How to calculate the GWP-GHG indicator when using OpenLCA and 15804 A2 2020 impact assessment methods

Question

Hello.

I am using the EuGeos impact assessment method of 15804 A2 2020 through OpenLCA to calculate the necessary environmental impacts for a construction product EPD.

According to PCR:2019 for construction products I have to also calculate GWP-GHG indicator. The impact assessment method contains the following GWP indicators:

1. GWP CO2 outake
2. GWP biogenic
3. GWP fossil
4. GWP land transformation
5. GWP total

I have surmised after some research that in order to calculate the GWP-GHG, the formula is either GWP total - GWP biogenic = GWP - GHG or GWP total - GWP biogenic - GWP COW uptake = GWP-GHG, but I am not sure.

Can you help me with this issue? Is one of the above formulas or I have to follow another one?

Answer 1

Hello Giannis,
To calculate the GWP-GHG using the EN 15804 +A2 add on for ecoinvent 3.9.1, you simply need to go to the impact category of "GWP-biogenic" then go to characterization factor, then set the carbon dioxide factors to 0.

Answer 2

I want to add that instead of subtracting one category from another, you can also copy and paste the GWP-total to create a new category and rename it to GWP-GHG. Then you go inside the characterization factors table and you remove (or you set to zero) the biogenic carbon dioxide flows like "Carbon dioxide, non-fossil, the "Carbon dioxide, non-fossil, resource correction" if it exists, and the carbon uptake flows like "Carbon dioxide, in air". This would give you the GWP-GHG from PCR 2019:14 compared to the GWP-total from EN15804+A2.

Surprisingly the PCR 2019:14 does not change "methane, non-fossil" back to "27.0", so the characterization factor for biogenic methane stays as it is in EN15804+A2. If there would be the biogenic correction for methane, too, the GWP-GHG would be simply the same as GWP-total in EF 3.1 (not the EN15804 version).