Hybrid Life Cycle Assessment (LCA) of prefabrication: A comparison of conventional and mixed reality-based solutions

Conventional prefabrication in construction is causing distinct challenges, including environmental pollution and high energy usage. However, integrating emerging technologies such as Mixed Reality (MR) in prefabrication is expected to mitigate the environmental impacts and improve overall sustainability. This study evaluates and analyses the environmental benefits and burdens associated with implementing MR technologies in prefabrication compared to conventional prefabrication. The production stages in prefabrication, including reinforcement, side formworks, concreting, and human labor, have been identified as primary unit processes, and their respective contributions to the overall environmental impact have been assessed. A comprehensive assessment using a hybrid Input-Output Life Cycle Assessment (IO-LCA) model, while incorporating human labor hours is necessary for a thorough environmental assessment. The cradle-to-gate LCA results of a declared unit of 1 m³ volume of conventional prefabrication are compared with MR-enabled prefabrication. The results show that using MR technology in prefabrication significantly decreases the environmental burdens of the prefabrication in impact categories of Global warming (8%), Terrestrial acidification (8%), Marine eutrophication (10%), and Stratospheric ozone depletion (17%). Furthermore, with the higher levels of MR implementation, there is a significant reduction (around 60%) in the environmental impact associated with prefabrication. Accordingly, the contribution of MR technology in designing, planning, monitoring, assembling, and collaborating in prefabrication leads to effective resource management, minimization of waste, and enhancement of overall efficiency. The reinforcement process has notably elevated environmental impact in prefabrication while recognizing the improvement opportunities through MR implementation. MR-enabled quality inspection is of great importance in significantly reducing environmental burdens.