Whole Building Life Cycle Assessment of a Living Building

Abstract

A whole building life cycle assessment (LCA) was performed on a Living Building, focusing on impacts from green building materials, a decentralized water system, a net-positive use phase, and the end-of-life of structural materials. The material processes used in this LCA were adjusted from standard to green by removing the use of toxic chemicals; results show carcinogenic impacts decreased by up to 96%. The septic system used for wastewater treatment contributes to 41% of the global warming potential [GWP, kg CO2eq (carbon dioxide equivalent)] over the building's assumed 100-year lifespan due to methane emissions. The on-site solar panels generate more electricity than the site demands, allowing for 44,000 kWh of green energy to be returned to the grid based on 1 year of performance. Lastly, an exploratory scenario analysis performed on multiple waste streams for structural materials shows that the GWP impacts for the end-of-life could vary from +14,000 to −10,500 kg CO2eq depending on the waste stream. The results of this LCA indicate that the case study building is net-zero energy and water, but not net-zero carbon.