Front. Sustain. Frontiers in Sustainability Front. Sustain. 2673-4524 Frontiers Media S.A. 10.3389/frsus.2021.768194 Sustainability General Commentary Response: Commentary: System Expansion and Substitution in LCA: A Lost Opportunity of ISO 14044 Amendment 2 Heijungs Reinout 1 2 * Allacker Karen 3 Benetto Enrico 4 Brandão Miguel 5 Guinée Jeroen 2 Schaubroeck Simon 3 Schaubroeck Thomas 4 Zamagni Alessandra 6 1Department of Operations Analytics, Vrije Universiteit Amsterdam, Amsterdam, Netherlands 2Institute of Environmental Sciences (CML), Leiden University, Leiden, Netherlands 3Department of Architecture, Faculty of Engineering Science, KU Leuven, Leuven, Belgium 4Luxembourg Institute of Science and Technology, Belvaux, Luxembourg 5Division of Sustainability Assessment and Management, Department of Sustainable Development, Environmental Science and Engineering, School of Architecture and the Built Environment, KTH-Royal Institute of Technology, Stockholm, Sweden 6Ecoinnovazione srl Spin-Off ENEA, Bologna, Italy

Edited by: Mikołaj Owsianiak, Technical University of Denmark, Denmark

Reviewed by: Mélanie Douziech, MINES ParisTech, PSL University, France

 *Correspondence: Reinout Heijungs r.heijungs@vu.nl

This article was submitted to Quantitative Sustainability Assessment, a section of the journal Frontiers in Sustainability

 30 11 2021 2021 2 768194 31 08 2021 29 09 2021 Copyright © 2021 Heijungs, Allacker, Benetto, Brandão, Guinée, Schaubroeck, Schaubroeck and Zamagni. 2021 Heijungs, Allacker, Benetto, Brandão, Guinée, Schaubroeck, Schaubroeck and Zamagni

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 A Commentary on Commentary: System Expansion and Substitution in LCA: A Lost Opportunity of ISO 14044 Amendment 2 by Heijungs, R., Allacker, K., Benetto, E., Brandão, M., Guinée, J., Schaubroeck, S., Schaubroeck, T., and Zamagni, A. (2021). Front. Sustain. 2:692055. doi: 10.3389/frsus.2021.692055 life cycle assessment allocation substitution system expansion ISO

Finkbeiner (2021) comments on our critique (Heijungs et al., 2021) of the amendment to ISO 14044. We summarize hereafter his comment:

According to him, the ISO amendment does not rule out system expansion (in the sense of expanding the functional unit) in favor of substitution (in the sense of subtracting the avoided impacts of coproducts); instead, it is a clarification that both approaches are allowed.

The texts by ISO are comparable to legislative documents, which require knowledge of the rules in order to decipher them.

We thank Finkbeiner for this clarification, and we are happy to read that both procedures (system expansion and substitution) are allowed, according to his interpretation.

Yet, the amendment text is not in line with his interpretation, as pointed out by us and by Schaubroeck et al. (2021). Even if the amendment text is not normative and just informative, consistency and correctness is needed throughout the complete ISO text. Moreover, we are worried by the implication that well-trained scientists interpreted in a different way a text that was intended to provide clarity. We consider ourselves as target audience of these standards, and these are apparently not as “crystal-clear” as Finkbeiner appears to think. Hence, it seems that the amendment has failed in its mission “that it should be clarified, that the “subtraction approach” can also be used as system expansion,” as Finkbeiner phrases the amendment's “actual intention.” A lost opportunity, after all. Let's hope that future ISO amendments are more consistent, and also understandable to the people who are not familiar with the ISO rules.

Author Contributions

RH drafted and edited the text. KA, EB, MB, JG, SS, TS, and AZ suggested additions and improvements. All authors contributed to the article and approved the submitted version.

 Conflict of Interest

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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 References Finkbeiner M. (2021). Commentary: system expansion and substitution in LCA: a lost opportunity of ISO 14044 Amendment 2. Front. Sustain. 2:729267. 10.3389/frsus.2021.729267 Heijungs R. Allacker K. Benetto E. Brandão M. Guinée J. Schaubroeck S. . (2021). System expansion and substitution in LCA: a lost opportunity of ISO 14044 Amendment 2. Front. Sustain. 2:692055. 10.3389/frsus.2021.692055 Schaubroeck T. Schaubroeck S. Heijungs R. Zamagni A. Brandão M. Benetto E. (2021). Attributional & consequential life cycle assessment: definitions, conceptual characteristics and modelling restrictions. Sustainability 13:7386. 10.3390/su13137386