Towards Environmental Profiling for Office Buildings Using Life Cycle Assessment (LCA).

Abstract

The purpose of this study is to quantify and compare the potential environmental impacts caused by office buildings throughout their entire life cycle, from extraction of raw materials to disposal of waste. The study also demonstrates how LCA could be applied from a single material to complex systems such as buildings. A multiple case study method has been used with the LCA to determine which life cycle phase (manufacturing of materials, construction, operation, maintenance, and demolition) contributes the most to the total impacts. The study also identifies how the building key assembly systems (foundations, structure, walls, floors, roofs) influence its environmental impacts during its service life. Three recently-built typical office buildings are used as cases in southeast Michigan along with a streamlined LCA approach to quantify the impacts. Furthermore, the study performed a sensitivity analysis to evaluate the effects of possible materials changes of some of building assembly components and examine the change on the total impacts during 60 years of life. The study finds that the operation phase of the building has the highest impacts (90+% of total impacts) during its 60 years life cycle in the following impact categories: total energy (fossil fuel) consumption, global warming, acidification, and human health respiratory effects. Manufacturing phase has the highest impact in the following impact categories: ozone depletion with 87% of total impact, and in eutrophication with 65% of total impact respectively. Furthermore, the study finds that walls system in all building cases has the highest contribution in the following impacts: global warming (26%), acidification (40%), smog potential (35%), and respiratory effect potential (57%). Structure system has the highest contribution to total energy consumption (31%) and to eutrophication (56%) categories. Roofs system has also significant impacts contribution (second to structure) to energy consumption (27%), global warming (17%), and comes second to walls contributing in smog potential (29%). Foundations system contributes the most to ozone depletion at 58%. Through conducting a sensitivity analysis to the results, the study also find that replacing impact-sensitive building materials with more environmental-friendly alternatives yields reduction in total impacts by 6%-15% in different impact categories.