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WATERLOO REGION — The only thing rising faster than condos in a building boom are record high temperatures in the climate crisis.

The glass-walled towers need more energy for winter heating and summer air conditioning, and that increases carbon emissions, said John Straube, who teaches at the University of Waterloo school of architecture and is a leading expert on building exteriors.

“You can make anything work with enough heating energy and cooling energy — and we do,” said Straube. “But because of the carbon imperative, just because you can do it doesn’t mean you should do it. And increasingly we are being told we should not be allowed to do it.”

What is known as “window wall” became widely used during the past 20 years in condo tower construction. It started in Vancouver in the 1990s with the condo boom in that city’s False Creek neighbourhood.

Containing double-glazed glass inside frames custom-manufactured for each new building, the “integrated glazing units” are lifted into place and sealed. The window rises from floor to ceiling and was quickly dubbed “window wall.”

Window wall buildings look great in marketing brochures but they are coming under increasing scrutiny in a world that is looking for ways to reduce carbon emissions and avoid the very worst of the extreme weather caused by climate change.

“They are about one-third the efficiency of a typical single-family home built to code in Ontario right now,” said Straube. “It might be a quarter — it is a big deal.”

With deep expertise in civil, environmental, architectural, construction engineering, Straube travels the world researching building exteriors, publishes research papers and oversees his consulting firm. That’s in addition to his teaching at the school of architecture in Galt.

During the past 10 years the Ontario Building Code was amended and the window-to-wall ratio was limited to no more than 40 per cent. But that leaves enough design room to see large parts of towers dominated by windows.

Straube wants building officials to demand the use of more energy-efficient exteriors — what he calls the “skins” — on new condo buildings.

“And not just giving them a get-out-of-jail free card and doing weird trade-offs. No, no, the skin’s got to be good, and then we will work on other parts of the building,” said Straube. “And that is something locally we could demand.”

The challenge and the solution are found in a single building called One Victoria. The bottom part, the podium, is covered in pre-cast concrete.

“The lower part of that building is an example of what you can do for the future,” said Straube. “It is not hard to imagine what buildings look like that meet that carbon imperative, and the funny thing is, it is not a cost thing — it is not that they cost more, really.”

Thin slices of bricks were added to the front of the slabs during the manufacturing of the pre-cast exteriors for One Victoria. The street-facing walls of that podium look like brick, and change colour in the sunlight. Windows were punched into the concrete slabs.

That exterior covers a parking garage, but Straube said it is a better way to clad condos and meet the demand for multi-residential housing, reduce carbon emissions and achieve the density targets demanded by anti-sprawl legislation. Building heights should be limited to five floors.

“We can easily make buildings for less and perform at least twice as effectively thermally,” said Straube. “We just choose not to, because it doesn’t meet the style we are looking for.”

Some of the world’s great cities where he’s worked — Paris, London, Stockholm — achieved greater population densities and lower carbon emissions with concrete buildings, fewer windows and lower buildings.

“It means you have to make these choices in North America between a 30-storey tower or sprawl, which is a completely artificial choice,” said Straube.

“I don’t think we have explored these options that have historically been much more prudent solutions, which are four, five, six storeys built right up to a wide sidewalk, where people on the top floor can still shout down to people on the street to stay in contact with the street,” said Straube.

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