Circular Economy Strategies in the Historic Built Environment: Cultural Heritage Adaptive Reuse

Circular Economy (CE) is currently promoted through policy, urban and regional strategies as well as emerging as a relevant research sector. Within this context, circularity in the built environment is attracting attention with applications in many design and urban projects. The general principles of CE are applied to existing and new buildings, focusing on the "end-of-life" stage and developing sustainable innovative solutions to optimize dismantling and reuse of materials and technological parts of buildings. However, in historic urban areas the principles of dismantling and reuse of materials remain barely applicable (end-of-life), as well as the application of standard renewable energy systems (usage), due to cultural heritage unique characteristics and heritage regulations oriented to its preservation, conservation and transmission to future generations. As a consequence, adaptive reuse of cultural heritage seems to be the one of the most viable solution to apply CE in the historic built environment. In this article, we aim to identify CE solutions and to lay the foundation for the future development of a system of indicators able to support circular adaptive reuse choices in the historic built environment. The starting point is the Horizon 2020 "CLIC" project (Circular models Leveraging Investments in Cultural heritage adaptive reuse), which focuses on adaptive reuse as a key strategy for CE implementation in historic cities and regions. The concepts of Circular Economy, Circular Built Environment and Circular Urban Metabolism are explored. Under these perspectives, three representative case studies are described: the first is "De Ceuvel" project in Amsterdam, a second application at a different scale is referred to "Rehafutur Engineer's House project" (France), and finally, the circular adaptive reuse of a rural village in Spain, within the "ReDock project" in the Altiplano region in Spain, is explored. Conclusions highlight the need of suitable indicators synthesizing theory and practice of CE in historic built environment, starting from the recognition of multiple impacts of cultural heritage adaptive reuse practices.