The Influences on the Results of LCIA by the Allocation Procedures between Different Products

One of the most important and problematic subjects in LCA is how to deal with allocation in calculation. Until now, there are a lot of discussions for this problem including the statement in ISO framework. However, most of the considerations of these issues are limited to the influences of inventory phase, and dose not treat the impact assessment. The author has proposed a weighting methodology in LCIA for Japan. This paper describes the difference of the results of weighting depending on the allocation principle between primary and secondary products with case study. ISO 14041 specifies that where allocation can not be avoided, the inputs and outputs of the system should be partitioned which reflects the underlying physical relationships between different products". We concentrated on the physical partitioning with utilization of mass of products in this case study. Currently, there are a lot of recycle systems. We have considered the influences on the results of weighting by the allocation procedures of material recycle and thermal recycle. The results were dependent on the allocation principles.