A hybrid life cycle assessment model for construction processes

This research qualitatively and quantitatively examined the environmental impacts due to the construction phase of commercial buildings. Previous building research often overlooked the construction phase and focused on the material and use phases, discounting the significant environmental impacts due to construction. The research was conducted using life cycle assessment (LCA) methodology, which is a systematic environmental management tool that analyzes and assesses holistically the environmental impacts of a product or process. This research contributed to further developing LCA research by focusing efforts on hybrid LCA modeling. The context of this research was established through examining green building rating systems, policy review, and project delivery methods with respect to the modeled results. Documented life cycle inventory results focused on PM emissions, GWP, SOx, NOx, CO, Pb, non-methane VOCs, energy usage, and solid and liquid wastes. Results compared with the entire building life cycle indicated that construction, while not as significant as the use phase, is as important as the other life cycle stages. In terms of hybrid LCA modeling, the augmented process based LCA proved to be effective in modeling the construction phase and allowed for efficiently combining process and input-output inventories. Including input-output results, especially construction service sectors, is critical in construction LCA modeling. One case study’s results demonstrated that services had the highest level of methane emissions and were a significant contributor to CO2 emissions. Recommendations are made in terms of green building rating systems and national policies, including placing higher significance on construction activities within the United States Green Building Council’s Leadership in Energy and Environmental Design (LEED) green building rating system.