i am using the ProBas database for modelling a die-cast part.
In the database there are many different processes for the production of aluminium.
I used Aluminium-DE-2020_UP and wanted to compare the process with other aluminium processes.
When i create a product system with the Aluminium-DE-2020_UP as the last process and choose add connected processes and connect to the system process, if possible i get a negative GWP (-25kg CO2eq.). When i only select add connected processes i get a very high GWP (5587kg CO2eq.). And when i select nothing of both i get a GWP of 3kg CO2eq.
Do you know what i mean? Why are the results so different?
Can somebody tell me whats the difference between the different selection options and how they relate to the calculation?
Many thanks in advance.