Environmental assessment of office buildings

Buildings have a significant impact on the environment, but just how big has still not been researched to the fullest extent. Benchmarking existing estimates for the whole building sector is difficult because the corresponding studies are poorly documented, and use different assessment frameworks and definitions for what the building sector encompasses. There are several tools to assess the impact of single buildings, but most come short in measuring the total magnitude by disregarding some of the life-cycle phases and the impacts of the supply chains. This research developed a user-friendly hybrid life-cycle assessment (LCA) tool for office buildings (BuiLCA) that can be used to assess the environmental effects of all life-cycle phases and the environmental consequences of decisions made over the life-cycle of the building. In particular, this tool includes a new methodology to assess the end-of-life (EOL) impacts of construction materials. This methodology was applied to concrete and shows that increasing the current recycling rate of concrete from 27% to 50% could yield a 2-3% (2. 7-5. 6 million metric tons of CO2 equivalent) reduction in the contribution of concrete in buildings to global warming potential (GWP), or the equivalent of removing approximately 612,000 cars from U.S. roads annually. The usability of BuiLCA is demonstrated through a case study of the CITRIS building on the UC Berkeley campus. By scaling up the full life-1 cycle impact of a single building to the country level, it is shown that U.S. office buildings alone represent 2% of the total U.S. energy use, while the whole building sector represents 40-50% of the same (previous estimates range from 30 to 40%). The overall impact of the building sector is also quantified for other environmental effects and global warming potential. It is estimated that close to 50% of SO2 emissions, and one-third of the country's GWP, and NOx and CO2 emissions come from the building sector. Overall, this research allows for comparing the relative magnitude of the impact of each life-cycle phase, and shows that the operational phase is not the only one with a significant environmental burden. For example, the materials acquisition and production phase and the operational phase are each responsible for about 40% of CO emissions. Over one-third of life-cycle PM10 is emitted during the materials acquisition and production phase. The results obtained in this research can be used to support better environmental decision making by building and construction industry stakeholders.