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Characterisation factors for default impact assessment categories

This is an updated list of the characterisation factors to be used for the default environmental impact categories. This page is updated on a regular basis so check back for updates when creating an EPD®.

The latest update to the recommendations was made 2016-01-29. Please note the changes for Global Warming Potential.

Default environmental impact categories

Different forms of resources use and pollutants emissions identified in the life cycle inventory work usually have different potential environmental impacts within so-called impact categories. The potential environmental impact is calculated using characterisation methods that associate the scale of a pollutant emission to selected so-called characterisation/conversion factors. Based on this background data and conversion factors the potential environmental impact can be calculated.

The characterisation models and factors to use for the default impact categories are available in the table below:  

Impact category (Unit) Characterisation factors Original reference(s) Examples

Acidification potential


(kg SO2 eq.)

AP, CML 2001 non-baseline (fate not included), Version: January 2016.


Please notice the use of non-baseline characterisation factors for acidification potential.

Hauschild & Wenzel (1998) 1 kg ammonia = 1.88 kg SO2 eq.
1 kg nitrogen dioxide = 0.7 kg SO2 eq.
1 kg sulphur dioxide = 1 kg SO2 eq.

Eutrophication potential


(kg PO43- eq.)

EP, CML 2001 baseline (fate not included), Version: January 2016. Heijungs et al. (1992)

1 kg phosphate = 1 kg PO43- eq.


1 kg ammonia = 0.35 kg kg PO43- eq.


1 kg COD (to freshwater) = 0.022 kg kg PO43- eq.

Global warming potential


(kg CO2 eq.)

GWP100, CML 2001 baseline Version: January 2016.

IPCC (2013)


Updated January 2016

1 kg carbon dioxide = 1 kg CO2 eq.


1 kg methane = 28* kg CO2 eq.


1 kg dinitrogen oxide = 265 kg CO2 eq.

Photochemical oxidant creation potential


(kg C2H4 eq.)

POCP, CML 2001 baseline (high NOx), Version: January 2016.


Please note that this method lacks a characterisation factor for NOx (unspecific). These emissions LCI must therefore be calculated as NO and NO2.


For non-specific hydrocarbons, see table below.

Jenkin & Hayman (1999),



Derwent et al. (1998)

1 kg carbon monoxide = 0.027 kg C2H4 eq.


1 kg ethane = 0.123 kg C2H4 eq.


1 kg toluene = 0.637 kg C2H4 eq.

* Please note that the original source, IPCC (2013), differentiates "Fossil methane" from methane.

For construction product EPDs compliant with EN 15804, table 3 provided in EN 15804 (“Parameters describing environmental impacts”) shall be applied in the PCR instead of the indicators listed above. Characterisation factors are available in Annex C of the standard

To find corresponding methods available in your LCA software, such as SimaPro, GaBi or openLCA, please contact your LCA software provider. To see the compliance of different versions of the CML-IA, see the version history available on their website.

The source and version of the characterisation models and factors used shall be reported in the EPD. Alternative regional LCIA methods with other characterization factors are allowed to be calculated and displayed in addition to the default characterisation factors. The EPD shall contain a clear explanation to what the difference is between the different sets of indicators, as they may appear to a non-expert to display duplicate information regarding the same environmental impact category.

The EPD or its supplementary materials may provide information about the different environmental impact categories displayed in the EPD, including their global/regional characteristics.

POCP for non-specific hydrocarbons

As the CML 2001 baseline method for POCP lacks a characterisation factor for NOx (unspecific), these emissions must therefore be calculated as NO and NO2 in the Life Cycle Inventory (LCI).

VOC mix Characterisation factor, POCP (kg C2H4 eq.) Reference
Hydrocarbons (average) 0.337 *
Non-methane hydrocarbons (average) 0.416 *
Petrol car, evaporation 0.46 **
Petrol car, evaporation 0.42 **
Diesel car, combustion emission 0.48 **
Stationary combustion 0.44 **
Use of solvents 0.29 **
Industrial process 0.27 **
Oil refinement and distribution 0.42 **
Leakage of natural gas 0.24 **

 * Heijungs et al., 1992, in Nordic Guidelines on Life-Cycle Assessment, Nord 1995:20, Nordic Council of Ministers, Copenhagen.
** Andersson-Sköld et al., 1992, in Environmental Assessment of Products, Institute for Product Development, Copenhagen, Denmark.

Additional indicators

In order to better characterise the environmental performance of a product category, the relevant PCR shall indicate the mandatory or voluntary use of other categories of potential impacts. All environmentally-relevant indicators for the product category shall be included.

Examples of such environmental impact categories to include in the PCR are:

  • emission of ozone-depleting gases (expressed as the sum of ozone-depleting potential in mass of CFC 11-equivalents, 20 years)
  • land use and land use change,
  • abiotic resource depletion.

References for the source and version characterisation models and factors used shall be given in the PCR and reported in the EPD.