Differenent Results from GaBi Software and OpenLCA with same Database and LCI-Method

Question

An LCA for a welding process has been performed already with the GaBi software and database and shall now be reimplemented with OpenLCA and the GaBi database (professional SP30).

Unfortunately I obtain different impact category results in the two cases. For example the supplier process "Steel wire rod, production mix, at plant, blast furnace route / electric arc furnace route, 1kg – GLO" has the following impact with the LCI method "CML (baseline) [v4.4, January 2015]".

Eutrophication for 4.2kg material

OpenLCA: 0.00202 kg PO4

GaBi-Software: 0.00161 kg PO4

Where does this difference come from and how can I fix it? I checked the databases in both GaBi and OpenLCA to see if one of them uses for instance an updated process but at least from my perspective they seem to be identical. Also the LCI method is the same.

Answer 1

Hi, for the GaBi databases, it is crucial how the connection was established between processes, since GaBi datasets are quite flexible in how they are connected, in difference to e.g. ecoinvent. In openLCA 1.7, we have therefore introduced new options for making the connection between processes, in a product system, and for GaBi, recommend to not use the autoconnect feature. I guess, therefore, that differences are caused by different connections. Could this be? Thank you,

Andreas

Comments

Yes this could be. I used "Build supply chain -> complete -> Only link default providers". I noticed some input flows are not connected to a process. Some of these (not connected) processes decrease the environmental impact. Finding out which ones are the right ones is quite tideous though.

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Unfortunately I still don't know what provider processes  are needed for the  "Steel Wire Rod" process, so I get the same results as with GaBi. In GaBi it is an aggregated process and doesn't show which providers are used. Is there a way for me to find this out?