A Quality-Dependent Allocation Framework for Open-Loop Recycling in Attributional Life Cycle Assessment

Joanna Pinheiro Rodrigues; Luiz Kulay

doi:10.55845/joce-2026-41319

Authors

Joanna Rodrigues University of São Paulo Author
Luiz Kulay University of São Paulo Author https://orcid.org/0000-0003-1107-1800

DOI:

https://doi.org/10.55845/joce-2026-41319

Keywords:

Open-Loop Recycling, Attributional Life Cycle Assessment, Quality-Dependent Allocation, Circular Economy Modeling, Material Cascading, Environmental Burden Redistribution, Polymer Recycling

Abstract

Open-loop recycling (OLR) is a cornerstone of circular economy strategies but inherently generates multifunctional systems in which materials deliver different functions across successive life cycles. Although attributional Life Cycle Assessment (LCA) provides several allocation approaches to model such systems, only a limited subset explicitly considers material quality variations, and no standardized procedure exists for integrating quality into allocation modeling. This study addresses this gap by developing a quality-dependent allocation framework for open-loop recycling systems within attributional LCA, in which environmental burdens are redistributed according to the functional quality of secondary materials across cascading functions. The method builds on existing allocation principles by introducing refined system boundaries, explicit differentiation between sorting and reprocessing stages, and mass-balance consistency across consecutive functions. Material quality is operationalized through a quantitative scale, and a relative quality index between consecutive product life cycles modulates the fraction of environmental burdens retained within each function and transferred downstream, enabling explicit representation of upcycling and downcycling phenomena. The approach is demonstrated in a four-function polypropylene cascade combining mechanical recycling and energy recovery and evaluated using IPCC 2021 GWP100. Results show that burden redistribution occurs exclusively in the downstream direction and is progressively dampened along the cascade. Variations exceeding 30% in the relative quality index induce changes of approximately 10 – 12% in impacts attributed to intermediate functions, while the aggregated material life-cycle impact remains invariant. Compared with the cut-off method, the proposed framework shifts a substantial share of burdens toward later functions, yielding Global Warming Potential values up to 31% higher downstream without altering total impacts. By explicitly linking material quality evolution to environmental burden redistribution, the proposed framework provides a structured and operational mechanism for representing cascading systems in attributional LCA, offering a conceptually distinct alternative to conventional allocation approaches.

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