This incentive is available for an existing air compressor with the current air inlet coming from the ambient conditioned (heated) space and proposing to permanently hard duct the air inlet directly from the outside. Outside air is, on average, cooler than the conditioned inside air, and colder air is denser and requires less energy to compress. Consult the compressor manufacturer to ensure the air compressor can address the increased static pressure drop on the ducted air intake and the potentially cold air temperatures without adverse effects.