US Patent 9121620 Energy efficient HVAC system

An energy efficient HVAC system. The system provides a bypass air supply duct, an air handler having a bypass air supply circuit, and an air supply unit that utilize return air as a source of heat that would otherwise need to be provided by a heating coil if the air, cooled sufficiently to service interior zones of a building, is too cold for servicing perimeter zones of the building, as is typically the case when the outside air temperature is low.