A production line-based carbon emission assessment model for prefabricated components in China

The construction industry is characterized by high-energy consumption and intensive-carbon emissions. With the promotion of energy-saving technologies in buildings combined with concerns for global-warming, there has been a gradual shift in energy conservation requirements from the operation stage to the construction stage. This shift is primarily delivered through the use of improved materials and technologies implemented during the building construction stage. Building industrialization is an innovative construction approach that has experienced rapid up-take in China. The use of prefabricated components in building construction is now a key feature of the building industrialization process, and thus warrants greater attention in terms of its energy consumption and carbon emission. This paper utilizes a process-based method to assess carbon emissions during the prefabrication manufacturing process in offsite factories. A life cycle assessment is applied to a case study concerning a prefabricated concrete interior wall board. Carbon sources during the manufacturing process is identified and the carbon emissions are quantified using a factor method. The results show that carbon emissions from the interior prefabricated concrete wallboard of volume 0.609m³ is 427 kg, with the vast majority of the emissions originating from building materials, at 96.2%. The carbon emissions from electricity consumption constitutes 3.65%, and that from workers make up only 0.16%. The findings of this study offer a carbon emission benchmark for building industrialization, which in turn serve as a solid data foundation for carbon assessment of prefabricated buildings in China.