Session “Midpoint, endpoint or single score for decision-making?”—SETAC Europe 25th Annual Meeting, May 5th, 2015

Abstract

There is a strong demand for simple, understandable and clear LCA outcomes to support decision-making especially in the context of policy-making or company management. The debate is ongoing as to whether clarity and simplicity may be obtained by adopting either LCA endpoint or even single score methods. As a contribution to this debate, a session was organised to discuss the use of midpoint, endpoint or single score indicators in support of the decision making process. The session, comprising 10 presentations about different aspects of this topic, concluded with a 40 minute panel discussion. Most authors who contributed to this SETAC Europe LCA session concluded there was a need for endpoint or single score assessment (and transparent communication of the same) for sound and effective decision-making support. This may be the better option than letting the decision makers choose the relevant impacts subjectively. But endpoint or single score results do not mean that midpoint indicators have no value. Even though endpoint or single score indicators can be very helpful in decision support, midpoint indicators help identify issues of specific environmental concern (e.g. climate change, acidification or water scarcity).

Addendum: overview of the plenary presentations

As an adequate assessment of the inherent uncertainties is relevant in LCA midpoint indicators and single-scoring methodologies, the first presentation given by Jeroen Guinée (Leiden University) was about the important and correct use of uncertainty considerations in comparative studies.

Sebastien Humbert (Quantis) discussed how to use damage-oriented knowledge to increase analysis capacity. This allows an identification of which indicators dominate “absolute” impacts and should be of prime concern when making a choice between two products. Information based on endpoint and/or damage-oriented methods such as IMPACT 2002+, ReCiPe or IMPACT World+ are used to generate conversion factors to assess the 15 impacts categories of PEF/OEF using endpoint in addition to midpoint indicators.

Serenella Sala (Joint Research Centre) presented a set of weighting factors based on the application of a distance-to-target approach for Europe in 2020. Different approaches for normalising and weighting the PEF/OEF midpoint categories to single score were presented, in order to identify their difference in highlighting the most relevant impact categories in a given region or for a given product (e.g. if they were applied in the context of defining Product Environmental Footprint Category Rules (PEFCRs)).

Rolf Frischknecht (treeze Ltd.) presented a study about the environmental impacts of products and services consumed in Switzerland over time. Single-score indicators were used in order to show the bigger picture and to identify hotspots in the consumption-based environmental impact of a nation, whereas midpoint indicators could help to identify specific reduction targets and develop measures to achieve them.

Jacob Lindberg’s presentation (Swedish Environmental Research Institute) was about monetisation as a valuable concept for single-score information. A study was conducted by AkzoNobel’s Sustainability Department to explore the issue of economic assessment of environmental impacts. The three different monetisation methods—EPS, Stepwise and Ecovalue—were compared and analysed in a case study, comparing different decorative paints with regard to their environmental performance. One observation was the usefulness of including several methods to overcome data gaps and reduce uncertainties.

Liselotte Schebek (Technische Universität Darmstadt) presented results from a project carried out by SYRCON, Dr. Ahbe and TU Darmstadt on behalf of the Volkswagen Group Research Environment to adapt the Swiss Method of Ecological Scarcity to German framework conditions. The Swiss method was adapted to allow for actual and critical flows from German legal targets (e.g. as to immission levels) or policy targets (e.g. as to GHG reduction). Ms Schebek highlighted that often natural science cannot yet provide clear limits for environmental impacts, and that political targets are formulated by democratic procedures, reflecting a consensus process of stakeholders. In this sense, the method of Ecological Scarcity is more suitable specifically for use in environmental management and when needing to incorporate societal goals in decision-making of companies.

Urs Schenker (Nestlé Research Centre) showed Nestlé’s new approach to normalise selected midpoint indicators through their eco-design tool. He pointed out that whilst the different normalised indicator scores are not added together, the fact that they are displayed next to each other allow the identification of those indicators that matter most for any given product system. He stressed that transparency is highly relevant and that single scores often lack this transparency.

Steven De Mester (Ghent University) presented the PROSUITE (aggregation) methodology for sustainability assessment based on a biorefinery case study. The final PROSUITE framework consists of a selection of 40 midpoint indicators of relevant social, economic and environmental aspects and grouped this into 5 endpoints, namely impact on social well being, prosperity, exhaustible resources, natural environment and human health. Conclusions were formulated on how such a complex assessment methodology should be interpreted and communicated.

Tommie Ponsioen (PRé Consultants) showed that stakeholder weighting at midpoint level is unreliable due to the large number of impact categories and because the concepts can be difficult to grasp. An alternative solution to directly using endpoints to determine the relevant impact categories or single scores is to use weighting factors on midpoint categories that are obtained by using an endpoint method including weighting at endpoint. Midpoint weighing factors based on endpoints will provide decision-makers with much more realistic information on which categories are important for the studied product than midpoint panel weighting factors.

Fredy Dinkel (Carbotech AG) discussed in his presentation the necessity of single-score results for decision support. It is crucial to understand the relevance of the different midpoint indicators. For this, single-score methods based on consensus and not merely personal opinions are not only helpful, but necessary. In order to reach a sound decision, different single-score methods should be used to conduct sensitivity analysis, which allows assessing the consequences on the LCIA results due to different value-choices of the weighting methods.