Hi,
I’m using the EF 3.1 database and I am modelling the EoL of a product, which includes recycling of cardboard and plastic, and incineration of the percentage that’s not recycled of those components and of wood. I intent to use the opposite direction approach to model waste. I modelled the recycling processes as inputs with positive values and the incineration processes as outputs with positive values. I didn't use the auto-link function to create the product systems.
However, I think I did something wrong because the results of the impact analysis show negative values for acidification, ecotoxicity, EF-particular matter, etc.
The images show inputs/outputs of the process, the model graph of the product system, and the results of the impact analysis.
![](https://ask.openlca.org/?qa=blob&qa_blobid=8050364403041628064)
![](https://ask.openlca.org/?qa=blob&qa_blobid=9008926433508373485)
![](https://ask.openlca.org/?qa=blob&qa_blobid=8328983462859693635)
Should I have modelled the process differently (i.e. inputs and/or outputs and absolute values)? Or are the negative results okay?
I appreciate any help I can get.
Thank you. Regards,
Elli