Rethinking Sustainability of Modular Integrated Construction for High-rise Buildings: Dialectics in System Boundaries

Modular integrated construction (MiC) has been adopted in over 100 building projects in Hong Kong. The sustainability of MiC may vary from different socio-technical contexts such as module designs, which however has not been systematically understood. Therefore, this paper aims to systematically examine the sustainability of MiC for high-rise buildings in a dialectical manner. The examination emphasizes systems thinking of MiC from multiple perspectives such as various performance indicators, building types and modular systems, i.e. dialectics in system boundaries. A new concept of total factor sustainability (TFS) is proposed for systematically examining the dialectics of MiC sustainability. TFS is measured in economic, environmental, and social aspects using six key performance indicators. It is comprehensively evaluated using Technique for Order Preference by Similarity to an Ideal Solution. Cross-case studies are conducted using eight representative high-rise building projects to demonstrate and validate the dialectics of MiC TFS. Remarkably, MiC TFS greatly varies from modular system designs, e.g. labor productivity being enhanced by 281% in the case projects adopting double wall systems but only by 138% in the other projects adopting sandwich wall systems. The TFS of MiC building projects could be enhanced by over 60% with more standardized design, easy-to-assemble connections, and enhanced technology maturity. The paper proposes a novel framework of MiC system boundaries for addressing multi-aspect, multi-indicator and cross-boundary TFS analysis, which seeks to understand not only the dialectical sustainability of a single project but also how MiC projects contribute to the whole construction industry. The paper should facilitate more informed decision-making of the government and industry for formulating MiC incentive policies and designing innovative modular systems for enhancing buildings’ sustainability.