Interim tandems of life cycle assessment methods and circularity indicators—elaboration for the circular bio-economy

Introduction The transition toward a circular economy (CE) is a key strategy for sustainable production and consumption, yet its contribution to sustainability depends on how it is assessed. Life Cycle Assessment (LCA) provides a robust framework for quantifying environmental impacts, but challenges arise when modeling circularity strategies such as recycling, recovery, and reuse. These include material quality degradation, allocation across successive uses, and capturing open-loop or cascading use patterns common in bio-based materials, which are modeled differently by different LCA methods. To address these challenges, this paper examines if and how circularity indicators (CIs) can complement LCA methods, with particular focus on the bioeconomy. Methods First, we review aspects and coverage of 48 identified circularity strategies for six prominent LCA methods—Product Environmental Footprint (PEF), EN 15804, Allocation at the Point of Substitution (APOS), and Consequential LCA (CLCA), and two system expansion approaches—alongside three stand-alone indicators: the Material Circularity Indicator (MCI), Circular Transition Indicators (CTI), and ISO 59020:2024. Using natural fiber insulation as a case study, we demonstrate the strengths and limitations of different LCA approaches. Results and discussion Results show that coverage of the 48 circularity strategies varies substantially among these LCA methods (13–42 covered) and CIs (9–22 covered). CLCA addresses the most circularity strategies (42). There are only five circularity strategies that are not covered by LCA, including those with socio-economic implications, which an improved life-cycle sustainability assessment framework could eventually address. In those five cases, the CIs CTI, and ISO 59020:2024 may be applied as a complement to LCA on an ad interim basis. A framework is proposed to select combined sets of LCA methods and CIs for specific goals and scopes.