The circular economy has long been regarded as a key strategy for achieving sustainable development and has more recently been recognized as an effective approach to crisis response. This study contributes to this nascent literature by introducing a dual hierarchy of 6Rs strategies as a guiding framework for circular post-disaster recovery to support the integration of circularity into the United Nations' “Build Back Better” approach. The novelty of the proposed hierarchy lies in the two-vector operationalization of each strategy, considering both past and future perspectives. This dual focus facilitates the recovery of materials and components from disaster-affected buildings, the restoration of damaged structures, and the design of new buildings with a stronger emphasis on circularity. Based on the hierarchy, a typology of design strategies for circular recovery and reconstruction has been proposed, structured around four key features, offering practical guidance on how different aspects of circularity can be operationalized in rebuilding efforts. In addition, the study outlines methodological recommendations for assessing the circularity potential of damaged structures, a critical step in planning adaptive and resource-efficient rebuilding. The article also examines the case of war-torn Ukraine as one of the most devastating man-made disasters today. The potential for Ukraine's circular recovery within the framework of global and European Union disaster management mechanisms, as well as the European Commission's policies in the construction industry, has been explored. The study employs a three-step multi-method approach that includes a literature review, critical analysis, and conceptual modeling. Key findings, comprising a dual hierarchy of strategies, a typology of design approaches, and recommendations for circularity assessment, contribute to advancing circular recovery and reconstruction after disasters in various contexts, including war-torn Ukraine, and reflect their practical significance for circular recovery initiatives.

This paper provides a holistic overview of the evolution of policies towards digitalising energy renovation processes in the European Union (EU). Since the European Green Deal initiative in 2019, EU policies have been increasingly addressing the digitalisation of the building industry to enable evidence-based decisions when tackling environmental challenges. To better understand the development(s) since, this paper integrates a structured policy analysis approach and critically reviews 31 EU policy documents on digitalisation and/or energy renovation. The analysis identified a growing number of policy instruments aimed at supporting a robust use of data, to, among others, improve decision-making and information sharing throughout the energy renovation process. These include Energy Performance Certificate, Building Renovation Passport, Smart Readiness Indicators, Level(s), Digital Building Logbook, Digital Product Passport, Digital Twin, Building Information Modelling, and Digital Permitting. While each of these nine instruments can independently facilitate decision-making on sustainable and/or smart renovations, they also project a significant degree of complementarity between each other. To that, this paper presents the Digital Energy Renovation Framework, which comprehensively synthesises the (inter)relationships between the proposed policy instruments with respect to facilitating energy renovation processes. A key finding is that the integration between the Building Renovation Passport and a data-rich Digital Building Logbook is fundamental to maximise the impact on decision-making throughout the renovation process. To achieve this, ensuring coherence and interoperability of data throughout the renovation value chain is crucial, with the standardisation of data formats and protocols being essential for effective data gathering and processing across these instruments.

The concept of Circular Economy (CE) has emerged as a promising alternative to the current linear economy, decoupling economic activity from the depletion of natural resources and promoting a restorative and regenerative system. The transition of the building industry to a circular one can be achieved through four core resource principles: Narrow (minimising the use of primary resources), slow (extending the lifetime of buildings and products), close (regaining post-use and construction waste through reuse or recycling), and regenerate (minimising toxic substances and maximising the use of renewable resources). These principles provide a framework for exploring the role of digitalisation in the transition of social housing organisations (SHOs) toward circular housing practices, with a focus on European SHOs, particularly those in the Netherlands. This thesis follows a structured format comprising six chapters, with four of them encapsulating the author’s published articles. Chapter 1 serves as the introduction, providing a contextual foundation for the research. It outlines the overarching theme of the thesis, which revolves around the intersection of CE, digitalisation, and the built environment, with a specific focus on SHOs. The chapter sets the stage by identifying the gaps in existing literature, emphasising the need for a comprehensive conceptualisation of this emerging research field. It further delves into essential methodological aspects, the problem statement, and the broader significance of the research. In Chapter 2, the research delves into an exploration of the current state of CE implementation in Dutch SHOs and provides insights into the pressing barriers, and potential enablers. A Delphi study conducted with 21 social housing professionals reveals that, as of 2020, SHOs were in an experimental phase, incorporating circular construction techniques in pilot projects. Barriers encompass organisational priorities, operating within a linear system, and a lack of awareness. Also, financial challenges related to the costs of circular materials also emerge as significant hurdles. Chapter 3 develops a framework, the Circular Digital Built Environment Framework, in an exploratory qualitative research approach. This conceptual model integrates CE principles with digital technologies to provide an understanding of their potential applications within the built environment. The framework is constructed through expert workshops, literature reviews, and evaluations of current research and practices, resulting in the identification of over ten key digital technologies. These technologies encompass a broad spectrum, including big data analytics, blockchain technology, and material passports. The framework not only informs subsequent empirical studies but also serves as a valuable guide for scholars and industry practitioners navigating the intersection of digitalisation and circularity in the building industry. Chapter 4 presents an analysis of how enabling digital technologies, identified in Chapter 3, are practically employed in real-life practices, specifically within circular new build, renovation, maintenance, and demolition projects of forerunner Dutch SHOs. Employing a multiple-case study approach, the chapter gathers empirical evidence from three large-scale SHOs through semi-structured interviews, desk research, and extensive data analysis. The within-case and cross-case analyses reveal insights into the types of digital technologies being deployed, their impact on circular practices, and the challenges encountered in their adoption. By examining the real-world examples, Chapter 4 contributes to the evolving domain of digitalisation for a circular building industry. Chapter 5 addresses the challenges associated with data (identified in Chapter 4), with a specific focus on material passports as a crucial tool for circularity in existing housing stock. Employing a multiphase mixed-method research design, the chapter utilises the SCOPIS method (Supply Chain-Oriented Process to Identify Stakeholders) for user and data mapping. This approach results in a data template outlining the requirements of users for material passports. Subsequently, the study tests this template through a case study, identifying critical data gaps and proposing a material passports framework to address these gaps. By leveraging both digital technologies and human expertise, Chapter 5 offers solutions to enhance data management in the pursuit of circularity within the building industry. The findings contribute to ongoing industry and policy initiatives. Chapter 6, the concluding chapter, consolidates the exploration conducted throughout the thesis. It presents the overarching contributions of the research, offering a summary of the scientific and practice contributions and recommendations derived from the entire study.

The application of the circular economy (CE) in the building industry is critical for achieving the carbon reduction goals defined in the Paris Agreement and is increasingly promoted through European policies. In recent years, CE strategies have been applied and tested in numerous building projects in practice. However, insights into their application and decarbonisation potential are limited. This study analysed and visualised 65 novel real-world cases of new build, renovation, and demolition projects in Europe compiled from academic and grey literature. Cases were analysed regarding the circular solution applied, level of application in buildings, and decarbonisation potential reported, making this study one of the first comprehensive studies on the application and decarbonisation potential of circular strategies in the building industry in practice. The identified challenges of using LCA for CE assessment in buildings are discussed and methodological approaches for future research are suggested.

Passports for circularity, e.g., digital product passports and material passports (MPs), have gained recognition as essential policy instruments for the Circular Economy goals of the European Union. Despite the growing number of approaches, there is a lack of knowledge about the data requirements and availabilities to create MPs for existing buildings. By deploying a mixed-method research design, this study identified the potential users and their data needs within the context of European social housing organisations. Three rounds of validation interviews with a total of 38 participants were conducted to create a data template for an MP covering maintenance, renovation, and demolition stages. This data template was then tested in a case study from the Netherlands to determine critical data gaps in creating MPs, including, but not limited to the composition of materials, presence of toxic or hazardous contents, condition assessment, and reuse and recycling potential of a product. Finally, an MP framework is proposed to address these data gaps by utilising the capabilities of enabling digital technologies (e.g., artificial intelligence and scanning systems) and supportive knowledge of human actors. This framework supports further research and innovation in data provision in creating MPs to narrow, slow, close, and regenerate the loops.