Investigating the Sustainability of Modern Construction Practices Focusing on Prefabricated Construction

Prefabricated construction (PFC) is a popular modern method of construction (MMC) that has revolutionised the global construction industry. PFC is transforming the lacklustre performance of traditional construction processes by manifesting modernisation and technology and providing diverse benefits. However, the effective adoption of prefabrication in developing countries is considerably restricted compared to developed and industrialised economies. Research attempts in South Asian countries such as Sri Lanka are seldom considered due to insufficient R&D initiatives. Thus, it is imperative to investigate the contemporary status and the sustainability performance of these MMCs to promote their adoption. Despite many research claims over its sustainability benefits, understanding the sustainability performance of PFC through actual cases would provide real-time evidence to further promote prefabrication. Hence, the current research maintains a twofold perspective on the sustainability of PFC as sustainability evaluation and enhancement. Life cycle sustainability assessment (LCSA) is one of the comprehensive tools to evaluate holistic sustainability by integrating the three sustainability dimensions (environmental, economic, and social) from a life cycle perspective. A comprehensive literature survey conducted identified that the current knowledge body requires integrated methodological guidance to conduct PFC-related life cycle assessments (LCAs), life cycle economic assessments (LCEAs), social-life cycle assessments (S-LCAs) and LCSAs. Furthermore, little effort is directed towards properly studying relationships between LCSA indicators and sustainable development goals (SDGs) related to PFC. From the perspective of sustainability enhancement, rigorous efforts are needed to identify strategies to elevate the sustainability performance of PFC projects during their whole life cycle. Therefore, the current research aims to develop a lifecycle-based decision support framework for sustainability evaluation and enhancement of PFC. The following objectives will realise the aim: (1) Investigate the contemporary status of PFC in Sri Lanka and Australia, (2) Develop integrated methodological and assessment frameworks to evaluate the sustainability of PFC, (3) Develop a decision-support framework to enhance the sustainability of PFC, (4) Validate the developed frameworks for evaluating and enhancing PFC considering Sri Lanka and Australia. The current study followed a mixed-methods approach to accomplish the proposed research aim and objectives. A continuous literature survey, pilot studies, questionnaire surveys, expert-based validations, field visits and field and case study data gathering were done to reach study objectives. Further, data analysis approaches such as statistical methods, case study-based content analysis, qualitative content analysis, and life cycle-based assessment methods (LCA, LCC, S-LCA and LCSA) were incorporated to achieve the documented targets. The top three most significant barriers to adopting PFC in Sri Lanka include challenges in prefabricated component transportation, high capital investment cost and lack of awareness of the benefits of prefabricated construction among owners/developers. Furthermore, reduced overall project time (Fast delivery), efficient consumption of materials, and overall project cost savings ranked top as the most influential sustainability drivers for PFC adoption in Sri Lanka. Measurable indicator systems connecting with SDGs related to prefabricated construction aspects are crucial outcomes from the current research to support global sustainable development. The case study-based qualitative analysis found 66 sustainability performance indicators relevant to 157 completed PFC cases in Australia, where ‘High quality’ and ‘Reduced overall project time (Fast delivery)’ were heavily represented. The LCA study compared an office building in Sri Lanka and showed that the building with prefabricated components provides environmental impact savings. On top of that, the results highlighted that the design for the disassembly version of a modular building performed better in terms of all environmental impacts than the linear version. LCSA study outcomes showed that the social sustainability aspects of modular construction in Sri Lanka should focus more on elevating holistic sustainability performance compared to the Australian context. Moreover, the most critical strategy cluster for enhancing PFC sustainability in Australia is revealed as ‘Project level early design and strategic decisions’. Further, the study indicates that novel and new technology integration, effective supply chain, and operational management in PFC project life cycles are crucial to enhancing TBL sustainability. The developed knowledge-based decision support tool proposes an action plan to improve the readiness of these strategies for PFC sustainability enhancement depending on the user's assessment of individual decision-making factors. The academic contribution of the research is to create a robust basis for future research on the sustainability evaluation of PFC and other MMCs. The practical value of the study is to provide decision-making guidance to PFC stakeholders on enhancing sustainability performance and the contemporary status of PFC in developing (Sri Lanka) and developed (Australia) economies. Further, the current research intended to transfer knowledge and best practices from a developed country context, where PFC is advanced, to a developing country context, where PFC adoption is still not matured.<p></p>