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Buildings account for the largest share of accumulated materials and waste globally. Tracking the material composition, quantity and location of these materials, known as building material stock analysis (MSA), is a first step in enabling the reuse or repurposing of materials, key strategies of the circular economy. While the number of building MSAs is growing, there is a need to coalesce methods, data and scope. Therefore, in this work, we reviewed and evaluated 62 journal and conference articles on MSA of buildings from different angles including scope, boundaries, archetype classification, material intensity determination, approaches (i.e. bottom-up, top-down, remote sensing) and quantity of materials to identify barriers, gaps and opportunities in this area along with its implications for decision-making, policy and regulations. We cataloged the three major approaches of MSAs and discuss their advantages and shortcomings. We also created a comprehensive directory of building archetypes, references and materials for future researchers. As expected, most of the studies estimated that concrete had the largest mass compared with other materials; however, mass-based distribution of materials showed significant variations in different building stocks across the world. Also, embedded plastics and their types remain under-represented in current studies. A major barrier to MSA is related to a lack of information on physical attributes and geographic information system, design and construction data. Policy makers can play a role in mitigating data barriers through instituting regulations that enforce the reporting of building-related data during the permitting process. Furthermore, outcomes of building MSA can help policy makers when considering incentives for design and construction that utilize these abundant building materials.

 

As one of the globe's leading sectors for resource use and carbon emissions, the built environment could play a vital role in the circular economy (CE). This study aimed to understand and map the complex systems inherent to CE interventions in the built environment. We conducted a systematic literature review and thematic analysis to identify CE case studies in different cities around the globe that have considered systemic dimensions of CE and their interconnections and iterations. These include governmental, economic, environmental, technological, societal, and behavioral dimensions. The case studies informed a conceptual model that illustrates how CE functions in an urban setting. The model represents the interdependencies, flows, feedbacks, and unintended consequences that may result from the interaction between the CE research dimensions in cities. We hope to help policymakers, designers, and researchers to better understand how CE functions in urban settings, and to ethically design changes in the system to achieve circularity goals. The results suggest that meaningful stakeholder engagement is key to co-designing ethical CE interventions in the built environment. Finally, engaging disciplines like economics and decision sciences, and better understanding the role of public policies and human behavior are vital to future CE interventions in urban settings.