CONCLUSIONS AND POINTERS

There can be large discrepancies in the results of LCAs even when performed on identical product alternatives. Hence, it is important to know how to identify the differences between studies which can explain these discrepancies. The following questions address the most frequent sources of discrepancies  

It is important to ensure that the chosen functional unit is suitable for the goal of the study. The functional unit is the basis for the definition of the product system and thus also affects the selection of processes and impacts to be included in the study. Using a process tree that is incoherent with the goal or with the functional unit will certainly provide a result, but this result will not necessarily be relevant to the question posed in the beginning of the study. 

As already pointed out, impact assessment methodologies are undergoing intense development, and new approaches regularly appear. It may be worthwhile to try a number of different methods to confirm the result of impact assessment. 

It is easy to highlight weaknesses of LCA, but this is not a sufficient argument to abstain from its use. Despite the inherent uncertainties of LCA, it has been shown to be an efficient tool for improving the environmental performance of products and processes. 

Complete LCAs are still very time consuming. Periods of up to three person-montiis are frequent for studies where considerable amounts of data are already available, and times approaching a person-year may be necessary for studies with lower availability of data [8]. The latter kind is currently only justified for long-term strategic planning or compliance with legislation. 

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