# Adaptability of Buildings: A Critical Review on the Concept Evolution
###### Abstract  
Our ever-evolving built environment is continuously facing emerging needs for housing, work, health, and mobility, among others. Yet, buildings are usually designed and set up as finished permanent objects, reflecting the one constant scenario in mind of defined form, function, and performance. Since change is increasingly inevitable in our life, enlarging buildings' adaptive capacities in response to arising variables and changing conditions over their lifecycle becomes a necessity in seeking global sustainability demands. The concept of building adaptability has been a notable subject in this respect, increasingly stimulating and proposing regenerative alternatives to today's often obsolete buildings. This paper critically reviews the existing body of knowledge on the concept of adaptability in building research. The main focus is made on the evolution of the concept interpretations and related paradigms, and on the development of its applications and strategies in the light of promoting models and trends. Drawing on the literature as a source of evidence, the paper analyzes and classifies the content of existing studies published in scientific journals and gray literature, focusing on a timeframe from 2015 up-to-date. Moreover, the paper aims to build a constructive discussion to identify potential gaps between the actual state of the art and emerging needs, which should be addressed by further research. adaptability; adaptable building; building adaptation; flexibility; open building; shearing layers; building decomposition; circular economy; resilient building +
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uncertainties (e.g., climate predictions, availability of fuel and building materials) [4]. These changes might occur over the lifecycle of a building often irregularly and without being contemplated earlier when the building was initially designed and constructed [5]. Yet, these issues often count on a building's capacity to adapt and keep functioning for a maximum useful lifespan. All bring up the fact that static permanent buildings are no longer an option in our modern life [6]. The concept of adaptable buildings has always been a notable subject in addressing issues of building obsolescence and redundancy. The term \"adaptability\" usually refers to the capacity of buildings to change in response to varying needs. However, the essential value of adaptability comes about--in large part--the impossibility to predict future changes [2]. These changes can be related to social and local factors (e.g., user's preferences, cultural demands, existing materials), environmental motives (e.g., natural hazards, climatic changes such as heat waves), technical requirements and functional performance (e.g., to embrace technological improvements) [7], economic factors, legislative issues (e.g., regulations and policies) [1], stakeholders interests [8], and others [1,4,9]. The theme of building adaptability remains a major interest for scholars and practitioners [10] across multiple disciplines, including architecture, engineering, planning, and management [5], where adaptable buildings are largely perceived as intrinsic to a sustainable built environment [11,12]. This is stemmed from their potential of avoiding premature demolition and preserving the value of materials and embodied energy, together with the costs associated with the production of new materials [2,13]. This also implies the extension of the building useful life since changes can happen while preserving a significant part of a building [4]. Resources scarcity and environmental degradation caused by building-related activities together with the huge investment in refurbishment projects in European countries further emphasize the importance of building adaptability, as it promises to extend the economic viability of buildings and minimizing maintenance costs [4,7]. Furthermore, the adaptive reuse of buildings plays a decisive role in emissions reduction and supports global climate protection [14].