Air-source energy, also known as air-source, refers to the low-grade thermal energy contained in the air. The law of conservation of energy tells us that energy cannot be created or destroyed. However, according to the laws of thermodynamics, heat cannot transfer from a low-temperature object to a high-temperature object without causing other changes. Although air-source energy is limitless, to transfer the absorbed energy from the air to a high-temperature environment, electrical or thermal energy must be consumed. This technology is called an air-source heat pump.