Building Decarbonization: A California Climate Imperative

The staff at the California Air Resources Board (CARB) is asking for help.¹ They are under a legislative mandate² to reduce the carbon intensity of building materials in California by 40 percent by 2035, and they are not sure how to do that. Truth be told, it may be that no one does, at least yet. While building decarbonization has long been recognized as a core imperative in California's comprehensive climate strategy, the core of this effort – embodied carbon – is a relatively new concept. So new, in fact, that it is never even mentioned in California's climate "Bible," the Scoping Plan that underwent its most comprehensive update and revision in 2022.³

Stepping back, California's climate strategy is economy-wide. CARB has identified major greenhouse gas (GhG) emission sources by economic sector and allocated a percentage of the existing emissions load to each. According to the Scoping Plan, the top emissions sector is transportation at 40 percent,