Achieving ambitious decarbonization targets will require the construction industry to accelerate deep carbon retrofits on the existing building stock across Canada.
“Here in B.C., the overwhelming majority of the carbon emissions from new buildings are directly linked to materials and construction,” said Aaron Knorr, senior associate with Perkins & Will at the Canada Green Building Council’s (CAGBC) Building Lasting Change conference.
“Retaining and improving existing buildings that we have really has to be a critical part of our strategy for decarbonizing our industry.”
A recent project the firm worked on involved a 1940s concrete warehouse in Vancouver that had an owner mandate to prioritize carbon reduction along with achieving CAGBC’s Zero Carbon Building standard certification.
Knorr explained that Perkins & Will prepares a lifecycle assessment on every project to come to a decision about whether to reuse an existing building or to undertake the more conventional approach of a teardown and rebuild.
“We were able to realize a significant potential carbon impact for the project just through this fundamental decision of preserving the building and the existing structure at the outset,” he said.
Material selection was a critical focus on this project with mass timber used to add four new storeys on top of the existing structure and specification of low carbon concrete and XPS insulation.
Through the firm’s reuse, reduce and specify strategy, the overall embodied carbon for the project sits at 339 kg CO2e/m2 (below CAGBC’s embodied carbon innovation credit of 350 kg CO2e/m2), which “represents a significant achievement,” said Knorr.
He stressed meaningful carbon reduction requires commitment and collaboration. “Achieving low carbon buildings really requires a collaborative approach and buy in from everyone on the project team from project kick off to project completion.”
“Finally, designing for low carbon requires a holistic approach to design. We need to build literacy and fluency with an understanding that the carbon impacts of design decisions we make into every aspect of our design,” he said, adding conversations with clients, trades, consultants are needed to move the industry forward towards low carbon solutions.
Collaboration was also cited by Stephen Montgomery, sustainability specialist at PCL Constructors, as being key to reaching decarbonization goals.
“We need to find a way to put design, construction and operation silos together and find out how we’re going to make this work,” he said. “We need to infuse these carbon roadmaps with actionable budgets, schedule and logistical insights.”
He cited that the International Energy Agency monitors clean energy progress and the agency has described the building sector as “not on track” for reaching the 2050 climate targets. New green building construction alone won’t reach Canada’s 2030 greenhouse gas reduction targets.
“We have to decarbonize Canada’s 482,000 commercial and public buildings by 2050,” said Montgomery. The buildings also need ongoing net zero operation with a shrinking workforce. “We’re handing over a more complex product to a shrinking industry of labour – a 30 per cent reduction in trained building operators.”
Low-rise multi-unit residential buildings and offices represent the largest building stock available for green retrofits. The CAGBC estimates large building retrofits could potentially reduce building-sector emissions by 51 per cent (21.2 million tonnes of CO2e).
“No one has a magic method but it’s time to get started – to push some of these first projects over the starting line” said Montgomery.
Cheryl Mah is managing editor of Construction Business.
