and gone. All commercial, industrial and multi-unit residential building owners are now required to report the equivalent electricity and natural gas usage of their buildings per gross floor area. For this year’s deadline, any building greater than 100,000 square feet was required to submit, but next year the threshold drops to any building greater than 50,000 square feet. So what does this have to do with the glass industry? This background information goes to show that the push for better-performing window wall and curtainwall systems with lower U-values is not going away. It is going to increase.  

To be honest, I’m happy we are getting serious about improving the performance of our buildings. In 2009. Natural Resources Canada released a report outlining the energy use intensity of Canadian buildings. Those constructed between 1920 and 1999 generally had an energy use intensity of around 300 equivalent kilowatt hours per meter squared. But after the year 2000, guess what happened? The energy use intensity of buildings jumped to over 350 ekWh/m2. I won’t join the New York mayor in blaming the glass and steel industries (since we were simply responding to the market trends). If clients and architects are asking for more glass, then we can give them more glass. But the question now becomes what will be done going forward. The IGMA Emerging Technologies Committee provided a good report at the recent conference in British Columbia highlighting some trends. The solution will not be easy. It will require innovation and investments, and mistakes will be made along the way. But we need to figure out how to reduce air leakage through our window wall and curtainwall assemblies. We need to continue to improve the thermal performance of these systems at the mullions and at the centre of glass. Partnerships and collaborative testing between companies needs to increase along with engagement with our post-secondary institutions.  


The next-wave energy use intensity data should made public in the next few months. But until then let’s roll up our sleeves, innovate and improve our built environment with glass that’s durable and efficient!

David Heska, P.Eng. is a director with WSP’s building sciences team in southwestern Ontario. He oversees the operation of the Hamilton, Kitchener and Windsor offices. David has been involved on window simulation projects as well as the design and replacement of windows in commercial and residential buildings. He can be reached at

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