A Hybrid Method for Assessing Embodied Carbon Impacts of Post-Disaster Building Repair and Functional Loss

The building industry requires assessing embodied carbon from post-disaster recovery to improve international economic competitiveness. However, a standardized approach is not yet available for building assessment and design. The FEMA P58-4 methodology, which represents the current state of practice for assessing building damage and repair following earthquakes, has several limitations that may affect its ability to accurately estimate carbon emissions. This study proposes a hybrid method that combines unit process analysis (a detailed accounting of repair actions) with economic input-output analysis (industry-average estimates based on repair costs) to quantify carbon emissions from building component repairs and loss of building functions due to earthquake damage. The hybrid method considers various factors, including repair materials, material transport, construction equipment, labor travel, debris disposal, and occupant displacement. Additionally, the hybrid method accounts for the shortened useful life of buildings due to collapse or irreparable damage (requiring demolition and reconstruction), as well as future changes in construction and repair practices. A case study is presented to demonstrate the advantages of the hybrid method over the input-output method adopted by the mentioned methodology. The case study building reflects current code requirements in California with a low-to-moderate likelihood of severe damage due to seismic hazards during the design life. Nevertheless, the result reveals a high potential for carbon emissions from post-disaster building recovery, although this result varies depending on the assumed repair activities, transportation distances, and future scenarios.