# Adaptability of Buildings: A Critical Review on the Concept Evolution
## Content Analysis
### Enablers and Promoting Models
#### 3.3.2 Shearing Layers and Building Decomposition
They proposed a hierarchy of four functional levels of building composition on material level (Building, System, Component, and Element) among which flexible connections should exist to facilitate change. Disassembles happen on building level to separate systems, then on system level to separate components, and finally on component level to separate elements and materials. Another decomposition method was introduced by [PERSON] and [PERSON] [71] who proposed categorizing products into platform-based families in order to standardize the arrangement of subsystems within a system layout. By doing so, they suggest dealing with classification of system and subsystem characteristics rather a component-level categorization. The approach supports an efficient and flexible positioning of products in companies, meanwhile it substantially decreases a system's complexity and improves its configurability. This happens by defining multiple hierarchical layers of product architecture. The layers are then to be used for identification of differentiation needs and commonality potential within each product family, taking into account market data and design dependencies. A similar approach was introduced by [PERSON] et al. [72]. Again, [PERSON] et al. [73] proposed two components classification schemes for identification of components for designing product variants and freeze planning. The suggested schemes rely on components connectivity and change risk evaluation to calculate a product likelihood of change and the impact resulting from that change in terms of the feasibility of reproducing the component to be changed. The resulting values are used to compute the common risks between components by considering indirect change propagation. [PERSON] et al. [30; 39; 54] focused on addressing the effects of particular components and subsystems on the capacity of transformation and reconfiguration of a building during its lifespan. The authors investigated the way components are clustered and the level of dependency between components of varying lifespan. They emphasized the role of identifying the types, boundaries, and configurations of relationships as a critical component for minimizing the implications of change. Moreover, the authors proposed to employ the DSM method (Design Structure Matrix) that incorporates the two concepts of decomposition and dependencies, and delivers quantitative results. Building components are first categorized into Brand's layers in order to understand the interrelations between them. Then, potential reorganization of the components through clustering is examined. This methodology gives insights into the appropriate layer placement of components and possibilities of introducing new layers, bearing in mind to address the undesired dependencies [54]. Ensuring independence when integrating systems or layers within a building is also highlighted in the literature as a key principle of adaptability that allows components to be removed, replaced, or upgraded without influencing the efficiency of the adjacent systems [3]. In this respect, [PERSON] [57] emphasized on providing a clear identification of the components and materials consisting each of the shearing layers while paying a high attention to the intersection zones where demountable and reversible solutions must be contemplated. Recent decomposition methods propose innovative and efficient strategies that employ the utilization of BIM (Building Information Modelling) and automated tools. [PERSON] et al. [67] developed software to apply a graph-based decomposition methodology of design into nonrepetitive modules containing components of similar life spans. The methodology then uses a clustering algorithm that is able to interpret BIM data to define an optimal assembly of modules taking into account a minimum connectivity among components. The scholars suggest that standardizing certain interfaces between assemblies of elements allows interchangeability and accurate fit rather than when standardizing the assemblies themselves.