Energy Efficiency in Existing Buildings

California has long been a leader in efforts to improve building energy efficiency, both at the time of construction and upon a major remodel or equipment replacement.

The first Energy Efficiency Action Plan was required by California Assembly Bill 758 in 2015. The 2021 Energy Efficiency Action Plan, the most recent version, was covered in two documents, 1) The 2021 California Building Decarbonization Assessment, and 2) The final 2021 Integrated Energy Policy Report Volume I Building Decarbonization.

Since then, building energy efficiency and decarbonization have assumed a more prominent role in efforts to cost-effectively reduce greenhouse gas emissions, improve public health, and address longstanding energy equity concerns. The 2025 Building Energy Action Plan will be published in late 2025. The report will identify challenges and make recommendations to legislators, advocates, researchers, the Department of Energy, and other stakeholders about what’s needed to move existing building energy efficiency and decarbonization forward in California.