Decarbonizing Space Heating in Existing Centrally Heated Multifamily Buildings

Large multifamily buildings with central heating systems that burn fossil fuels are among the hardest to decarbonize, but new systems such as window-mounted heat pumps, central air-to-water heat pumps, and “mono-block” mini heat pumps provide new options for decarbonizing these buildings. This report finds that window heat pumps generally have the lowest life-cycle capital and energy costs compared to various decarbonization options.