2008 Volume 4 Issue 3 Pages 260-269
Objective. Generally, the environmental impacts of products are assessed based on the deterministic data (ex. mean value) for inventory analysis and impact assessment in life cycle assessment. However, both inventory data and impact factors have some uncertainties. In this research, a case study for passenger car was conducted for clearly showing the importance of uncertainty analysis in LCA.
Results and Discussion. Inventory data containing statistical data were referred to Ecoinvent (LCI database in Switzerland) and some part of the data were revised to reflect Japanese conditions based on the LCI data provided by Japan Automobile Research Institute (JARI). “Life cycle Impact assessment Method based on Endpoint modeling (LIME)” was applied as an impact assessment method, and uncertainty data of impact factors were obtained based on Monte-Carlo simulation by using results of the investigation for statistical information of each parameter. In the comparison of gasoline-powered vehicle (GV, 2000 regulation) and diesel-powered vehicle (DV, 2002 regulation), the environmental impact of DV was higher in the assessment based on deterministic data. However, the results of uncertainty analysis quantitatively showed that the conclusion obtained from the deterministic analysis was not always supported, indicating that there are still 34% possibility for suggesting the opposite conclusion. Factors with high sensitivity on the uncertainty of impact assessment results have been clarified, and the revision of the factors (damage factors for urban air pollution) for reflecting more realistic conditions could have provided more reasonable results.
Conclusions. The uncertainty analysis in LCA will be helpful for assessing and improving the reliability of the results and support the decision making in product selection and policy planning with more confidential and high responsible information.
