Circular building adaptability (CBA) offers substantial benefits to the built environment, including reducing building costs through material efficiency and waste reduction, while enhancing the long-term value of structures through improved flexibility (Hamida et al., 2023). Next to this, CBA contributes to long-term sustainability in the built environment by making it possible to generate new business opportunities within the circular economy (CE). However, the Dutch building industry faces significant challenges in adopting CBA principles, particularly in the context of adaptive reuse (AR) projects. These challenges hinder the industry's transition towards a sustainable and circular built environment.

This research primarily concentrated on testing part of a relatively new framework that links determinants, strategies and the enabling and inhibiting factors of CBA in adaptive reuse projects to support the shift towards a circular economy. Accordingly, this study aimed to answer the following research question: “How can the applicability and effectiveness of design-oriented circular building adaptability strategies (CBASs) be promoted in adaptive reuse projects?”. A stepwise research design of two approaches was followed, namely case studies and Research-through-Design (RtD). The methods include archival research, field observations, semi-structured interviews with key informants, questionnaires, and workshops focused on practical design solutions.

The results indicate that the CBA-AR framework is a useful tool that integrates CBA-determinants, strategies, and associated enabling or inhibiting factors, and can be useful during early-stage planning and collaboration in adaptive reuse projects. Second, based on the findings of the case study, three strategies have been identified as the most applicable and effective, namely: opening the floor plan, providing multi-purpose spaces, and aligning the interconnection between floor plans. In contrast, the less applicable and effective strategies for the cases examined in this study are designing for mixed-use, modularizing spatial configuration, and designing for surplus capacity. Finally, the successful implementation of CBASs requires raising awareness among professionals, as the lack of knowledge often leads to missed opportunities for integrating adaptable and sustainable design strategies.

The scope of the research has been limited to the design-oriented (passive) CBASs, and therefore, directions for future research have been put forward in the conclusion. Moreover, the findings of this study are not generalizable because they are case-specific; however, they provide valuable lessons for future research, policy-making, and practitioners seeking to promote resource efficiency and future-proofing in adaptive reuse projects.