The City of Nelson is undertaking a research project into one of the most problematic aspects of climate change.
The city’s building inspector, Sam Ellison, is searching for a way to account for embodied carbon in the city’s calculation of the carbon footprint of its new buildings.
Embodied carbon is the footprint of the building materials themselves, such as concrete, styrofoam and steel – the carbon released to the atmosphere through their manufacture and transport before they even become part of a new Nelson house.
Ellison says the BC Energy Step Code is a step in the right direction but doesn’t take embodied carbon into account.
The Step Code calculates the heat loss from new buildings, and through increasingly advanced ways of constructing the building envelope, it attempts to reduce that loss and reduce energy use.
“But if we’re not careful about the choices we make on the building materials,” Ellison says, “we can get a very energy efficient building that actually has a total carbon contribution that’s as bad or worse than if we had made it less energy efficient.”
Ellison says the provincial government is aware of this and decided to get the Step Code established before taking on the more complex problem of embodied carbon.
Now the City of Nelson is looking into embodied carbon on its own, independent of the province. But Ellison wants to make it clear that the city won’t be dictating anything to builders about construction materials, because municipalities can not legally change building code requirements without asking the province.
“This is not something we are going to make builders do,” he says, adding that eventually the city may create incentives for builders to reduce the embodied carbon in their buildings, without hard and fast rules.
But the city has decided to collect some local data, to inform its plans for the future.
Using several Nelson houses already built to th Step Code, the city will calculate the carbon footprints of those houses including embodied carbon, and then calculate what the footprint would have been if different materials had been used.
This technical work will be done by consultant Michèle Deluca of 3West Building Energy Consultants, using a calculator developed by Builders for Climate Action in Ontario.
“First you put in the area for all the different components of the building, how many square feet of exterior walls, foundation, that kind of thing,” Deluca told the Nelson Star. “Then it will basically tell me an overall embodied carbon intensity for that building.”
The calculator contains product declarations that show the carbon footprint of a variety of materials.
“We could show a house that’s built with spray foam and lots of concrete,” she said. “And then we could show, just by changing the tab to different materials, what would have happened if that house had been built with, say, stick frame and cellulose insulation.”
Ellison says Deluca’s company is not the only partner in this project.
A group of mature students with business backgrounds in the BCIT Sustainable Business Leadership program have taken on four projects for this year, one of them being Nelson’s exploration of embodied carbon.
”They’re going to try to turn it into a program that Nelson could roll out,” Ellison says.
Also, Alex Leffelaar, a student of environmental science at BCIT and a member of Nelson’s Youth Climate Corps, has been conducting research on embodied carbon for the city as a student project.