Carbon emission calculation of prefabricated concrete composite slabs during the production and construction stages

Prefabricated buildings provide favorable technical support to achieve the "carbon peak and carbon neutral" target in the building field. The accurate and reliable quantification of building carbon emissions is an important basis to achieve the dual carbon target. However, research on the carbon emissions of prefabricated buildings is limited, and few studies have been conducted on the calculation of carbon emissions from prefabricated components. Based on the process inventory analysis method, the carbon emission calculation model for prefabricated components in the production and construction stages was established. The prefabricated concrete composite slabs and cast-in-place floor slabs of two typical residential buildings were selected for the case study, and a comparative study was conducted on their carbon emissions during the production and construction stages. The results indicated that the carbon emissions per unit area (net floor area) of prefabricated concrete composite slabs (43.31 kgCO2e/m2 and 43.01 kgCO2e/m2, respectively) were lower than those of cast-in-place floor slabs (46.32 kgCO2e/m2 and 46.09 kgCO2e/m2, respectively) in the production and construction stages. The carbon emissions in the production and construction stages of prefabricated concrete composite slabs accounted for about 97.45 % and 2.55 %, while those of cast-in-place slabs accounted for about 91.21 % and 8.79 %, respectively. The carbon emissions at the building material production stage mainly originated from rebar and cement. When the change rate of building materials consumption and materials carbon emission factors was the same, the change rate of carbon emissions per unit area was ranked as rebar > cement. Furthermore, the cases showed that the prefabrication rate of case B was higher than that of case A, but the carbon emissions per unit area of case B were lower than those of case A. This study provides a scientific calculation method for the carbon emissions of prefabricated components, as well as enriches the data for studying building carbon emissions.