Codes and standards
NRC proposing adding embodied carbon to code
February 6, 2023 By Patrick Flannery
The Canadian Board for Harmonized Construction Codes has released a set of draft proposals that would see future editions of the National Building Code and the National Energy Code of Canada for Buildings include requirements limiting the greenhouse gases emitted by providing power and heat to the building, and limiting the greenhouse gases emitted as a matter of embodied carbon in the manufacture, transportation, maintenance and disposal of its building materials. The draft proposes to include operational emissions limits in the 2025 code update and embodied emissions limits in the 2030 update.
The proposed limits would represent an expansion in scope for the NBC’s and NECB’s environmental regulations, which presently only govern the amount of energy a building requires in its operation without regard for the source of that energy. Under the draft proposals, new requirements would consider the energy source the building uses and also the ultimate source of its electrical energy. That could mean buildings in regions with less-emitting energy supplies (hydroelectric, nuclear, solar, wind) could have different requirements from buildings in areas that burn fossil fuels for electricity generation.
Including embodied carbon in the building’s compliance path would represent another major addition to the requirements it has to meet and another significant shift in the compliance requirements themselves. It is possible that present energy-efficient designs would not prove as desirable as less-efficient designs when the embodied carbon of their materials is taken into account.
The draft proposals also set out some general options for metrics that could be used to measure these factors. The CBHCC will be collecting input on whether to use a reference metric that measures performance versus a reference building; an intensity metric that measures emissions per square meter; or an absolute metric that measures emissions per building. That last one raises the interesting possibility of an architect simply reducing a building’s size in order to hit its emissions targets.
The first round of consultations is now open and closes March 30. Comments on the draft proposals can be emailed to CBHCCSecretary-SecretaireCCHCC@nrc-cnrc.gc.ca.
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