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I've created a product system and am currently looking at the climate change impact on the contribution tree and the sankey diagram. On the contribution tree tab it's correctly shown, that the final process contributes to 100% of kg Co2-eq, whereas the Sanken diagram only shows 94.367% (even though the CO2-eq amount is the same in both). 

I have played around with cut-off option of the Sanken Diagram but that doesn't seem to be the issue (no change). 

Pictures of the contribution tree and the sankey diagram are attached. 

I would greatly appreciate any help :) 

 

in openLCA by (120 points)

1 Answer

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by (113k points)
Hi, I cannot read the numbers in the Sankey (!) diagram, the impact analysis results are the same as in the contrubution tree, and the number is also identical in Sankey diagram, impact analysis, and contribution tree? Could it be that you have also negative climate change impacts? Since the contribution tree looks only at one supply chain "branch", if you have two others that contribute + 5.xyz %, and - 5.xyz %, you will receive the same output number in Sankey but the overall contribution of the last process is not 100%?
by (120 points)
Thanks for your answer. I have rerun the whole thing and then it seems to be working. I have found though that (for the Sankey diagram)  if the processes in the first tier behind the final process also have a linkage between each other, the total percentage of that tier doesn't seem to add up (processes that are an input into both those interlinked processes are double counted). That doesn't seem correct to me and doesn't happen in the contribution tree tab - I will therefore rather rely on the information on the contribution tab.
by (113k points)
Well the software does not calculate two times different results unless you change something? Can you please post a picture of the Sankey diagram where you think it is incorrect? Thank you
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