Dynamic thermal behavior of fly ash hollow microspheres-mineral fiber low-carbon composite insulation wall: experimental and simulation study

As the demand for renewable resources continues to rise, traditional energy structures face significant challenges, particularly as the use of coal fails to effectively reduce carbon dioxide emissions. Approximately one-third of global coal consumption is used by power plants in China, creating new opportunities for utilizing fly ash waste in combination with low-carbon building materials. This study develops a novel low-carbon insulation board using coal-derived fly ash hollow microspheres (FA) and mineral fibers (MF) through vacuum drying technology. Systematic characterization via thermal conductivity measurements (0.018 W/m·K post-treatment) and SEM reveals hierarchical porous structures enabling exceptional thermal resistance. A combination of experimental and simulation methods was employed, including thermal box testing and the development of a simplified thermal network model for composite walls. The model's reliability was validated through experimental measurements, enabling a systematic analysis of wall thermal performance, thermal response, and dynamic characteristics under different boundary conditions. The FA-MF composite insulation board demonstrates excellent thermal insulation properties. Compared to traditional materials such as EPS boards, it significantly reduces the indoor peak temperature and delays the onset of the peak temperature by 2.17–2.84 h, greatly improving indoor thermal stability and comfort. The daily energy consumption is reduced by 42.9 %. Additionally, the attenuation coefficient in summer exceeds that in winter, indicating a stronger resistance to temperature fluctuations. These findings establish FA-MF composites as high-performance thermal regulators, offering dual benefits of industrial waste utilization and building energy conservation.