Quality in the circular economy: What does it mean, and how is it measured?

Abstract

Quality is increasingly recognized as a critical factor for achieving functional value retention in the circular economy. However, the concept remains poorly defined and inconsistently measured, limiting its integration into circularity assessments. This article develops a typology that distinguishes six types of quality metrics based on two dimensions: the targeted resource state (material, component, or product) and the nature of the quality characteristics assessed (intrinsic or extrinsic). It also identifies three assessment levels (generic, application-specific, and indirect) reflecting how quality is evaluated in practice. To illustrate the typology, existing approaches that quantify changes in resource quality were collected and positioned within the typology. This analysis highlights the diversity of methodological strategies and provides guidance on when to use which type of metric. While no single metric can fully capture the multifaceted nature of resource quality, the typology provides a practical foundation for more consistent quality assessments in circular economy research