# Adaptability of Buildings: A Critical Review on the Concept Evolution
## Content Analysis
### Enablers and Promoting Models
#### 3.3.3 The Circular Economy in Buildings  
Building industry is an important pillar of economy, although also a significant contributor to environmental decline. A direct relationship between environmental problems and climate change on one hand and building-related activities and practices on the other has already been proved and acknowledged by the scientific community, raising issues of resource valorization and environmental impacts' minimization to the top of governments' and scientific society's agendas. The intensified pressure on resources that are becoming increasingly scarce has largely contributed to inflated costs overall and creating uncertainty in the short term [75]. In response to the above issues, the Circular Economy (CE) has emerged as a new paradigm of innovative practice for increased sustainability, aiming at decoupling economic growth from resource consumption [58]. The CE concept proposes a systemic shift from the current linear model of economy (take-make-dispose) by adopting a circular model of close-looped value chains. This concept is becoming more relevant for academia, policymakers, and nongovernment institutions [76; 77]. In this respect, the European Commission (EC) released an action plan to promote the implementation of CE in various sectors at different levels. The CE package of EC considers the building sector as one of the five priority sectors to benefit the CE approach by developing new eco-technologies and circular models for all building-related practices and processes [78]. Rethinking building operations based on circular economy principles promises to help the sector to significantly contribute to the mitigation strategies of climate change by addressing issues of resources efficiency and greenhouse gas emissions reduction that are dominant causes of climate change. This can be achieved by setting new design standards, improving materials, and developing new business-model innovations. Circularity in building is defined as \"the dynamic total of associated processes, materials and stakeholders that accommodate circular flows of building materials and products at optimal rates and utilities\" [79] (p. 261). In order to facilitate change without loss of materials quality, Circular Building (CB) concept requires adaptable buildings [57; 80; 81]. Design for Adaptability (DFA) has therefore been investigated as an important enabler for circularity in buildings, which shed the light on concepts of \"Open Building\" and \"Shearing Layers\". In this respect, [PERSON] [57] affirms that circularity of building products and materials is enabled by adaptable capacity and autonomy over \"fit-out\" configurations. Design for adaptability handles issues of buildings obsolescence and redundancy by employing a lifecycle thinking in order to extend the useful life of buildings and building components. This ideology goes hand-in-hand with CE main strategies of \"closing the loop\" and \"slowing the loop\", sharing the objective of ensuring to minimize consumption of raw resources and energy input, which reduces the environmental footprint of construction activities related to lifecycle stages. Closing the loop assumes intensified reuse and upcycling of components and materials [82], while slowing the loop aims at increasing the longevity and preserve the value, quality, and efficiency of materials and building products [58] to the highest possible extent. The current paradigm of building design and construction proved a fundamental system's deficiency represented in tons of CDW (Construction and Demolition Waste) generated from premature and arbitrary demolition practices [65]. This prevalent end-of-life option for buildings and their components is a result of the linear model of production and consumption in the built environment.