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Recycling allocation: The cut-off approach
Recycling allocation: The cut-off approach

Use the cut-off allocation approach for modelling recycling with Ecoinvent datasets

Updated over a week ago

Recycling allocation

Recycling a product can be visualised as a multi-output problem. Depending on the chosen allocation methodology the end-of-life (EoL) is allocated in different ways. This has a significant impact on the final LCA results and environmental conclusions.

Recycling seen as a multi-output problem, visualised by Daniel Collado-Ruiz.

The ISO 14044 standard only specifies that a method must be chosen but it leaves it up to the practitioner to select one.

Earthster utilises Ecoinvent's "Allocation, Cut-off by classification" system model datasets. This means that for modelling products with recycled content or recycling processes the cut-off approach should be used to ensure accurate results.

The cut-off approach

The cut-off approach (sometimes referred to as the recycled content approach or the 100:0 approach) accounts for no impacts or avoided impacts beyond the boundary of the product life cycle.

Impacts of primary material production are allocated to the product where the primary material is used. Impacts of the recycling process are allocated to the product where the recycled material is used. Impacts of treatment of waste not recycled are allocated to the product generating the waste. (Hermansson et al., 2022)

Recycling the material at its end of life only credits the product with the avoided impacts of the alternative end of life processes, such as landfilling. (Collado-Ruiz et al.,2011)

Cut off method visualised by Daniel Collado-Ruiz.

Ecoinvent's datasets in Earthster are cut-off by classification

In Earthster all the available Ecoinvent processes are cut-off by classification.

The underlying philosophy behind Ecoinvent's cut-off approach is that primary (first) production of materials is always allocated to the primary user of a material. If a material is recycled, the primary producer does not receive any credit for the provision of any recyclable materials. As a consequence, recyclable materials are available burden-free to recycling processes, and secondary (recycled) materials bear only the impacts of the recycling processes.

For example, recycled paper only bears the impacts of waste paper collection and the recycling process of turning waste paper into recycled paper. It is free of any burdens of the forestry activities and processing required for the primary production of the paper.

And since the impacts of the recycling process are allocated to the product where the recycled material is used, the recycling processes are burden free. This can be seen as empty Ecoinvent processes with no associated environmental impacts (see image below).

Ecoinvent's handling of by-products by classification

The cut-off system model has, broadly speaking, the effect that recyclable materials are cut off at the beginning of the treatment processes, becoming available burden-free for following uses. The treatment of waste is completely allocated to the waste producer, and all valuable by-products of waste treatment are cut off in the waste treatment and become available burden-free. Ordinary by-products are handled by allocation among products if an activity produces more than one product.

Other cut-off approach references:

  • PAS 2050:2011 (British Standards Institute (BSI, 2011))

  • Greenhouse Gas Protocol (World Business Council for Sustainable Development and World Resource Institute (WBCSD &WRI) 2011)

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