Environmental comparative case studies on modular integrated construction and cast-in-situ construction methods

Abstract

This study contributes to the worldwide efforts of adopting innovative low carbon construction methods to reduce net zero embodied carbon of buildings and to minimize local environmental impacts during the construction period. It uses agent-based models (ABM) to simulate multi-threaded and multi-objective construction activities through collecting detailed project data of two case studies (one using the modular integrated construction (MiC) method and the other one using the cast-in-situ method) in Hong Kong. Considering that the construction process is dynamic and site issues are complex in nature, three major environmental impacts of carbon emissions, air pollution and noise are modelled at fine spatial and temporal resolutions. The findings show that the MiC project has significant environmental advantages over the cast-in-situ project in terms of reducing CO2 emissions, harmful emissions (including sulphur dioxide, nitrogen oxides, and organic volatile compounds), PM2.5 and PM10 emissions, and noise pollution levels, consequently reducing health risk associated with people in surrounding communities near construction sites. In terms of per square meter of construction floor area (per m2 CFA), the MiC project produced 17.60% less CO2, 42.54% less harmful gases, 32.15% less PM2.5 and 27.41% less PM10. The duration of noise exceeding 70 dB (minutes) in the neighbourhood of the MiC project was 81.25% shorter than the cast-in-situ project. The total health damage (in DALYs per m2 CFA) of the former was 63.18% lower than the latter. The research concludes that the adoption of low carbon construction methods like MiC can help to foster sustainable buildings and healthy communities in an urban context.