Allocation in ISO 14041—a critical review

The adequacy and feasibility of methods recommended for allocation by the current international standard on life cycle inventory analysis (LCI) are reviewed. The review is based on the view that an LCI should provide information on the environmental consequences of manipulating technological systems. On this basis, subdivision and allocation based on physical, causal relationships are adequate methods to deal with allocation problems for certain multifunction processes where the production volume of exported functions are unaffected. Further research is needed to develop methods that can deal with a broader range of processes. System expansion is an adequate method when exported functions are affected if data can be obtained for the competing production of the exported function, and if the data uncertainties are not too large. In LCI practice, system expansion is often based on inaccurate data on the effects on the exported functions as well as on the indirect effects of changes in the exported functions. Further research is needed to establish what data should be used at system expansion. Other approaches to the allocation problems are adequate only where the effects on the LCI results are small. The ISO procedure should be revised to take into account the type of information provided by the different methods.