Spatial differentiation in characterisation modelling – what difference does it make?

In the life cycle of a product, emissions take place at many different locations. The location of the sources and its surrounding condition influence the fate of the emission and the exposure it leads to but this source of variation is currently neglected in life cycle impact assessment, although it is well known that the impacts predicted by site-generic LCIA in some cases differ significantly from the actual impacts,. Indeed, there are eloquent examples where the spatially determined variation in impact for one substance clearly exceeds the variation in impact between different substances. Recent results from the Danish LCA Methodology Development and Consensus Creation Project address this issue and provides a framework for spatially differentiated characterisation modelling together with easily applicable site-dependent factors for each European country and normalisation references for those impact categories commonly addressed in LCA (EDIP2003 methodology). The site-dependent factors are backed by site-generic factors to be used for those processes of the life cycle where the location of emission is unknown. Compared to traditional midpoint characterisation modelling, this novel approach is spatially resolved and comprises a larger part of the cause-effect chain including exposure assessment and in some cases exceeding of threshold values, which positions it closer to endpoint modelling. Examples are given where conclusions are reversed when the site-dependent characterisation modelling is used instead of the conventional site-generic modelling.