**3.4 Reversible building design**

Design for adaptability and flexibility is also known as reversible building design or transformable building design. Design for reversibility supports multiple resource life cycles by integrating other strategies, which includes the design for adaptation, modularity, standardization, prefabrication, disassembly, up-cyclability and adjustment, and flexibility [45]. According to Durmisevic [46], reversible building design protocol on resource circulation covers three main dimensions: functional (spatial), technical (structure), and esthetic (physical) alongside their associated design indicators. Functional reversibility is a design dimension that involves the change of use of space into another without recourse to further material or component use. Technical reversibility is concerned with the design approach that transforms the whole or parts of a building through the rearrangement of the structural components [45]. Design error has been identified as the major barrier to reversibility.

Design for flexibility can facilitate easy refurbishment in the housing sector to avoid untimely demolition through adaptation and material recirculation potentials at building end-of-Life (EoL), and building lifetime extension [47]. Through reversible building design in the housing sector, it can lead to high-value retention in the environment. A study established that reversible design can lead to a 14% reduction in greenhouse gas emission, which corresponds to 1740 t CO2-eq for building components, such as structural elements, foundation, and ceiling components, as evidenced in the study carried out by Kröhnert [47]. Similarly, Kröhnert [47] investigated the adoption of reversible building design principles in multi-story residence building components, which resulted in a reduction in embodied GHG emission, improvement in re-cyclability and re-usability of components, and retention of environmental value.
