Evaluation of Thermal Performance of Low-Cost Insulation Materials for Cold Storage in South West Nigeria

Cold chain infrastructure for agricultural produce and pharmaceutical products in South West Nigeria is constrained by the high cost of conventional insulation materials including polyurethane foam and extruded polystyrene. Identifying low-cost locally available insulation materials with adequate thermal performance would expand access to cold storage for smallholder farmers and rural health centres. This study evaluates the thermal conductivity, density, moisture resistance, and mechanical stability of five candidate low-cost insulation materials including coconut fibre mat, rice husk composite board, sawdust-cement board, plantain fibre batt, and recycled newspaper pulp board. Thermal conductivity is measured by the guarded hot plate method at mean temperatures of 25 and 35 degrees Celsius. Moisture uptake is assessed after 48-hour water immersion. Compressive strength is determined at 10 percent deformation. Results indicate thermal conductivities ranging from 0.038 W per metre-Kelvin for coconut fibre mat to 0.087 W per metre-Kelvin for sawdust-cement board. Coconut fibre mat achieves thermal performance closest to commercial mineral wool (0.036 W per metre-Kelvin) at an estimated raw material cost 80 percent lower. Rice husk composite board offers the best combination of thermal performance, mechanical strength, and moisture resistance. Keywords: thermal insulation, cold storage, low-cost materials, coconut fibre, South West Nigeria