Embodied Carbon Footprint Analysis of Prefabricated Buildings Considering Assembly Schemes

The construction industry is one of the fields with the largest energy consumption and carbon footprint, and it is also a key and priority field for reducing carbon footprint. Prefabricated buildings have become an effective solution to industrial problems such as labor shortage, low construction efficiency and emission reduction. However, previous studies mostly focused on the energy saving and emission reduction during the operation phase, but paid less attention to the implied carbon footprint, and did not analyze the impact of the assembly scheme on the carbon footprint in combination with the national prefabricated building standards. In this study, the life cycle assessment method (LCA) was used to establish the evaluation framework of the embedded carbon footprint of prefabricated buildings, and a case was selected to verify the calculation. Furthermore, scenario analysis method was applied to explore the impact of assembly rate on carbon footprint under different assembly schemes under the evaluation standards of Prefabricated Building Evaluation Standards (GB/T51129-2017). The results show that the carbon footprint of the embodied stage of the prefabricated building is 463.03 kgCO2e/m2, and the largest proportion is in the production and transportation stage of building materials (95.91%), among which concrete, steel and brick produce more carbon footprints, and the factory production, component transportation and on-site construction and assembly stage related to the construction characteristics of the prefabricated building account for 1.45%. In addition, the carbon footprint increases with the increase of assembly rate, and the environmental burden of material suppliers is gradually transferred to prefabricated component suppliers and logistics providers. However, as the assembly rate continues to increase, the carbon footprint gradually increases slowly. According to the relationship between the assembly rate and the carbon footprint, it can assist the decision-making of the design scheme and the organization and scheduling, so as to reduce the carbon footprint in the embodied stage and improve the construction environment.