Why do I get negative results in all impact categories?

Question

I am using openLCA 1.10.3 and the ELCD and EF databases. For my thesis I want to do an LCA on the production of a wood plastic composite. When I let openLCA run calculations on my product system I get all negative results, and I don't know why.

I will attach a picture of my product system and the results I am getting.

This is maybe a stupid question but am I supposed to calculate the impact of the electricity used for example for the extruder process myself and then enter the outputs (e.g. CO2 emissions) into the process? I thought openLCA would do that based on the default provider of the flow?

Answer 1

Did you create the life cycle model manually or automatically? Product system using the EF and the ELCD database should not be created with autoconnect since the processes contain, due to a limitation of the GaBi software, products on the input side e.g. that will then be followed by openLCA in the autoconnect routine, although the processes are meant to be fully terminated system processes.

Hth, Andreas

Comments

thanks for your reply! I did create it manually at first but then selected "right click - complete supply chain" for all the individual processes. Was I not supposed to do that?

I've never worked with openLCA before and I find it a bit confusing tbh.

---

the "complete supply chain" is the same as automatic connection of processes. "I find it a bit confusing" - maybe if you are used to a different LCA software?

---

So I recreated the system model without auto-connecting the processes and IT WORKED!! thank you very much for your help :)