Determining heat load of the system is the first step in selecting the proper TEM for the application. The total heat load may consist of active heat load, passive heat load, or a combination of the two. An active load is the heat dissipated by the device being cooled. It generally equals the input power to the device. Passive heat loads are parasitic in nature and may consist of radiation, convection, or conduction. Minimizing the heat load allows the module to achieve colder temperatures or reduces the power required to reach a defined cooling level. Accurately calculating the heat load will ensure that the proper TEM is selected for the needs of a design.