The spherical shell model considering three heat-transfer modes is developed. Relationships among wall thickness, inside radius, package duration, ambient temperature, convection coefficients, emissivity of the insulated material surface and product size are developed and discussed. General conclusions are reached as to these variables and input parameters. Based on this model, the optimal insulating packaging solution is achieved by using ‘minimum packaging cost’ as an optimization target. This optimized design on the spherical shell model can be then transformed back to rectangular configurations by using the same rule used for transforming rectangular configurations to the spherical shell configuration. The comparison of results predicted from the present model with benchmark experimental data show satisfactory agreement in terms of packaging duration.