California Air Resources Board

Thank you for giving PCI West and the Precast, Prestressed Concrete Industry an opportunity to present our comments. Please see attached file.

Slide 62, Request for Feedback, Question 2 Feedback on the method and approaches

• We understand that the USEEIO model:
o was chosen to establish a baseline in lieu of using EPDs due to lack of EPDs for all building products.
o may or may not be used for reporting and measuring progress toward the 40% net reduction in greenhouse gas emissions.
o allocates emissions to various industry sectors using economic data.
o uses TRACI 2.1 characterization factors.
• Comments:
o The USEEIO model can be used to determine the relative contributions of various industries to the overall GHG emission of the building sector for a given year.
o Knowing these relative contributions is helpful in setting priorities for reporting by industries.
o However, there are concerns about using the USEEIO model to determine California’s GHG emissions reductions.
o Best practice in GHG benchmarking necessitates that differences in modeling are minimized so that any differences in results can be attributed to real reductions in GHG emissions. As an example, Section 5.5 of ISO 21930 lists several items that must be considered when comparing environmental impact results.
o Because emissions attributed to sectors are allocated by costs, there are concerns that the different inflation rates for various materials will affect results.
o Current EPDs are beginning to calculate environmental impacts based on TRACI 2.2. However, it is important to report GHGs based on the same characterization factors as those in the EEIO model.
• Questions:
o How will CARB account for the changes in unit prices of goods that are not consistent across sectors?
o With updates to the background characterization factors, will the baseline USEEIO model be updated with updates to TRACI model to align with EPDs?