CircularB-DfC: A decision-support tool for prioritizing building design factors to enhance circular material flows

• Introduces CircularB-DfC, a design-stage framework for assessing and prioritising circularity in buildings • Integrates 35 circularity indicators and 20 enabling factors across design and value-chain processes • Provides Delphi-weighted scoring and a practitioner-oriented Excel tool for decision support • Demonstrates framework applicability through three contrasting regional and structural scenarios • Reveals how design strategies and enabling conditions jointly shape circular performance Circularity is increasingly recognised as a critical paradigm for sustainability in the built environment, yet existing efforts to assess it—whether focused on material flow analysis, design-for-disassembly strategies, durability metrics, or carbon accounting—remain fragmented and operate at different scales. Despite numerous indicator sets, the literature lacks an integrated framework that combines both technical design factors and the enabling organisational conditions required to support circular outcomes at the building level. This paper introduces CircularB-DfC (CircularB COST Action – Design for Circularity), a decision-Support Tool with a structured matrix for prioritising building design factors to enhance circular Material flows. The framework consolidates insights from a systematic literature review and a multi-stage expert engagement process, resulting in 35 technical indicators and 20 enabling factors . These are organised into four technical categories: Material Selection; Design for Disassembly; Embodied Energy and Carbon Footprint; Waste Minimisation, and one enabling category, Circular Construction Management, including Governance, Certification, Stakeholder Engagement, Digitalisation, and Socio-economic aspects. Indicators and enablers are aggregated into a Design Score and an Enabler Score to support early decision-making. The tool was applied to three illustrative scenarios: a reinforced-concrete industrial hall in the Western Balkans, a steel office building in Central Europe, and a timber residential project in East London. The steel scenario achieved the highest Design and Enabler Scores, the concrete scenario performed strongest in Waste Minimisation through prefabrication and site-based strategies, and the timber scenario scored lowest overall due to limited reuse and disassembly provisions in the original design. While CircularB-DfC offers a simple and transparent basis for integrating circularity in design, it is limited by the subjectivity of expert-based weighting and its static structure. Future research will focus on dynamic modelling, integration with digital tools, and broader validation to enhance applicability.