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Additional Contributors: Katie Ackerly – David Baker Architects, Meg Duff – AEA, GG Merkel – AEA, John Neal – AEA, Andrew Brooks – AEA, Tammy Siliznoff – RDH Building Science, Michael Hsueh – RDH Building Science, Curtis Harrington – UC Davis Western Cooling Efficiency Center
Buildings account for nearly a quarter of planet-heating pollution in California and are key to achieving the state’s climate and clean energy targets. At the same time, low-income residents face disproportionate energy costs, with energy spending up to three times higher than non-low-income households.
Through REALIZE-CA, RMI developed high-impact retrofit packages to overcome the unique challenges of California multifamily housing and significantly lower energy usage and costs. This guide, produced by RMI, Association for Energy Affordability, Inc., Integral Group, David Baker Architects, and University of California, Davis outlines a recommended retrofit package for existing multifamily buildings in California, drawing on insights from pilot demonstrations funded by the California Energy Commission’s EPIC program.
The retrofit guide features detailed design and installation guidelines that integrate innovative building technologies that reduce energy demand and effectively pair with renewable energy generation such as solar. The guide also provides financing recommendations on how to leverage incentives from the federal Inflation Reduction Act and offers solutions for gap financing to support affordable multifamily housing projects.
REALIZE-CA Retrofit Package Measures

Acknowledgements:
RMI would like to thank the California Energy Commission (CEC) for its unwavering support and guidance throughout the REALIZE-CA program. Together, we retrofitted over 300,000 square feet of multifamily affordable housing throughout California, developing a standardized approach to scaling building decarbonization and improving the lives of low-income ratepayers statewide.
In addition, RMI would like to thank the tenants and building owners at each pilot demonstration for their trust and patience during the program. Pilot demonstrations present unique challenges, and without commitment from each community our work would not have been possible.
And last but certainly not least, RMI would like to thank our wonderful project partners for their invaluable contributions and perseverance over the years:
- Association for Energy Affordability
- David Baker Architects
- RDH Building Science
- UC Davis — Western Cooling Efficiency Center
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