Thermal and structural analysis of n-heptadecane-applied form-stable heat storage aggregate integrated rice husk ash-red clay boards for improving building energy efficiency

•Heat storage aggregate contained 50% n-heptadecane by mass.•HS-RH board's theoretical latent heat is 4.08–11.66 J/g.•HS- RH board exhibited increased ductile fracture behavior.•Higher heat storage aggregate content delayed heat transfer.•FS-HSA in HS-RH board reduces energy consumption with latent heat effect. Applying phase change materials (PCMs) to the building envelope is an effective way of improving indoor thermal comfort and reducing energy consumption. The two main drawbacks of PCMs are low thermal conductivity and leakage during phase change, limiting their practical application in thermal energy storage. In this study, a form-stable heat storage aggregate (FS-HSA) was manufactured by impregnating rice husk ash with n-heptadecane, which was mixed with hwangtoh to form a heat storage rice husk ash-hwangtoh board (HS-RH board). Results showed uniform distribution of FS-HSA within the board, with 50 % n-heptadecane content. Theoretical heat storage capacities of HS-RH boards containing 10 %, 20 %, and 30 % FS-HSA were 4.19, 8.08, and 11.66 J/g when heated, and 4.08, 7.86, and 11.35 J/g when cooled. The board with higher FS-HSA content exhibited more ductile fracture behavior. The dynamic heat transfer analysis confirmed that PCM application affects the heat transfer delay due to the specific heat and latent heat storage performance. In the building energy simulation analysis, the building model with more FS-HSA in the HS-RH board had lower energy consumption due to the latent heat effect.