Residential buildings have become a priority product category for the circular economy agenda in the Netherlands due the large amount of materials that their construction requires, the environmental impact of this demand, and the fact that increasingly more houses are needing to
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Residential buildings have become a priority product category for the circular economy agenda in the Netherlands due the large amount of materials that their construction requires, the environmental impact of this demand, and the fact that increasingly more houses are needing to be built in response to the housing crisis. To guide and monitor the circularity transition for housing, a quantitative understanding of material stocks and flows is needed, together with insight into the potential impact that different circular options could have. This study begins by quantifying the material stocks and flows for residential buildings in the Netherlands in 2019, including material origins and waste treatment flows, by combining data from past studies into an accounting material flow analysis (MFA) model. The environmental impact of the 2019 material demand is also calculated. This quantification of the current state creates a baseline from which circularity and environmental performance for housing can be improved. Desk research is used to create an inventory of options for increasing circularity in the Dutch housing sector, including estimates of the potential and environmental impact of each as can be found in the literature. Modular construction is often mentioned as a circular option for housing due to its industrialized and demountable construction method, which allows for module, component, and material reuse and facilitates building repair, adaptability, and recycling. However, the impact that more modular construction would have on national material flows and circularity has not yet been quantified. Therefore, this study performs a dynamic MFA to investigate how the large-scale adoption of modular construction could influence the material flows for residential buildings in the Netherlands towards 2100. Primary data from two Dutch modular building companies was used as input for the model. The results illustrate that modular construction is an effective narrowing the loop strategy, capable of reducing material demand by 33% in 2030, 40% in 2050, and 60% in 2100, though its reusability benefits remain limited toward 2100 due to the long lifespan of buildings. Ultimately, this study concludes that modular construction, house splitting, transforming existing non-residential buildings into housing, and adding floors on top of existing buildings appear to be the most impactful options for reducing the material input required for residential buildings in the Netherlands and the associated environmental impact.