Both completing system boundaries and realistic modeling of the economy are of interest for life cycle assessment—a reply to “Moving from completing system boundaries to more realistic modeling of the economy in life cycle assessment” by Yang and Heijungs (2018)
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As Yang and Heijungs (Int J Life Cycle Assess https://doi.org/10.1007/s11367-018-1532-y, 2018) bring forward, there is indeed a need for “more realistic modeling of the economy” in LCA. However, what I discuss in this letter is that this does not imply that research should be “moving from completing system boundaries to more realistic modeling” or that “hybrid LCA with further linear sophistication is a step forward in the wrong direction”, as Yang and Heijungs (2018) state. Five arguments are brought forward as to why not: (1) completing system boundaries is a fundamental aspect of LCA; (2) the approach that leads to a higher accuracy in LCA will in practice remain relative and case dependent; (3) the general argument of hybrid LCA is not that every economic activity is in theory connected; (4) hybrid LCA is applied for more reasons than just completing system boundaries; and (5) hybrid LCA is more a step forward in a pragmatic data-driven direction, which is not a wrong direction. Finally, I propose that a more broad empirical study is needed to pinpoint which type of adaptation might most probably lead to higher accuracy, keeping in mind that this still will never be completely generalizable.
KeywordsCompleting system boundaries Realistic modeling Life cycle assessment Hybrid LCA Linear modeling
I thank Dr. Thomas Gibon, Prof. Manfred Lenzen, and Dr. Franceso Pomponi for the valuable feedback that has improved the manuscript.
- Gibon T, Schaubroeck T (2017) Lifting the fog on characteristics and limitations of hybrid LCA—a reply to “Does hybrid LCA with a complete system boundary yield adequate results for product promotion?” by Yi Yang (Int J Life Cycle Assess 22(3):456–406, doi:10.1007/s11367-016-1256-9. Int J Life Cycle Assess https://doi.org/10.1007/s11367-017-1291-1, 22, 1005, 1008
- Gibon T, Wood R, Arvesen A, Bergesen JD, Suh S, Hertwich EG (2015) A methodology for integrated, multiregional life cycle assessment scenarios under large-scale technological change. Environ Sci Technol 49, 11218–11226. https://doi.org/10.1021/acs.est.5b01558
- Yang Y, Heijungs R (2018) Moving from completing system boundaries to more realistic modeling of the economy in life cycle assessment. Int J Life Cycle Assess. https://doi.org/10.1007/s11367-018-1532-y