Estimating the impact range of circular economy actions for buildings on basic material demand in the European Union: A combination of qualitative and quantitative approaches

A circular economy in buildings can contribute to reduce the demand for emission-intensive basic materials and thus, to achieve the climate targets of the European Union. However, quantifying the impact on material demand is challenged by the unpredictability of the future. We combined qualitative and quantitative approaches to improve the understanding of such future developments. In detail, expert interviews were conducted to identify influencing factors and to collect estimates for modelling prospective material demand. The results indicate that the adaption is driven by existing and new policies, climate change as well as demographics. This is contrasted by barriers, such as the economic non-viability, the limited availability of substitutes, and the mismatch of supply and demand as well as building regulations. Moreover, the type of influencing factor reflects the maturity of individual strategies related to a circular economy. The estimated impact of circular economy actions on annual material demand for buildings varies between -42 % and +25 % in 2050 compared to a reference development. However, there are not only differences between but also within individual actions. In brief, the maturity of the circular economy actions is reflected by the range of impact on material demand. The novel combination of the qualitative influencing factors and the quantitative modelling results reveals an interrelationship between the drivers and barriers and the impact on material demand. This underlines that the prospective exploitation of these potentials can be actively influenced by adapting the policy framework conditions. This is particularly relevant for less renowned circular economy strategies and actions that are characterized by high potential and high unpredictability. The presented results lay the foundation for a more systematic consideration of material reduction potentials related to a circular economy in prospective scenarios of buildings in the European Union.