Abstract: An improved energy saving control apparatus particularly designed for providing energy saving control of individual room heating and cooling units in direct response to the active occupancy status of the room. Switching means selectively interrupt energization of the load element of a room heating/cooling unit in response to an interrupt control signal. An electronic energy saving control circuit responds to changes in the ambient air room temperature and overrides the heating/cooling unit thermostat to selectively generate the interrupt control signal for maintaining the ambient air room temperature within a broad predetermined and pre-settable energy saving temperature range whenever the room is not actively occupied. Occupancy status detector means, including a uniquely detectable and detachable member typically carried by the room occupant and cooperative detector means within the room provides a real time indication of the active occupancy status of the room.