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I have observed the impacts of some processes shown in the 'Process results /impacts assessment results tab, Upstream incl direct column', are not identical to the impact of the same processes shown in the contribution tree tab.

See in the e.g. below the EI acidification impact of the process 'Product manufacturing' in 'process results' vs 'contribution tree' tabs.

Key info : I have noted the issue appear only when there are loops in the modeled process.

Other key info: it's very important the 'Process results /impacts assessment results tab, Upstream incl direct column' be the correct (as well, I mean despite of the loops) as there are the values that are exported to Excel in the "process upstream impacts" sheet, and I work with to built my EPD.  Indeed, as mentioned in another discussion of this forum, the export function from the "contribution tree" tab can only export one impact category at the time - which means that it needs to be repeated for all impact categories.

The sheet "process upstream impacts" in the Excel sheet exported allowed you to easily rebuilt the contribution of n-1 inputs on every impact categories, which is essential when you use the software to do EPDs.

Thank you very much for your feed back !

Kind regards


in openLCA by (120 points)

1 Answer

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by (114k points)
Hi Marion,

so indeed, the process results show the entire results for a given process, the contribution tree only results for a process in one branch in the life cycle system, and since a process can be used several times, this will not necessarily be the entire impacts for this process.

All the best,


- I would recommend to migrate to openLCA 2.1 ;)