5. Reflections

In this paper, we presented an index decomposition analysis (IDA) of changes in primary abiotic material consumption in the Netherlands. Our main result shows that between 1996 and 2022, substitution, recycling and resource efficiency apparently go hand in hand with dematerialisation over time. These factors were mitigating the upward pressure of economic activity. Only in more recent years, this apparently led to a substantial decrease of primary abiotic resource consumption.

We emphasize that our results must be interpreted carefully. The decomposition analysis does not present a causal link but can uncover correlations. The driver ‘resource efficiency‘ is still subject of research. We aimed to contribute by decomposition analysis of primary abiotic resource consumption in two ways:

• A framework of factors underlying changes in primary abiotic resource consumption:
  There are four factors: substitution of abiotic for biotic materials, recycling, resource efficiency and economic growth. Our aim was to investigate correlations between the change in the resource consumption and the change of the various factors. Quantified contributions cautiously indicate the extent of direct impact of the various factors.
• A long time perspective:
  Our IDA revealed, among other things, that substitution, recycling and resource efficiency apparently go hand in hand with dematerialisation over time. The results show the potential of long time series data for an analysis providing insight in structural changes in substitution, recycling, efficiency, and economy over time.
  
  There are various potential research lines for the future, which are often intertwined:
• Measurement of resource use:
  In Annex A, we already investigated an alternative measurement of resource use, namely input (DMI) instead of consumption (DMC). We might scrutinize further on data and measurement of resource use. Among other things it is important to distinguish re-exports from domestic import and export, and to distinguish food and feed from other biomass, in order to be able to interpret results based on DMC and DMI
• Defining resource efficiency:
  Further, we need to discuss the definition and measurement of ‘resource efficiency’, the ratio ‘total material consumption to GDP’. Do domestic producers indeed use less materials in production, or does the ratio change mainly due to other factors such as economic structural change or a shift to industries abroad?
• Introducing sectoral shift:
  An experimental estimation with an IDA model with a factor measuring sectoral economic shift stumbled upon lack of high quality sectoral data on material use.
• Additional sectoral analysis:
  With high-quality data would be also a valuable addition to insight in material flows and use and the factors underlying these flows and use. Think of, for instance, input-output data on materials used in production chains and footprints.

However, such data improvements are very extensive and bring their own data and measurement issues, whereas we currently just aimed for a first impression of potential relationships in an integral long run framework.