Method based on market changes for improvement of comparative attributional life cycle assessments

Purpose Current comparative life cycle assessment (LCA) studies claim to answer whether it is better or worse for the environment to change from old to new systems. Most commonly, the attributional LCA (ALCA) is practised despite its limitations to describe market effects. Hence, an attempt is done here to include market effects in the ALCA practice for comparisons in order to improve ALCA. The purpose is neither to investigate which LCA concept, ALCA, consequential LCA or decisional LCA, is the best for comparisons nor which is the best for decision-making. Methods Here, for the first time, a method based on marked changes which can be used for sensitivity checks of comparative ALCAs, advanced ALCA (AALCA) is presented. The new concept of global change mix factors (GCMF) is introduced. The method, based on accessible market data, is applied to previous comparative ALCAs of conductive adhesives, cooling modules used in radio base stations, office computing systems, as well as personal devices usage, here represented by multifunctional smartphones replacing other devices such as digital cameras. Results and discussion The results show that AALCA based on market data improves the understanding and can act as a sensitivity check of comparative ALCA results. For declining markets of products, with relatively high eco-environmental impacts, the difference between comparative AALCA and ALCA can be significant. As AALCA is founded in marginal electricity thinking and uses market data, there are similarities between AALCA and simplistic consequential LCA (CLCA). However, AALCA is not intended to replace CLCA or decisional LCA (DLCA). Conclusions By applying allocation factors, GCMF, based on real or future market changes, the interdependence of global markets and micro-level LCA shifts can be taken into account in comparative micro-level ALCA studies and make them more robust. Further, the sensitivity of using price units instead of physical units, as the basis for the GCMF, should be investigated. The degree to which AALCA and CLCA can complement each other should be examined. Also, the degree to which the GCMF used in AALCA-H address rebound effects should be further explored. The annual eco-environmental impacts of mobile devices towards 2020 are also of interest, and more LCA case studies are welcome.