METHODS, TOOLS, AND SOFTWARE Life Cycle Assessment Software Selection Can Impact Results Ricky Speck, Susan Selke, Rafael Auras, and James Fitzsimmons Summary When software is used to facilitate life cycle assessments (LCAs), the implicit assumption is that the results obtained are not a function of the choice of software used. LCAs were done in both SimaPro and GaBi for simplified systems of creation and disposal of 1 kilogram each of four basic materials (aluminum, corrugated board, glass, and polyethylene terephthalate) to determine whether there were significant differences in the results. Data files and impact assessment methodologies (Impact 2002, ReCiPe, and TRACI 2) were ostensibly identical (although there were minor variations in the available ReCiPe version between the programs that were investigated). Differences in reported impacts of greater than 20% for at least one of the four materials were found for 9 of the 15 categories in Impact 2002+, 7 of the 18 categories in ReCiPe, and four of the nine categories in TRACI. In some cases, these differences resulted in changes in the relative rankings of the four materials. The causes of the differences for 14 combinations of materials and impact categories were examined by tracing the results back to the life cycle inventory data and the characterization factors in the life cycle impact assessment (LCIA) methods. In all cases examined, a difference in the characterization factors used by the two programs was the cause of the differing results. As a result, when these software programs are used to inform choices, the result can be different conclusions about relative environmental preference that are functions purely of the software implementation of LCIA methods, rather than of the underlying data. Keywords: environmental impact industrial ecology life cycle assessment (LCA) life cycle inventory (LCI) software sustainability Supporting information is available on the JIE Web site Introduction As the world’s demand for goods of all types increases, business and industry are continually looking for ways to improve their environmental footprint. A key requirement in enhancing sustainability of activities is being able to compare the environmental impacts of different options. Without a common basis of comparison, there is no credible means of determining that any option is more environmentally preferable than the others available. Life cycle assessment (LCA) is one approach to estimating environmental impacts that is seeing increasing use (Sonneveld 2000). LCA offers the advantage of looking at the contributions made by each step in the life cycle of a product or process, from Address correspondence to: Susan Selke, 448 Wilson Rd., School of Packaging, Michigan State University, East Lansing, MI 48824-1223, USA. Email: sselke@msu.edu © 2015 by Yale University DOI: 10.1111/jiec.12245 Editor Managing Review: Annie Levasseur Volume 20, Number 1 obtaining the raw materials all the way through to disposal at the end of useful life. Combining this information not only gives a picture of the overall environmental impact of the product or process, but it can also provide a guide for directing efforts to reduce impacts. LCA is not without cost; a major disadvantage associated with LCA is the large effort required to gather all the inventory data and analyze all the necessary information. To help reduce this effort, several databases and software programs have been created to assist in obtaining and analyzing life cycle information. International Organization for Standardization (ISO) 14040 provides the framework for conducting an LCA, and ISO 14044 (ISO 2006a, b) provides guidelines and requirements for conducting an LCA. These standards divide an LCA into four 18 Journal of Industrial Ecology www.wileyonlinelibrary.com/journal/jie