Life cycle assessment (LCA) of a LEED-certified green building using two different LCA tools

Aygenç, Merve
In this study, Life Cycle Assessment (LCA) tool was used for analyzing the environmental effects of the green buildings associated with one of the world-wide used Green Building Rating Systems (GBRS) called Leadership in Energy and Environmental Design (LEED). The ultimate goal here is to contribute to the integration of LCA into LEED rating system. The secondary objectives were to execute several LCAs of both a hypothetical conventional building and an actual green building to compare the results of two different LCA softwares as One Click LCA and SimaPro and also to measure the level of sustainability of the actual green building. For the first purpose, LCA study was performed to a selected case study building having LEED v2009 Platinum certification by using two different LCA program called One Click LCA and SimaPro. The system boundary was selected as A1, A2, A3, A4, B4, B5, C3 and C4 according to EN Standards. For the second objective, another LCA was performed in SimaPro for the case study building by taking a hypothetical conventional building as a reference. In this case, system boundary was determined as A1, A2, A3, A4, B1, B4, B6, B7, C2, C3, C4 and D. In both tasks, functional unit was set as “meter square of the building”. Impact categories of “Global Warming Potential (GWP)”, “Ozone Layer Depletion (OPD)”, “Potential (AP)”, “Eutrophication Potential (EP)”, “Photochemical Ozone Formation Potential (POFP)” and “Abiotic Depletion Potential-Fossil Fuel (ADP-Fossil Fuel)” were considered. CML 2002 method was used in One Click LCA while CML IA Baseline was chosen in SimaPro. For the first objective, the results were only compared based on characterization values since One Click LCA does not give normalized results. Accordingly, results showed that One Click LCA and SimaPro showed highly comparable results in all impact categories except POFP and ADP-Fossil fuel due to the slight difference in system boundaries. In these impact categories, One Click LCA gives 58% and 32% higher results, respectively. For the second objective, environmental effects of the baseline building were found to be significantly higher than the case study building results in all impact categories. In both LCAs, natural gas, steel, concrete and aluminium cladding displayed significant impacts, commonly. However, huge discrepancies occurred in the results due to photovoltaic panels eliminating electricity use during operation together with the aluminium & PVC frame windows and recycling option in the disposal scenarios.