# Adaptability of Buildings: A Critical Review on the Concept Evolution
## 4 Discussion and Open Questions  
The utilization of the concept of adaptability in the scope of the built environment usually refers to strategies targeting either (1) designing of new buildings with prospective vision by incorporating adaptability solutions from the early design stages, or (2) redesigning of existing buildings by developing solutions to adapt the existing stock to emerging variables led to their current obsolescence status. The latter case normally considers strategies of retrofitting, rehabilitation, refurbishment, renovations, and adaptive reuse, among others [41; 104]. This categorization of adaptability strategies was made clear through [PERSON] et al. [64] identification of the two adaptability strategies: preconfiguration, which relates to the design stage; and reconfiguration that addresses strategies in the use stage. However, the literature also contains models and decision support tools that address both design and use stages as in [104]. As a matter of evidence, the solutions for enhanced adaptability are more diverse in the case of new constructions than in existing buildings. This is because a large part of adaptability measures and techniques should be thought at the early design stages, then systematically implemented through processes of construction, maintenance, and end-of-life options. Still, some rehabilitation solutions could increase adaptive capacity depending on the scale of intervention and the capacity of the existing building structurally and technically to accept changes. This also depends on the availability of technical data and drawings associated with construction methods and materials applied. Adaptability level in this case is more related to nonstructural elements. In addition, the economic feasibility is in question here. From the discussion presented in this paper, a number of open questions can be suggested to guide potential future research such as:  
1. How can design for adaptability be enhanced in terms of incentives, policies, processes, and stakeholder engagement (process adaptability)? This includes the role of \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Strategy** & **Resilience Feature** & **Values for Adaptability** & **Change** & **Sources** \\ \hline Adaptive skins/shells/envelops (e.g., insulation materials or active renewable elements) & Passive survivability: Refectiveness & Thermal and performance adaptability & Change in performance & [98; 113; 114] \\ \hline Existing infrastructure and structural reinforcement & Robustness & Support future expansions/scalability, e.g., adding stories & Change in size or function & [60; 109] \\ \hline Clear story height & Redundancy; Resourcefulness & Meet floor height requirement of different uses & Change in use & [109; 115; 116] \\ \hline Enclosed courtyards & Passive survivability & Adaptability to environmental conditions & Change in performance & [36] \\ \hline Dynamic facades & Passive survivability; Refectiveness & Adaptability to environmental conditions & Change in use. Change in performance & [117; 118] \\ \hline Active load-bearing elements & Refectiveness; Redundancy & Supporting multiple use scenarios & Change in use & [119] \\ \hline Size and placement of operable windows & Passive survivability & Adaptability to weather conditions & Change in performance & [118] \\ \hline Renewable energies (e.g., solar collectors and photovoltaic panels) & Passive survivability; Redundancy & Adaptability to environmental conditions & Change in performance & [112; 118] \\ \hline Cavity floors & Redundancy; Resourcefulness & Supporting multiple use scenarios & Change in use & [116] \\ \hline Double-glazed and triple-glazed windows & Passive survivability & Adaptability to weather conditions & Change in performance & [86; 112] \\ \hline Green roofs & Passive survivability & Adaptability to environmental conditions & Change in performance & [86] \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Resilience strategies in buildings and their adaptability values.