According to the ISO 14040 standard on life cycle assessments, there are 4 stages of an LCA: (1) Goal and Scope, (2) Inventory Analysis, (3) Impact Assessment, and (4) Interpretation. We explored Inventory Analysis, which ISO 14040 defines as “the phase of life cycle assessment involving the compilation and quantification of inputs and outputs for a product throughout its life cycle”, in the previous posts on reference flows, assumptions behind reference flow calculations, and unit processes. Life Cycle Impact Assessment was also described and defined. We are now left to describe and interpret the results of our LCA. In this post, the principles of LCA interpretation will be described – those interested in exploring the results of Ecosystem Analytics Inc.’s LCA on cloth handkerchief versus paper facial tissue use should either read the executive summary or the full LCA report.
Interpretation, from ISO 14040, is the phase of LCA in which the findings from the inventory analysis and the impact assessment are considered together. We present the results of our LCA study and evaluate those results with respect to previously published studies. It is also important to describe the LCA study’s limitations and explore how the study limitations affect the conclusions that can be made. Interpretation must also include the evaluation of the results of the study in relation to the defined goal and scope. This harkens to the iterative nature of LCA, in which information of each step of the LCA informs and helps refine the overall assessment.
The astute reader might have noticed that we have not yet described the Goal and Scope of this LCA. We will conclude our LCA series by rounding back to a description of the Goal and Scope phase, and demonstrate how the concepts we have been discussing throughout this series feed into it.