5. Discussion and conclusion

We presented the method used by Statistics Netherlands to compose an MFM from national statistical data and a case study that demonstrates how indicators can be derived from it. The method contributes to the need for consistent monitoring of material flows in the transition towards a CE. Consistency is achieved by applying statistical principles of the SEEA. The main contribution of this research is the detailed and accessible description of the method of compiling a consistent national MFM database from which CE indicators can be derived. It is important to note, however, that details of the presented method are adjusted when better quality datasets become available or new insights show that the MFM can be improved.

While several countries have experimented with setting up similar systems to the MFM, most notably in the form of physical supply and use tables (see Baud et al., 2011; Kovanda, 2018; Pedersen, 1999), the Netherlands is now one of the few countries that has been developing such a database on a regular basis for over a decade. This has various benefits. Linking existing datasets means that the MFM can be produced consistently on a regular basis which is crucial for monitoring policy effects. For example, this enables the compilation of consistent time series without collecting additional data, and given its consistency with economic accounts it allows for combined environmental-economic assessments (e.g., Pedersen, 1999; Moll and Acosta, 2006; Weisz and Duchin, 2006; Hoekstra and van den Bergh; Pedersen and Deveci, 2014; Kovanda, 2018; Merciai and Schmidt, 2018).

One limitation of the MFM is that the reliability of the most detailed data available cannot be easily verified. The reason for this is that data are collected from sources of varying quality, and often no alternative data sources are available. Therefore the MFM is only published in a relatively aggregated form, and any calculations of indicators at a more detailed level need to be used with caution. So, in addition to the MFM other methods and additional data collection are required to closely monitor material flows in specific sectors or for specific products. The introduction of specific statistical codes for CE-related or bio-based products in classifications would help improve data quality. We also recommend further research to assess and validate the quality of the MFM data on the macro and micro level.

The MFM has become a cornerstone for the development of a Dutch circular economy monitoring framework (see Hanemaaijer et al., 2021). The case study demonstrates that the MFM is a useful tool to extract indicators measuring material flows at the macro-level. The benefit of the MFM is that it provides an overview of all the material flows, ensuring that overall trends in material flows become visible. This is crucial because circular economy policies could lead to shifts in material intensity between sectors and cause rebound effects. In order to monitor the circular economy comprehensively, indicators derived from the MFM should be combined with indicators measuring specific circular economy strategies (e.g., reuse and repair), the reduction of consumption levels and – perhaps most importantly – environmental impacts.

Finally, it is important to realize that similar datasets to those used by Statistics Netherlands are available in other EU countries as they are compulsory under EU regulations. Such detailed data on monetary supply and use tables are often only accessible for national statistical offices. It therefore seems feasible for national statistical offices in other European countries to use a similar approach to develop an MFM. In this context, we encourage collaboration between academic researchers and national statistical offices to develop MFM to improve the quality and comparability of CE indicators in Europe.