Numerical Analysis on Thermal Behavior of Composite Wall Combined Autoclaved Aerated Concrete With Thermal Insulting Material in Summer Day

Abstract Thermal insulation material (TIM) is commonly employed to enhance the thermal behavior of the lightweight walls. To further obtain the energy-saving effect of the walls, the composite wall (ATIM) combined autoclaved aerated concrete (AAC) block with TIM was present in this study. A testing rig with an ATIM wall was constructed and tested in summer design days, while the numerical modeling was developed and validated using the experimental data. Furthermore, reference walls of the brick and AAC with the same dimension as the ATIM wall were established to evaluate its thermal behavior. The thermal behavior and economic evaluation of the ATIM wall were then investigated by varying the thickness and position of the TIM using the numerical method. And the research results indicated that: (1) the average inner surface temperature of the ATIM wall is approximately 1.1 °C lower than that of the AAC wall, 1.3 °C lower than that of brick wall, the thickness of TIM is positively correlated with decreasing wall surface temperature, while TIM positions have minimal impact on reducing surface temperature; (2) heat gain reduction ratio for ATIM wall (δ = 20 mm) is approximately 52.7%, which is 8.1% higher than that of AAC wall, and variation in TIM position can decrease the heat gain, with inside or outside placement being more effective than positioning it in the middle part; (3) CO2 emission saving (CO2ES) and electricity cost saving (ECS) for room C (ATIM wall) is approximately 7.05 kg/100 m3/day and 5.23 RMB/100 m3/day, respectively, outperforming room A (brick wall) and room B (AAC wall) in terms of energy efficiency and economic benefits.