Timber, as a renewable material, could reduce reliance on conventional construction materials such as reinforced concrete, thereby lowering carbon emissions. Its light weight, structural reliability, and efficiency in on-site assembly make it well suited to modular systems, which benefit from standardized components in both smaller- and larger-scale projects. However, existing research related to timber construction often emphasizes specific technical or performance issues, while systematic investigation of the timber module as a core building unit remains limited. This study adopts a multi-layered framework for circular modular timber construction, integrating design, structural, prefabrication and reuse perspectives to investigate timber modules, where each layer builds upon and interacts with the others. Through selected cases, the analysis characterizes how modules of different scales and forms are generated to meet spatial and functional needs, and highlights how prefabricated units support more optimized manufacturing. Furthermore, circular design principles are reinforced through reversible joints and design-for-disassembly techniques. The main findings highlight the proposed framework that positions modular units as central to design and construction, contributing to adaptable configurations and the reuse of timber components. Potential future research directions are highlighted, including the incorporation of quantitative evaluation indicators to support the assessment and implementation of circular design strategies.
Zhang et al. (Mon,) studied this question.