Weighting for LCA based Tools, Methods and Ecolabels – Practical but Contentious! Edge Environment paper for the 7th Australian Conference on Life Cycle Assessment in March 2011:
This paper explores the derivation and use of weighting factors to interpret LCIA results from midpoint impact measures to a final score. The different methods used internationally are briefly reviewed with their strengths and limitations. Results derived from an approach developed in the UK and applied also in the US, NZ and 11 locations around Australia are presented showing a high level of consistency in stakeholders perceptions over time, between countries, between regions, between stakeholders and between different demographic groups, but with some issues showing departures for understandable reasons. The influence of media on the results is also illustrated. The paper then explores how these results can be practically used in LCIA studies to interpret multi-impact results and communicate complexity simply to the public. Examples of the use of weightings in LCA studies, in LCA based design tools for buildings, in scoring environmental attributes in ecolabels and in building Rating Tools are also presented.