Investigation of occupant-related energy aspects of the National Building Code of Canada: Energy use impact and potential least-cost code-compliant upgrades

Following our previous study, which indicated that several occupant-related assumptions in the National Building Code (NBC) of Canada are different from findings in recent measurement-based studies, this study aims to: i) quantify the direct energy impact associated with discrepancies between the current code's occupant-related assumptions and those obtained from recent measurement-based studies and ii) demonstrate how key NBC requirements could be reevaluated as a result of the new/proposed occupant-related assumptions. In this regard, this paper applies energy modeling and life cycle costing (LCC) to 11 representative archetypes across different Canadian climate zones. First, EnergyPlus simulations were conducted to evaluate the energy impact of the proposed and existing occupant-related assumptions. Second, LCC was used to evaluate code requirements' economic implications under these two sets of occupant assumptions. Our results indicate that the default occupant-related assumptions used by NBC generally lead to higher predicted heating, but lower cooling, energy consumption. However, heating energy is more significant since heating energy use is typically an order of magnitude higher than cooling energy use for Canadian homes. Our analysis also indicates that the current occupant-related NBC assumptions yield different optimal potential code-compliant upgrades in some cases relative to the new energy-related occupant assumptions.

Automated summary

The study found discrepancies between occupant-related assumptions in the National Building Code of Canada and recent measurement-based studies, resulting in potential increase in heating energy consumption but decrease in cooling energy consumption. Heating energy consumption is more significant, and current occupant-related NBC assumptions may yield different optimal upgrades in certain cases compared to new energy-related occupant assumptions.