Impact of prefabrication technology on the cradle-to-site CO2 emissions of residential buildings

Abstract

In recent years, the industrialization of construction has been promoted to achieve sustainable development within the construction industry; accordingly, prefabrication technology has been utilized substantially. Due to enormous carbon emission reduction pressure, the carbon-reducing potential of prefabrication has attracted widespread interest. To deepen the current understanding of the carbon emission performance of prefabrication, this study investigates the differences in CO2 emissions between the prefabricated and conventional construction methods and the effect of the prefabrication rate on building carbon emissions. A quantitative model is established based on life-cycle assessment (LCA) to calculate the cradle-to-site CO2 emissions of the two construction methods. The LCA model is then parameterized to simulate the cradle-to-site CO2 emissions at varying prefabrication rates. The simulation is conducted based on three scenarios, i.e., some slabs and staircases are prefabricated, all transverse members are prefabricated, and all components are prefabricated. Two sample buildings in China, where housing industrialization has developed rapidly, are used for a preliminary examination. The results show that the conventional building produces 185.13 kgCO2/m2, whereas the prefabricated building produces 151.84 kgCO2/m2, which is approximately 18% lower than the former value. Additionally, the CO2 emissions do not necessarily decrease with an increase in the prefabrication rate. The building with some prefabricated slabs and staircases produces the least CO2 emissions, and the building with the highest prefabrication rate still produces less CO2 emissions than the conventional building. Moreover, as the prefabrication rate increases, the carbon emissions during the construction cycle present a shift towards manufacturing and transportation. Therefore, adopting prefabrication technology contributes to significant environmental benefits for reducing CO2 emissions; the optimal prefabrication rate can be chosen according to the demand. Carbon reduction in manufacturing and transportation should be a new focus.