GaBi Solutions

CML 2001

Description of the CML 2001 Method



CML 2001 is an impact assessment method which restricts quantitative modelling to early stages in the cause-effect chain to limit uncertainties. Results are grouped in midpoint categories according to common mechanisms (e.g. climate change) or commonly accepted groupings (e.g. ecotoxicity).




CML 2001 is developed by the Institute of Environmental Sciences, Leiden University, The Netherlands, and is published in a handbook with several different authors, see literature below. The main principles behind the methodology are not being further developed.

A Microsoft Excel spreadsheet with characterisation factors for more than 1700 different flows can be downloaded from the CML website. The characterisation factors are updated when new knowledge on substance level is available.
Several additional characterisation factors are calculated by thinkstep and LBP-GaBi following the principles described in the CML 2001 methodology documents.


thinkstep and IABP-GaBi cannot be held responsible for any of this information and data.

For more detailed information and questions please contact the given references.




Normalisation factors for CML 2001 are available for EU and the World. The normalisation factors are calculated via total substance emissions and characterisation factors per substance, and are hence following the substance level updates as described above.

Normalisation data for other countries (e.g. Germany, USA and Japan) and geographical units (e.g. North America or OECD) can be scaled from the original CML 2001 normalisation via gross domestic product but is not available in GaBi by default.


For detailed information and questions please contact the given references.




[1] Methodology principles:
Guinée, J.B.; Gorrée, M.; Heijungs, R.; Huppes, G.; Kleijn, R.; Koning, A. de; Oers, L. van; Wegener Sleeswijk, A.; Suh, S.; Udo de Haes, H.A.; Bruijn, H. de; Duin, R. van; Huijbregts, M.A.J. Handbook on life cycle assessment. Operational guide to the ISO standards. I: LCA in perspective. IIa: Guide. IIb: Operational annex. III: Scientific background. Kluwer Academic Publishers, ISBN 1-4020-0228-9, Dordrecht, 2002, 692 pp.

[2] Characterisation factors:

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