Thermal performance evaluation of Guinea Corn Husk Ash-modified sandcrete blocks using computational fluid dynamics simulation

In hot tropical regions such as Nigeria, the growing demand for cooling energy is driven by the use of sandcrete blocks with poor insulation in affordable housing. This study evaluates the potential of Guinea Corn Husk Ash (GCHA), an agricultural by-product with pozzolanic properties, as a partial cement replacement to improve thermal performance. Four block compositions (0–15% GCHA replacement of cement weight) were analysed using steady-state heat transfer simulations in ANSYS Mechanical. Standard indoor–outdoor boundary conditions were applied, mesh independence tests confirmed numerical accuracy, and the model was validated against benchmark studies. Thermal conductivity, heat flux, U-values, and R-values were extracted from the simulations. Results showed that the incorporation of GCHA generally enhanced the thermal performance of the blocks, with the most significant improvements in thermal resistance observed at higher replacement levels. At 15% replacement, maximum heat flux decreased by over 35% relative to the control, U-values reduced from 1.67 to 1.09 W/m²·K, and R-values increased to 0.92 m²·K/W. These gains were attributed to increased porosity and reduced density. Although the Nigerian Building Energy Efficiency Code (BEEC) has yet to set wall U-value requirements, the benchmarks reported here provide practical reference levels that could guide future code development and support low-cost, energy-efficient housing.