Suh Sangwon, Lenzen Manfred, Treloar Graham J, Hondo Hiroki, Horvath Arpad, Huppes Gjalt, Jolliet Olivier, Klann Uwe, Krewitt Wolfram, Moriguchi Yuichi, Munksgaard Jesper, Norris Gregory
CML, Leiden University, P.O. Box, 9518, 2300RA, Leiden, The Netherlands.
Environ Sci Technol. 2004 Feb 1;38(3):657-64. doi: 10.1021/es0263745.
Life-cycle assessment (LCA) is a method for evaluating the environmental impacts of products holistically, including direct and supply chain impacts. The current LCA methodologies and the standards by the International Organization for Standardization (ISO) impose practical difficulties for drawing system boundaries; decisions on inclusion or exclusion of processes in an analysis (the cutoff criteria) are typically not made on a scientific basis. In particular, the requirement of deciding which processes could be excluded from the inventory can be rather difficult to meet because many excluded processes have often never been assessed by the practitioner, and therefore, their negligibility cannot be guaranteed. LCA studies utilizing economic input-output analysis have shown that, in practice, excluded processes can contribute as much to the product system under study as included processes; thus, the subjective determination of the system boundary may lead to invalid results. System boundaries in LCA are discussed herein with particular attention to outlining hybrid approaches as methods for resolving the boundary selection problem in LCA. An input-output model can be used to describe at least a part of a product system, and an ISO-compatible system boundary selection procedure can be designed by applying hybrid input-output-assisted approaches. There are several hybrid input-output analysis-based LCA methods that can be implemented in practice for broadening system boundary and also for ISO compliance.
生命周期评估（LCA）是一种全面评估产品环境影响的方法，包括直接影响和供应链影响。当前的LCA方法以及国际标准化组织（ISO）的标准在划定系统边界方面存在实际困难；关于分析中流程的纳入或排除（截断标准）的决策通常并非基于科学依据做出。特别是，决定哪些流程可以从清单中排除的要求可能很难满足，因为许多被排除的流程通常从未被从业者评估过，因此，无法保证它们可以被忽略不计。利用经济投入产出分析的LCA研究表明，在实践中，被排除的流程对所研究的产品系统的贡献可能与纳入的流程一样大；因此，系统边界的主观确定可能会导致无效结果。本文讨论了LCA中的系统边界，特别关注概述混合方法，将其作为解决LCA中边界选择问题的方法。投入产出模型可用于描述产品系统的至少一部分，并且可以通过应用混合投入产出辅助方法来设计与ISO兼容的系统边界选择程序。有几种基于混合投入产出分析的LCA方法可以在实践中实施，以扩大系统边界并符合ISO标准。
