Cut-off and impact result accuracy

Question

Hello,

openLCA beginner here.

I'm trying to verify some climate change impact results from the Exiobase 3.4 database. For one certain process, my result are much smaller than the number provided to me. Could this be connected to the cut-off level?

I'm using a cut-off of 1e-10 and receive 0.04164 kg CO2 eq.

For cut-off 1e-7, it is 0.11226 kg CO2 eq.

The 0.11226 kg CO2 eq is very close to what this person has provided me with.

• Are these differences between cut-off levels normal?
• Do the results normally increase or decrease with less cut-off?
• What is the best cut-off level? The one that my computer can still calculate?

Answer 1

normally, the results increase with lower cut-off, so the results you show are a bit surprising. See e.g. the PSILCA pictures were we investigated this a bit:

And for the version comparison in PSILCA:

(both from the PSILCA handbook).

You see that the exact amount depends on the case.

I think that the exiobase version for SimaPro is truncated and somewhat modifiied to allow SimaPro to handle it at all, thus you probably get different results.

What is the best cut-off level?

the lower the better. If you use direct calculation, memory demand is really manageable now with openLCA I think.

Good luck, Andreas