Methodology of ecoinvent 3

Methodology of ecoinvent 3

Did the characterisation factors of a specific LCIA method change? Why is the LCIA score of a certain product not the same in the ecoinvent database and in my software tool?

Reasons for changes the characerisation factors

Impact assessment methods are regularly updated to reflect the newest scientific advances, the inclusion of new mechanisms of cause-and-effect, newer data, etc. Ecoinvent uses the results published by method developers to calculate the impacts of the calculated life cycle inventories (LCI).


The implementation of impact assessment methods is not always straightforward and unambiguous. The method developers often calculate characterisation factors (CFs) with assumptions that are not compatible with the results of LCIs.

 

For example, some methods require precise knowledge of geographical location of an emission to select the appropriate CF.

 

Other methods ask for information about some properties of the emissions, like water quality. Some methods characterise for example dissipative use of water or materials, when this information is not directly present in the LCI.

Method developers often use different naming conventions than ecoinvent for chemicals, land use and material extraction elementary exchanges. In most cases, CAS number can help, but these are not always present, or for some substances like pesticides, commercial names are ambiguous, contain a mix of active substances and therefore report more than one CAS number.


Some methods do not carry CFs for a substance in all the sub compartments present in ecoinvent. For example, should a chemical emission to groundwater receive the same CF as the same emission to surface water, if the groundwater CF is not explicitly mentioned in the method?


Different actors (method developer, database managers, software developer) might have a different opinion about how to resolve ambiguities.

 

Finally, plain old human mistakes is bound to happen when managing and aggregating a large quantity of information coming from disparate sources.

Reason for different scores in ecoinvent and the LCA software

For all these reasons, CFs used by ecoinvent sometimes differ from what is found in software. Ecoinvent is not in a position to impose its implementation choices to the other actors in LCA. The actors in the LCA community are mostly divided by their specialisation: inventory and impact assessment. The implementation of impact assessment methods on the inventory sits uncomfortably at the interface of these two specialisations. There is no regulatory body acting as an authority for this particular task.

Transparent implementation

Ecoinvent has started taken the following steps in the direction of greater transparency:

  • Better LCIA implementation documentation. The file section of ecoQuery contains a detailed implementation report, showing the source of the CFs and how they were mapped to the ecoinvent elementary exchanges. These reports are reviewed by independent experts or by the method developer.
  • Documentation of implementation differences with software. Ecoinvent has started to engage with software developers to minimise those differences. Prior to a release, the implementation is shared to the software and differences are identified. The source of these differences is discussed, and a spreadsheet is available in the file section of ecoQuery for users with a licence.

Where to find the LCIA results and supporting documents

All the documentation and supporting files are available in the files section in the ecoQuery accessible to the users of the database who hold valid ecoinvent licence.

For further information about LCIA implementation, please contact support@ecoinvent.org.