The transition toward a circular built environment brings the component scale to the forefront, redistributing value from the building as a singular object to the elements of which it is composed. Understanding how products are designed, manufactured, sourced, and supported throughout their life cycle therefore becomes essential to enabling this shift. Such a transformation requires a systemic approach that engages all stakeholders within the built environment. Architects and engineers must be equipped to make informed decisions about which products best serve their design intentions in each specific context. At the same time, the building industry must develop the capacity to create truly circular products, responsibly source materials, and align production processes with architectural decision-making. Beyond designers and manufacturers, policymakers, insurers, financial institutions, certification bodies, and users must also reconsider their roles and responsibilities in facilitating the transition to a circular paradigm.This book responds to this urgency by offering a clear and actionable methodology for professionals, researchers, manufacturers, and policymakers committed to advancing circularity in the built environment. The methodology is structured across the four domains of materials, design, manufacturing, and management, and is presented through a series of conversations with designers, makers, and researchers. Core topics include design strategies, material sourcing and recovery loops, stakeholder integration, and the alignment of technical, financial, and regulatory processes.This volume is edited by Olga Ioannou and Ulrich Knaack, two of the late Professor Tillmann Klein's closest collaborators, who laid the foundation for rethinking the component scale as a strategic lever toward a circular built environment. Their direct involvement in circular research initiatives and industry partnerships ensures that the methodologies presented are not only conceptually robust but grounded in real-world application. Through this collaboration, the book reflects a continuity of thought and expertise that has helped shape contemporary discourse on circular building products, offering readers access to a rigorously developed and field-tested body of knowledge.
