Dr Jackie Yang
Senior Lecturer in Quantity Surveying
School of the Built Environment
Publications
Journal articles
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Yang Y, Luk C, Zheng B, Hu Y, Chan AP-C, 'Disassembly and reuse of demountable modular building systems'
Journal of Management in Engineering 41 (1) (2024)
ISSN: 0742-597X eISSN: 1943-5479AbstractPublished here Open Access on RADARNumerous efforts have been exerted to explore how modular building systems are built. But limited research has focused on how modular building systems are deconstructed. Deconstruction is a means to systematically disassemble buildings and prioritize building reuse. This paper aims to understand the deconstruction process of modular building systems by providing empirical insights into the disassembly and reuse processes. To achieve this goal, this study employed a mixed-research method, incorporating ethnographic site observations, semistructured interviews, and archival research, through a case study of a four-story demountable modular building. The empirical findings indicate that the disassembly process consists of a hybrid sequential and parallel disassembly of modular units, whereas the reuse process consists of four subprocesses: take-back, material tracking, quality inspection, and touch-ups. The contribution of this study to the body of knowledge on deconstruction is twofold: (1) design for deconstruction does not inherently ensure effortless ease of disassembly; and (2) factors such as client ownership, digital material tracking, and ease of value retention play crucial roles in facilitating building reuse. These findings enhance the understanding of the deconstruction process by addressing the gaps in procurement, information, and quality between the disassembly (the first use cycle) and reuse phases (the second use cycle). By exploring disassembly sequence, take-back mechanisms, technology-driven traceability, and value retention processes, this paper provides valuable support to practitioners transitioning toward the reuse of modular buildings.
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Yang Y, Zheng B, Luk C, Yuen K, Chan A, 'Towards a sustainable circular economy: Understanding the environmental credits and loads of reusing modular building components from a multi-use cycle perspective'
Sustainable Production and Consumption 46 (2024) pp.543-558
eISSN: 2352-5509AbstractProperly designed modular construction offers the potential for easy disassembly, relocation, and reuse across multiple use cycles. However, the environmental benefits and burdens resulting from the reuse of modular components over these cycles are not well understood. The study aimed to assess the environmental credits and loads associated with reusing modular components over multiple use cycles. This aim was achieved through two approaches. Firstly, three dedicated life cycle assessment (LCA) allocation rules were adopted, namely, cut-off with Module D, the Product Environmental Footprint (PEF), and the Circular Footprint Formula (CFF), to evaluate the environmental impacts of production, reuse, repair, replacement, recycling, and disposal of a modular unit (including the steel frame, concrete slab, and steel connector) across different life cycle stages (Module A, Module C, and Module D) and use cycles (first, intermediate, and last). The PEF approach was determined to be the most suitable for interpreting the environmental credits and burdens associated with reuse. The study found that the reuse and recycling of the modular unit resulted in approximately 9007 ± 362 kg, 2925 ± 602 kg, and 8433 ± 544 kg of equivalent carbon dioxide emissions in the first, intermediate, and last use cycles, respectively. Secondly, a global sensitivity analysis was performed to assess how uncertain input parameters related to future use cycles (e.g., reuse rate, direct reusability rate, recyclability rate, and transport distance) influenced the LCA outcomes. The results revealed that it is beneficial to achieve a higher level of reusability (i.e., direct reusability) and recyclability for the steel frame to maximize the environmental advantages. The impact associated with a relatively lower level of reusability (i.e., repairable) and recyclability for subcomponents is considered environmentally acceptable. However, the lowest level of reusability of subcomponents (i.e., replaceable) should be avoided to minimize the impact associated with replacements. With a view to ensuring net environmental benefits from reuse, it is crucial to attain the desirable reusability level through developing proper design and deconstruction strategies for individual modular components.Published here