Lawrence Berkeley National Laboratory

Structural materials in commercial buildings in the United States account for a significant fraction of national energy use, resource consumption, and greenhouse gas (GHG) emissions. Robust decisions for balancing and minimizing these various environmental effects require that structural materials selections follow a life-cycle, systems modeling approach. This report provides a concise overview of the development and use of a new life-cycle assessment (LCA) model for structural materials in U.S. commercial buildings?the Berkeley Lab Building Materials Pathways (B-PATH) model. B-PATH aims to enhance environmental decision-making in the commercial building LCA, design, and planning communities through the following key features: (1) Modeling of discrete technology options in the production, transportation, construction, and end of life processes associated U.S. structural building materials; (2) Modeling of energy supply options for electricity provision and directly combusted fuels across the building life cycle; (3) Comprehensiveness of relevant building mass and energy flows and environmental indicators; (4) Ability to estimate modeling uncertainties through easy creation of different life-cycle technology and energy supply pathways for structural materials; and (5) Encapsulation of the above features in a transparent public use model. The report summarizes literature review findings, methods development, model use, and recommendations for future work in the area of LCA for commercial buildings.