Effects of various connectors on the whole-life-cycle energy consumption of sandwich wall panels in five thermal zones of China

Connectors are not only an important mechanical component of sandwich wall panels (SWPs), but they also contribute to SWP energy loss because they penetrate thermal insulation layers. Reducing the energy consumption (EC) generated by connectors is critical for improving the energy-saving efficiency of SWPs throughout their life cycle. The mechanical and thermal parameters of connectors, structural layers, and insulation layers all have a coupling effect on the EC of connectors in the SWPs studied in this study. First, a connector diameter calculation model and a three-dimensional finite element (3-DFE) model were developed to investigate the mechanism of various connectors' effects on the thermal performance (TP) of SWPs with different structural and insulation layers. Due to the high shear strength of steel, the diameter of the steel connector was found to be 59% smaller than that of the FRP connector, and the thermal bridge effect of the steel connector is reduced by 78% at most when the coupling effect is considered. Then, based on TP, a life cycle cost assessment (LCCA) model was developed. Using five thermal zones in China as research subjects, it was discovered that the effects of connectors on the whole-life-cycle EC of SWPs depend on the value of degree days (DD). Steel connectors can reduce the total energy consumption cost of SWPs by up to 13.7% in Guangzhou when compared to GFRP connectors. The connector manufacturing EC dominated the whole-life-cycle EC in an area with a low DD value. Reduced thermal conductivities of structural layers could significantly improve the effects of connectors on the whole-life-cycle EC of SWPs in an area with a high DD value. These findings are critical for the development of effective SWPs.