Question

How can i justify which general basic uncertainty i enter in the pedigree matrix. I am aware of the ones for the individual categories, such as (reliability,completeness etc.), but I can still enter a general basic uncertainty at the bottom, at least for the Ecoinvent database, I don't know exactly, for example, if I enter the number 20, how I can justify that.

Can you tell me?

for example, if i leave the one in, the standard deviation is very small, which does not make sense to me with the processes i have created myself, but on the other hand, i can't judge at all which number would be better like 20.

Answer 1

ecoinvent has this special table which proposes basic uncertainty for flows:

(from our old project report, https://www.greendelta.com/wp-content/uploads/2017/03/Pedigree_report_final_May2012.pdf)

The newer ecoinvent 3 method report contains the same values but transformed, as the logarithm of these values. The columns refer to the process type, c means combustion, p normal process, a agriculture. It makes some sense I think, but is purely (undocumented!) expert judgement.

Hope this helps, Andreas

Answer 2

Well, basic uncertainty could come from the precision of measuring instruments (e.g. plusminus 5% tolerance), or by using an average of multiple measuring points (be it energy consumption or mass of products). Just a few examples