Investigating waste reduction potential in the upstream processes of offshore prefabrication construction

The construction industry around the globe has been increasingly advocated to utilize prefabrication to minimize waste, thereby alleviating associated negative impacts on environment and the society. Previous studies have reported on waste reduction potential from adopting prefabrication in various economies including Hong Kong. A significant shortcoming of these studies; however, is the neglect of the upstream processes of prefabrication including the manufacturing and transportation of components, which causes construction waste as well. To date it is still unclear how this portion of construction waste is generated and quantified. The issues are even more complicated in Hong Kong where components are manufactured in the offshore Pearl River Delta Region (PRDR) of mainland China and transported across the border to construction sites in Hong Kong. Against the theoretical backdrop of whole life cycle thinking, the aim of this study is to empirically investigate the manufacture and cross-border transportation processes, thereby to assess the waste reduction potentials of using prefabrication in construction. It does so by conducting three in-depth case studies with selected PRDR prefabrication factories. A hybrid of research methods are employed in the study. It is found that the waste generation rate in the upstream processes of offshore prefabrication is around 2% or lower by weight. This proves the orthodox that prefabrication in a factory environment is more conducive to waste reduction than the traditional cast in-situ construction manner. However, transporting the components adds cost and simultaneously increases the risk of waste generation. This study provides insights into understanding construction waste reduction through offshore prefabrication from a holistic view.