UC Davis

Greenhouse gas (GHG) emissions from the building sector in 2021 contributed 36% of overall US carbon dioxide (CO₂)­ emissions according to Energy Information Administration (EIA 2021). The space heating of buildings, a large part of the overall emissions, relies heavily on natural gas. Electrification with a heat pump eliminates onsite emissions from space heating but results in indirect emissions from the electric grid. The generation mix of the electric grid evolves over time and varies widely by geographic location. This study presents a temporal and spatial distribution of the impacts of electrification of space heating in residential and office buildings. A comprehensive analysis was conducted to compare modeled GHG emissions over the operational life of a heat pump and a gas furnace installed between years 2022-2036 in six regions across the US. A residential home and a three-story medium office building were considered in this study and Energy Plus prototype models were used to simulate the energy use for space heating in 99 locations across the continental US. GHG impact calculations accounted for long-run marginal emissions from electricity generation from 2022 to 2050, emissions from natural gas combustion, and emissions from leakage of methane and refrigerant. The population weighted average results in the US for the residential home show a 30 - 68% reduction in 100-Year global warming potential (GWP) emissions for a heat pump over a gas furnace, with savings increasing as the year of the installation is deferred (2022-2036). Similarly, for the medium office building, the emissions change ranged from a 1% increase to 51% reduction. Office buildings show lower GHG emission savings in the initial years because of increase in refrigerant charge from the installation of a heat pump and reliance on electric-reheat in the variable air-volume boxes.