Life cycle assessment (LCA) requires an iterative approach through various phases, in which one first performs a preliminary evaluation of the system to determine the order of magnitude of the different contributions, and then performs a more detailed study of the important points previously highlighted. Each phase of an LCA has major objectives and pitfalls to be avoided. The following paragraphs summarize the key points of each phase (Figure 7.1) and highlight critical issues on which to focus attention. Moreover, Appendix IV summarizes the forms to fill out for each LCA phase, reminding the reader of the key points in each phase, as well as the information that needs to be gathered and analyzed.