Abstract: This invention provides a novel, inexpensive, universal energy control computing accessory module for altering at programmed times the operation of existing adjunct thermal/ventilation systems. In the module, interactive programming of control timing permits the accessory to be easily adapted for different types of adjunct installations to produce timed control signals particularly adapted for control of the particular installed system. One typical mode of operation is to turn on or off cyclically the thermal/ventilation system to run at a prescribed timing duty cycle. The invention may be used for diverse utility modes of operation, such as providing periodic ventilation controls for an unattended beach vacation home or for providing semi-automatic control of installed heating or air conditioning systems during occupancy of hotel rooms, dwellings, or stations within commercial buildings, as sensed by auxiliary detection means.