Quantifying building adaptability and circular performance through BIM: the adaptation intensity index (AII), circular adaptability performance (CAP), and digital adaptability passport (DAP)

Purpose Building adaptability is increasingly recognised as a critical strategy for enabling circular and low-carbon transitions in the built environment. However, it remains largely conceptual, lacking quantifiable representation within digital design workflows and systematic integration with performance assessment frameworks. This study aims to operationalise building adaptability as a measurable and digitally embedded attribute within Building Information Modelling (BIM) environments and to establish a structured linkage between adaptability parameters and circular performance outcomes. Design/methodology/approach This study adopts a Design Science Research (DSR) methodology combining literature synthesis, expert consultation, computational implementation within an IFC-based BIM environment, and case study validation. The research develops and integrates three artefacts: the Adaptation Intensity Index (AII), the Circular Adaptability Performance (CAP) metric, and the Digital Adaptability Passport (DAP). Findings The findings demonstrate that building adaptability can be systematically quantified and integrated within BIM-based workflows. The proposed framework establishes a structured linkage between adaptability assessment and circular performance evaluation, while introducing a digital governance mechanism that enables structured management and traceability of adaptability-related information. Research limitations/implications This study is limited by its application to a single case-study building and a controlled BIM environment, which constrains the generalizability of weighting factors and reference values across building typologies. Adaptability scores rely partly on expert judgement and available design-stage information, which may evolve during operation. Despite these limitations, the research provides a transferable framework for integrating adaptability into BIM-based circular performance assessment and establishes a foundation for future automation, broader typological validation, and integration with digital twins and lifecycle assessment workflows. Practical implications The framework provides practitioners with a structured method to assess building adaptability as a measurable performance criterion within BIM-based workflows. By embedding adaptability and circularity indicators in open BIM standards, it supports comparison of design alternatives, documentation of future change potential, and informed decision-making across project phases. The Digital Adaptability Passport enables continuity of adaptability data beyond design into operation and renovation. Future development will focus on integrating the framework into BIM tools to automate adaptability assessment, allowing adaptability to be evaluated continuously as building designs evolve. Social implications By enabling buildings to adapt over time rather than become obsolete, the proposed framework supports more resilient, inclusive, and long-lasting built environments. Quantifying adaptability helps align design decisions with changing user needs, evolving social functions, and long-term community use. Improved documentation and governance of adaptability information also enhance transparency and accountability among stakeholders, facilitating informed participation across the building lifecycle. In the long term, promoting adaptable and circular buildings can contribute to reduced disruption from renovations, extended building usability, and more sustainable use of resources within communities. Originality/value The study integrates quantitative adaptability measurement, circular performance assessment and IFC-based governance within a unified digital framework, strengthening the link between design intention and lifecycle sustainability performance.