Blog archive: March 2017
March 15, 2017 by Bo Weidema
It will come as no surprise to regular readers of this blog that 2.-0 LCA consultants advocates a strict interpretation of the ISO 14040-series of standards for LCA to mean that a consequential modelling approach shall be used whenever the results are to be applied for decision support. Our advocacy for the consequential approach is based on its superior ability to reflect the physical and economic causality of changes in product systems.
The alternative modelling approach, which has come to be known as attributional, is nevertheless still in widespread use, even for product comparisons, supporting decisions that will shift demand between products, and to estimate the effect of increasing or decreasing system output. This points to a widespread lack of understanding of the limitations of attributional models. We have therefore spent quite some effort in explaining the difference between the two modelling approaches and their application areas.
These efforts include two recent scientific articles that contribute to solve the internal consistency problems in attributional modelling and clarify the importance of making the right choice of background data depending on the application area, based on an understanding of underlying reasons for the differences in results between the two modelling approaches.
Currently, ISO is investigating options for making amendments to overcome the largest problems in the current LCA standards. Through our national standardisation committee we have recently submitted a proposal to amend ISO 14044 on the topic of “Applications of LCA” aiming at clarifying how the requirements of the standard should be interpreted when applying each of the two approaches, both with respect to application areas, system boundaries, and co-product allocation. We urge all our readers to ask your national standardisation body to support that ISO initiates discussion on this proposed amendment.