Carlisle, S., Waldman, B., DeRousseau, M., Miller, L., Ciavola, B., Lewis, M., and Simonen, K. (2022). Buy Clean California Limits: A Proposed Methodology for Setting Industry-Average GWP Limits for Steel, Mineral Wool, and Flat Glass. Carbon Leadership Forum, University of Washington. Seattle, WA. https://hdl.handle.net/1773/48600
Abstract
The Buy Clean California Act requires the California Department of General Services (DGS), in consultation with the California Air Resources Board, to establish maximum acceptable global warming potential (GWP) limits at industry-average for structural steel (hot-rolled sections, hollow structural sections, and plate), concrete reinforcing steel, flat glass, and mineral wool board insulation (heavy and light). DGS is directed to set these limits at the industry average using data from facility-specific environmental product declarations (EPDs) or industry-wide EPDs based on domestic production data.
In order for GWP limits to be effective they must be scientifically derived, transparent in their underlying methodology, and clear in scope and definition. Calculating industry-average values using EPDs, as required by the BCCA, is challenging: the quality and quantity of data available for calculating GWP limits varies by product type and is continually growing.