The authors used eight criteria (transparency, stakeholder engagement, effective communication, ability to track temporal changes, applicability, alignment with CE principles, validity and relevance to sustainable development) in their frameworks assessment. Additionally, they defined 12 validity requirements to assess to what extent the indicators in the frameworks reflect CE aspects.
The assessment reveals a wide variation regarding the extent to which the frameworks match the criteria with none of them satisfying all. In addition, in terms of validity criterion, none includes indicators that fulfill all the validity requirements. Furthermore, most frameworks consist mainly of environmental indicators and only three include indicators reflecting aspects related to the four pillars of sustainable development (environmental, social, economic and governance). Further research could develop a standardized framework for measuring circularity at the city-level and improving existing frameworks.