The Potential Contribution of Modular Volumetric Timber Buildings to Circular Construction: A State-of-the-Art Review Based on Literature and 60 Case Studies

When facing the increasing demands of the housing market and balancing the requirements of sustainable development in the construction sector, building design methods should practise material conservation and adopt carbon reduction measures to alleviate the current environmental burden through the implementation of a circular economy approach. Volumetric modular timber design is recognised as a practical application to test the feasibility of a waste-reduced approach. Driven by the aim of further improving volumetric modular timber construction and increasing its use in a circular economy framework, this paper presents a case study review of 60 modular timber building projects constructed using volumetric modules. The dimensions, the architectural and structural design, and the manufacturing and assembly processes of the three-dimensional modular units were assessed to explore their potential for contributing to a circular built environment. The results show that the similarly sized modular volumetric timber units have the potential to serve different functions, and to be reused in subsequent projects. The stacking design allows modular volumetric units to be reused in a way that supports function conversion and satisfies project coordination criteria. The case studies illustrate that modular timber buildings are increasingly used for flexible design solutions, and to meet carbon emission reduction targets. The analysis results can address prevalent misconceptions regarding modular wood construction, provide interested parties with a better understanding, and promote the use of modular volumetric timber units in general.