1 D r a f t Life Cycle Assessment A product-oriented method for sustainability analysis UNEP LCA Training Kit Module i – The mathematics of LCIA

Characterisation models Characterisation factors The characterisation step Contents D r a f t

3 3 Characterisation models mass (or concentration) impact

4 4 D r a f t Characterisation factors (1) mass (or concentration) impact

5 5 D r a f t Characterisation factors (2) Infinitesimal small change: Substance and category dependence: Multiple substance dependence

6 6 D r a f t Characterisation models (1) Characterization models express the relationship between the category indictor and the outputs Characterization factors are derived from models that predict the impact

7 7 D r a f t Characterisation models (2) Often developed outside LCA –IPCC, WMO, … derivative –linearised model –only valid for small change partial derivative –constant background

8 8 D r a f t The characterisation step (1) Conversion and aggregation –conversion –aggregation –together

9 9 D r a f t The characterisation step (2) Or in matrix form or even more condensed –here no problems with inversion or non-square matrices