| Author: | Hsu, Kam Ming |
| Title: | Exploring environmental impacts from cradle-to-gate and end-of-life phases for adopting Modular integrated Construction (MiC) in Hong Kong by case study using Life Cycle Assessment (LCA) approach |
| Advisors: | Chi, Hung-lin (BRE) |
| Degree: | DIREC |
| Year: | 2024 |
| Department: | Department of Building and Real Estate |
| Pages: | xix, 336 pages : color illustrations |
| Language: | English |
| Abstract: | With the strong acceleration of technological innovation that was unveiled in the Construction Industry of Hong Kong, Modular integrated Construction (MiC) aims to convert conventional construction methods to a Lego-esque manner, it has been rapidly promoted in Hong Kong due to its advantages with sustainability. It offers numerous advantages over the conventional method, but their overall environmental impacts remain uncertain. The study of end-of-life impact associated with modular buildings remains largely unexplored in Hong Kong. In addition, research using the Life Cycle Assessment (LCA) framework to systematically evaluate the impacts of environmental sustainability of adopting MiC throughout the entire building lifecycle is notably scarce. The primary study emphasis is to utilize the LCA approach "ReCiPe2016" at the midpoint level with the global scale to review environmental impacts from cradle-togate and end-of-life phases of the building life cycle for growing MiC adoption compared to the conventional construction method through the case study in Hong Kong. The research was organised and executed in three phases. The initial phase consisted of conducting an extensive literature review to explore the benefits and drawbacks of MiC in Hong Kong and their interrelation with key criteria for achieving sustainability across the building life cycle. The second phase of this study consist of an inventory analysis that tracks the input and output processes within defined system boundaries, covering material extraction, production, construction, and end-of-life phases. The final phase involved conducting a LCIA to assess the environmental performance of MiC versus conventional construction methods. This assessment was performed using SimaPro LCA software, allowing for a detailed comparison and interpretation of the results. The research findings offered valuable insights into the environmental sustainability of MiC rapidly emerging in Hong Kong and informed stakeholders about various trade-offs from the design to implementation and the end-of-life implications of using MiC. Furthermore, the findings suggested realistic alternatives to encourage the adoption of MiC in the industry while also contributing to enhancing sustainable building practices and policies in Hong Kong, particularly to widely apply MiC as an alternative construction method with recommendations and optimised adoption module and design approach. The assessment results from cradle-to-gate and end-of-life phases in the building life cycle revealed that neither conventional construction methods nor MiC are the absolute options for achieving environmental sustainability. The comparison of characterized results for each impact metric across all cradle-to-gate and end-of-life periods revealed that the conventional construction method (Case 7) exhibited a more favourable environmental profile in 8 out of 18 impact categories. It is crucial to recognise that in the global warming impact assessment, both concrete MiC (Case 2) and conventional private residential (Case 7) exhibit a similar top environmental performance compared to other study cases. Notably, concrete MiC (Case 2) has superior overall environmental performance after normalization of the impact categories. Although the concrete MiC (Case 2) is built using modular construction with the best overall performance among all the MiC and conventional cases, it does not show significant environmental advantages over conventional construction methods in the studied scenarios. Furthermore, the negative impacts dominated the material production phase compared to the construction and end-of-life phases in all study cases, owing to the significant contribution of the impacts with the use of high embodied-carbon materials. The positive effects of steel MiC realised in the construction and end-of-life phases are incapable of compensating for detrimental impacts incurred during the material production phase. With consideration of overall environmental impacts, the contribution in the material production phase was notably high compared to construction and end-of-life phases, primarily caused by energy embedded in materials and the energy consumed from material extracting and processing. The end-of-life impacts of concrete modular constructions, including those with more complex features such as double walls and floors, are minimal. Furthermore, the study highlighted that the larger floor area of the concrete MiC with two bedrooms flat unit performed better environmentally than those with one bedroom only, and steel MiC with open kitchen flat unit also showed better result than other steel MiC configurations. The findings further confirmed that the significance of material usage in the material production phase must be addressed when adopting MiC design in Hong Kong. Despite the various advantages in the construction phase, the MiC approach is not the most optimised option for sustainability within the environmental dimension. Particularly, some of the current module designs under the pre-accepted list by the Hong Kong Building Department exhibit considerable environmental drawbacks without significant benefits in the material production phase over conventional methods. Consequently, these results provide an opportunity for the Government and relevant stakeholders to reassess and refine current MiC design configurations, adoption strategies and policies, aiming to enhance and balance sustainability within the environmental dimension across the entire building life cycle to facilitate expanding MiC residential housing projects in Hong Kong. |
| Rights: | All rights reserved |
| Access: | restricted access |
Files in This Item:
| File | Description | Size | Format | |
|---|---|---|---|---|
| 7624.pdf | For All Users (off-campus access for PolyU Staff & Students only) | 31.98 MB | Adobe PDF | View/Open |
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