System Boundary Selection in Life-Cycle Inventories Using Hybrid Approaches

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• 作者：Sangwon Suh ; Manfred Lenzen ; Graham J. Treloar ; Hiroki Hondo ; Arpad Horvath ; Gjalt Huppes ; Olivier Jolliet ; Uwe Klann ; Wolfram Krewitt ; Yuichi Moriguchi ; Jesper Munksgaard ; and Gregory Norris
• 刊名：Environmental Science & Technology
• 出版年：2004
• 出版时间：February 1, 2004
• 年：2004
• 卷：38
• 期：3
• 页码：657 - 664
• 全文大小：78K
• 年卷期：v.38,no.3(February 1, 2004)
• ISSN：1520-5851

文摘

Life-cycle assessment (LCA) is a method for evaluatingthe environmental impacts of products holistically,including direct and supply chain impacts. The currentLCA methodologies and the standards by the InternationalOrganization for Standardization (ISO) impose practicaldifficulties for drawing system boundaries; decisions oninclusion or exclusion of processes in an analysis (the cutoffcriteria) are typically not made on a scientific basis. Inparticular, the requirement of deciding which processescould be excluded from the inventory can be rather difficultto meet because many excluded processes have oftennever been assessed by the practitioner, and therefore, theirnegligibility cannot be guaranteed. LCA studies utilizingeconomic input-output analysis have shown that, in practice,excluded processes can contribute as much to theproduct system under study as included processes; thus,the subjective determination of the system boundary maylead to invalid results. System boundaries in LCA arediscussed herein with particular attention to outlining hybridapproaches as methods for resolving the boundaryselection problem in LCA. An input-output model can beused to describe at least a part of a product system,and an ISO-compatible system boundary selectionprocedure can be designed by applying hybrid input-output-assisted approaches. There are several hybrid input-output analysis-based LCA methods that can be implementedin practice for broadening system boundary and also forISO compliance.