An active thermal insulation system is disclosed. The system utilizes a cool air source in conjunction with a phase change material and/or conventional insulation. In a controlled manner, the cool air source facilitates the transition of the phase change material from a substantially liquid state to a substantially solid state allowing the solid phase change material to absorb heat. Cool air may be directed to the phase change material via a duct, plenum or other suitable passageway capable of introducing the cool air to the phase change material. A system outlet allows heat created during the phase change material's transition from a liquid state to a solid state to be exhausted to the atmosphere or elsewhere. The system is ideal for desert and other warm weather climates.