Electrification of buildings is emerging as the new front in the fight against global warming, and in that effort, apartment buildings could take a leading role.

A new report focuses on the potential for significant reduction in greenhouse gas emissions specifically from multifamily buildings that convert their water-heating systems from gas to electric.

"Increasing Sustainability of Multifamily Buildings with Heat Pump Water Heaters" analyzes the economics and potential benefits of replacing fossil fuel water heaters with heat pump water heaters in multifamily buildings. Authored by the American Council for an Energy-Efficient Economy, Washington, D.C., and the New Buildings Institute, Portland, Ore., the study was published Nov. 18, 2021.

The report finds that retrofits could save up to 175 trillion Btus per year, eliminate 6.5 million metric tons of greenhouse gas emissions, and provide 3.5 terawatt-hours of potential load-shifting benefits to the electric grid.

The report cites statistics from the U.S. Energy Information Agency that show water heating in multifamily buildings with five or more units uses more energy than other utilities, including space heating, cooling and lighting. This higher level of energy use means the potential for energy savings is also greater.

According to the report, converting gas-fired water heaters to the most efficient technology in electric heat pump water heaters (HPWHs) could cut the greenhouse gas emissions from this equipment by an average of 58%. Furthermore, if the technology is powered entirely by clean sources, emissions drop to zero.

Despite the potential, the report also notes that cost is a prohibiting factor. To overcome this obstacle, the writers suggest that policymakers offer incentives to building owners to invest in retrofits. The study recommends federal, regional and utility financial incentives, plus policy changes to support the adoption of HPWHs in multifamily buildings.