- 5th February 2020
By Dr Jaqi Lee, S2A Associates, Sustainability Systems Analysis
There is a standing joke amongst life cycle assessment (LCA) practitioners that the answer to any environmental or sustainable assessment is ‘it depends’. Facetious as this sounds, it is unfortunately true. Answers are highly dependent on where the system boundaries are drawn, what assumptions are made, what data is used, and also, exactly what question the study is trying to answer.
The first difficulty in getting to the right answer to the issues above lie in the communication between those who are asking the question, and those who are trying to answer it. Frequently a LCA is requested, yet the question would be better answered using a different technique. For example, a material flow assessment would be a much better way to understand what materials are used in a system, where they end up and in what form. But if we assume that a LCA is the right approach, the majority of the benefit comes from the improved understanding of the system under review, and the best way to get that is to be actively involved in the analysis, to walk around production facilities etc and ask questions. This is often the way in which discrepancies between practice and the way an organisation thinks things are done are found. Too often these learnings are lost because the practitioner does the digging and then prepares a report that probably only covers a fraction of the ‘little’ details found out.
The other assumption that can face the LCA practitioner when delivering results is that the ‘number’ produced at the end is highly accurate. This is an issue for both comparative studies, where a small difference in results between two alternatives is taken as statistically significant, and for standalone systems, where the number is assumed to be ‘right’. To be fair, for detailed LCA studies using more measured data and sensibly applied uncertainty, these issues can be significantly reduced, but not entirely eliminated. For studies that are dealing with new products, processes or potential changes to existing systems that have not yet been implemented, the right quality of data is often missing, proxy data and assumptions are everywhere, and the resulting outcomes can be easily read as more factual than they really are.
And this is where the danger lies. Results from LCA type studies always need to be read with a clear understanding of the boundaries, assumptions made and data coverage; it is not unknown for a study use predominantly energy data for certain stages of the life cycle.
Life cycle assessment is an incredibly useful tool, and the best one we have for assessing the environmental implications of a product, process or wider system. It can be and is used to great effect, but please, the devil really is in the detail. The results are always a case of ‘it depends’.