Leveraging hourly emission factors of electric grids to evaluate the operational performance of Canadian buildings

Building electrification is seen as an essential means towards decarbonization, yet greenhouse gas emissions (GHG) due to building electricity use vary significantly depending on grid energy generation mixes. While total energy usage is still a primary concern, the timing of energy use becomes increasingly critical in terms of flexibility, energy costs and GHG emissions. This paper investigates how hourly average and marginal emission factors of different electric grids could impact the assessment of building GHG emissions. The proposed case study targets medium-office buildings located in two Canadian provinces (Québec, Ontario), equipped with a dual energy heating system and leveraging fuel switching during electric grid peak events to increase flexibility. Results show that calculations using average and marginal factors could lead to 44-106% differences, while in Ontario, fuel switching leads to an increase in GHG emissions using average factors but a decrease using marginal factors. These results laid the foundations for a broader discussion on appropriate metrics to assess building performance to properly drive building decarbonization strategies or policy.