This experiment was conducted to compare the thermal insulation properties of materials. The tests were done to compare the cooling rate of boiling water using air, sand and Styrofoam as insulators. Sand is able to keep water warm for the longest period time, when compared to air and Styrofoam. Thermal insulation. Thermal insulators are materials that are used to reduce, minimize or prevent heat transfer from occurring. Heat transfer happens through conduction, radiation or convection.