Measuring circularity: A (still) ongoing methodological challenge

Time flies by, but almost 7 years ago we published an editorial motivating the discussion on the (at that time) strategic aspects of circular economy and the bioeconomy. In particular, the invitation was to discuss the concept of ‘cascading’, which was a novel concept at the time that intended to evaluate the efforts of the sustainable and strategic utilization of natural resources. Nowadays, the discussion is about ‘circularity,’ which in my opinion is a good development, as it brings into the equation many further facets of the circular systems. However, even after all these years, the discussion is still ongoing, circularity having not been sufficiently defined (and by the way, nor is the definition of cascading!), which has led to conflicting discussions when it comes to evaluating the impacts of new technological concepts. First of all, it is not possible to explicitly evaluate the effectiveness of the ongoing measures to achieve circularity. In addition, different stakeholders have come up with their own definitions based on their experiences, visions, needs and goals, deriving methodological approaches whose results often cannot be compared, making it hard for decision-makers to track progress over time for the ongoing initiatives, or to make comparisons across different sectors and regions, and therefore to have sufficient information to make informed decisions. For this reason, I would like to take two steps back, give an overview of the status quo of the situation, and then identify the current challenges in this field, hoping to move the discussion forward. After several years of development, currently the circular systems such as the circular economy and the bioeconomy are based on several principles such as ‘design for circularity,’ which aims at designing durable, repairable/low maintenance but also recyclable products, and takes into account the whole life cycle of the envisaged products. This same systemic thinking enables fostering implementation of the necessary infrastructure for the material recovery with the aim of establishing resilient ‘closed-loop systems’, another key principle. In addition, the principle of ‘product life extension’ through reuse, maintenance and repair allows keeping the value of the materials within the economic system and minimizing the need for more raw material inputs. Aligned with the material inputs, another principle of utmost importance is ‘resource efficiency’ that aims at minimizing the environmental impacts of products through increasing the overall system efficiency, minimizing waste generation and at the same time fostering the use of renewable resources. A further key principle is the ‘fostering innovation principle’, which considers a systematic perspective and therefore fosters innovation not only in terms of novel technological concepts but also considering innovation in the logistics and services sectors, in the design of products as well as the financing and business models that are applied in the establishment of new – or improved – value chains. Such a principle has led to an expansion of what we considered the circular economy and the bioeconomy systems in terms of the greater diversity of stakeholders that can be identified as characteristics of both of these systems. Finally, taking into account this expansion of the involved stakeholders, ‘collaboration’ could be considered as the last key principle for circular systems. Collaboration now not only in terms of synergic industrial systems but through the involvement of business, (local, regional and national) governments, financing bodies and the different interest groups representing the involved communities. But how is circularity measured, if we do not have a clear definition of circularity itself? Good question. For this purpose, a series of indicators have been developed to evaluate a system’s circularity. Considering the life cycle of a system, we first find input indicators that correlate the amount of resources that enter a system with the efficiency to which these inputs are being used (e.g. materials use, water use, energy use). We then find the output indicators, which correlate the amount of waste that is generated and the rates at which materials within the system are being reused, repaired or recycled. Examples of output indicators are waste generation, material recycling rates (e.g. closed loop recycling) and reuse rates. Finally, we have the impact indicators, which denote a measurement of the environmental, social, and economic impacts of the activities associated to the system. Examples of impact indicators are the carbon and water footprints and economic benefits. In summary, the definitions and the methodological developments have come a long way. However, there are still remaining challenges: In my opinion, the first challenge we face nowadays is the lack of a common definition of circularity. This definition is key to derive a standardized set of ‘circularity indicators’ that can help us measure the effectiveness of technical concepts as they are established in the national and regional infrastructures, or of policy measures that can foster innovation in the circular economy and the bioeconomy fields. We need to address the ambiguity derived from the lack of a circularity definition to ensure collaboration among all involved stakeholders. The second challenge is inherent to the transitional process we are currently experiencing. Both the circular economy’s and the bioeconomy’s political and behavioural frameworks are changing and developing as well, making it difficult for monitoring systems and evaluation methodologies to reflect all these developments. Measuring circularity: A (still) ongoing methodological challenge 1170615WMR0010.1177/0734242X231170615Waste Management & ResearchEditorial editorial2023