Lawrence Berkeley National Laboratory

Decarbonization technologies are becoming easier to implement and more cost-effective in new multifamily housing, but retrofitting costs remain a significant challenge. Energy retrofits are crucial for prioritizing low- and moderate-income communities already burdened by energy, environment, and health issues. Cost and split incentives are the main barrier hindering the scalability of home decarbonization in affordable multifamily housing, creating unique challenges and opportunities for homeowners and renters. Therefore, understanding and addressing cost barriers is important for a fair energy transition. We lack essential data on the costs of affordable multifamily electrification solutions and technologies. Such data is essential for effective planning/policy activities, implementation of home decarbonization efforts, and guiding R&D aimed at reducing retrofit costs. To address these issues, we compiled information from 3,208 multifamily energy upgrade projects covering 14 US states, encompassing a total of 7,126 individual retrofit measures. Our findings summarize electrification technologies and associated decarbonization measures in current practice. We also examined cost data to identify key factors influencing both project measures and overall project costs. Some key results are that in high-rise buildings, the impact of the cost per unit is more significant when retrofitting the building envelope compared to low-rise buildings, however; the cost per unit for HVAC installation remains relatively consistent across all multifamily building types. Also, rural areas have higher retrofit costs, even when considering factors like DACs status.