Canadians constructing North America's biggest green buildings
Concept design for new residence at the University of Toronto's Scarborough campus. Photo courtesy of Kearns Mancini Architects
Tenants this month will move into a six-story Vancouver apartment building designed to be so energy efficient, you could heat each bedroom with a 100-watt light bulb.
Boasting 85 studio, one- and two-bedroom units, The Heights will be the largest "passive house" building in Canada.
But it won't hold that distinction for long, reports CBC News. Others are under construction and many more are at the rezoning stage, including a residence that will house 750 students at the University of Toronto's Scarborough campus and two 40-plus highrise towers in Vancouver that aim to be the tallest passive house buildings in the world.
Passive houses are green buildings constructed using a set of international design principles and standards that allow them to use up to 90 percent less energy for heating and cooling than conventional buildings — and produce far fewer greenhouse gas emissions.
That's of interest to Canadian cities that want to meet greenhouse gas reduction targets and ultimately Canada's commitment to cutting its emissions to 30 percent below 2005 levels as one of the 197 countries that signed onto the 2015 Paris climate change accord.
According to the most recent report from the Intergovernmental Panel on Climate Change, buildings generate about 20 percent of global greenhouse gas emissions linked to human-caused climate change, and 47 percent of all indirect emissions from electricity and heat production.
In cities such as Toronto and Vancouver, buildings are the biggest generator of greenhouse gases, accounting for 53 and 56 percent, respectively, of municipal emissions in 2014. Both cities plan to eliminate greenhouse gas emissions from new buildings by 2030.
While most passive houses in Canada so far have been single-family homes, that's about to change.
'Not rocket science'
It's possible to scale passive house design up to much bigger buildings, say architects and builders who are doing that.
"It's not easy, but it's also not rocket science," says Scott Kennedy, principal of Cornerstone Architecture, which designed The Heights for Vancouver-based developer 8th Avenue.
Passive houses are called that because they're generally designed to stay at a comfortable temperature without "active" heating and cooling like furnaces and air conditioners.
To stay comfortably warm or cool, they rely on:
- Passive heat sources, such as the body heat of the occupants or the sun falling on their walls and windows.
- Heavy insulation.
- Ultra-efficient windows and doors.
- Mechanical ventilation systems that capture and release heat as needed from air entering and leaving the building.
The design also eliminates materials and structures that transfer heat between the interior and exterior of the building. For example, insulating fibreglass clips may replace heat-conducting metal screws in order to attach siding.
Comfort, fresh air
Kennedy says energy efficiency isn't the only benefit.
"The big story is you're living in a more comfortable building, you're living in a building without drafts," he said. "It'll survive a power outage without getting cold and it has fresh air in it 24 hours a day."
About 2,000 passive houses have been built across Canada so far, mostly in the past five years, says Passive House Canada, a non-profit group that educates builders and designers. Kennedy is on its board as its past chair.
'The heat is already inside'
New challenges arise when you scale up to even bigger buildings, like the University of Toronto's Scarborough residence.
"This would be one of the biggest in the world — definitely the biggest in North America right now," said Deborah Byrne, a passive house designer for Kearns Mancini Architects. Byrne and her firm conducted a recent study to show it's possible to design such a huge residence packed with students as a functioning passive house.
The design it came up with includes an eight-story tower and a 10-story tower, connected at the bottom by a black podium containing a huge dining hall and commercial kitchen, along with stores and student common areas.
The final design and build team will be chosen from a competition in January 2018. Construction will start in February and the first students are scheduled to move in in September 2020.
In the U of T residence, heat will be generated by 750 students, 750 bar fridges, hundreds of hot showers each morning and a commercial kitchen cooking about 1,000 meals three times a day, along with hundreds of appliances like computers, hair dryers and laundry machines.
The upside is that passive high-rises can be built anywhere, without worrying about their access to direct sun exposure, and don't need to be insulated as heavily as single-family homes.
But they're more of a challenge to cool. Byrne and her team have proposed cooling the U of T residence using a geothermal system.
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