This study aims to investigate the hygrothermal performance of a multilayer concrete wall assembly incorporating foamcrete as an insulating material within whole building dynamics. The 226-mm-thick wall includes plaster layers on both interior and exterior surfaces, with foamcrete densities of 800, 600, and 400 kg/m³ and an external weather-resistant barrier for enhanced weather resistance and moisture management. Hygrothermal simulations were conducted for Harbin and Guiyang, representing hot, humid, and cold climates in China, respectively. Results indicate substantial reductions in heat loss with the addition of foamcrete layers, ranging from 17 to 42 % compared with a normal concrete wall, depending on foamcrete density and thickness. Improvements in interior surface temperature and relative humidity were observed; the lowest internal temperature increased from 0.43°C to 14.07°C, and relative humidity decreased from 100 to 70 %. Additionally, the impact of varying foamcrete densities on the heating and cooling loads of entire buildings was examined, showing significant reductions in both loads. Notably, using 400-kg/m³ foamcrete reduced the heating load by 53.342 % and the cooling load by 26.8 % compared with the reference model. These findings underscore foamcrete’s potential as a viable insulation option for concrete walls, offering significant energy savings and cost reductions in building operations.