Primary Energy Indicators Calculation ecoinvent EN 15804

Question

Hello,

I have a question about calculating the primary energy use indicators using the ecoinvent EN15804 add-on. In my assessment, the resulting values for PERM, PERE, PENRM and PENRE calculated by the software do not make sense. For example, PENRM has a value greater than zero even though it is for a wood material, and the values for PERM and PENRM differ significantly from my own calculations using the LHV. Therefore, I would like to understand the calculation process behind these figures in the software. Also, do I need to calculate the primary energy indicators separately again, or is it even necessary to use the cumulative energy demand method?

Thank you in advance!

Answer 1

Which Nexus version of the EN15804 add-on are you using? In the last versions, according to the PCR, we set PERM/PENRM to zero by default from the background database, and it is PERE = PERT - PERM and PENRE = PERT - PERM.

You can also see how it is calculated when you click inside these impact categories. PERT and PENRT are always calculated from the cumulative energy demands of renewable energies (PERT) and non-renewable energies (PENRT), taking into account the lower heating values. PERE and PENRE are calculated automatically as a substraction of the total and the material use, so there is no need to model this.

The only thing you have to model by yourself (unfortunately demanded by the PCR, even though not being a real "primary energy") is PERM and PENRM with the net calorific values (lower heating values) of your product inputs. If you do not explicitly model these indicators in your own foreground, PERM and PENRM will be zero by default, and it will be PERE = PERT and PENRE = PENRT. When you place the indicators for PERM and PENRM into your own foreground models with the right net calorific values, you will see that these values will automatically count towards PERM, PENRM and that PERE, PENRE will be adjusted accordingly. The total values will stay as they are, since they are correct "real" life cycle indicators for the primary energy demands that stem from elementary exchanges with the environment like coal, gas, oil etc.

Comments

Thank you very much for your answer.  I'm using the EN15804 add-on to ecoinvent v3.10.

I understand your reply and that I have to model PERM and PENRM myself in the foregroudn data. But I still wonder why the values for PERM and PENRM are not 0 in my case, even though I haven’t made any manual adjustments and modelling yet. Could this be because I’m not using the latest database version?

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You are right, we changed this in the newer versions to reflect common practice in EPDs.

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Thank you for your answer.
Is there a possibility to still model this correctly for the use in an EPD in the software version that I use? How can I change the values for PERM and PENRMim the software to the correct values that I calculated with the lower heating values of the Materials?

Thank you in advance.

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ok, just delete the ones the software provides and calculate them manually for the foreground. Personally, as engineer, I think this is not a perfect solution but this is current generally accepted practice given that for system processes that you have also in ecoinvent unit process databases, a correct calculation is not possible for these indicators, and a common agreement (which I tried to address in the earlier versions of the EN database) is not really in reach. So we gave up here, basically...