openLCA analysis group vs EN15804 modularity principle

Question

Hello,

I have a question regarding EPD result output using the Analysis Group functionality. When modelling product losses (e.g. installation losses in step A5), I call the modelling of the previous steps (raw material, transport, etc. as shown in following screenshot) to account for the additional impacts.

The problem is that when using Analysis Groups, changing the amount of losses (installation losses in my case) changes the results in other steps (A1 to A4 and C2 to C4 in my case). This happens with openLCA version 2.5.0 (I did not take the time to check on version 2.6.0).

According to EN 15804 modularity principle, losses in step A5 should only affect step A5.

Is there a way around this?

Thanks in advance,

Jocelyn

Answer 1

Hello,

Can you post the screenshot ?

Comments

https://ask.openlca.org/?qa=blob&qa_blobid=14994833858087884822

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For A5, you should not include producing of raw materials impacts (A1-A3), it's only focused on wasting materials and packaging, according to EN15804+A2 standard


It would also help if you show me how you set up your group analysis via model graph.

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To model installation losses (A5), I have to repeat preceeding steps (A1-A4) in A5 due to modularity principle.

Here for the model graph: https://ask.openlca.org/?qa=blob&qa_blobid=10933242674616397781

Answer 2

I am not sure what you mean by the modularity principle or how it relates to repeating preceding steps.

In any case, the analysis group works by avoiding double counting. For example, if you define analysis group A1, then all contributions attributable to A1 that are also included in A5 will be accounted for under A1 when you examine the results. This is why, when you change A5, the results behaves accordingly.

This is also explained toward the end of the following page: https://greendelta.github.io/openLCA2-manual/res_analysis/res_analysis_groups.html?highlight=analysis#new--analysis-groups
 

Therefore, in your case, since you are looping processes with one another, I recommend reading the results from the contribution tree.

Final recommendation: there was a bug in the analysis group feature that has now been fixed in openLCA 2.6. This issue was identified in a former question:https://ask.openlca.org/9846/specific-application-of-analysis-groups