Energy conservative control of heating, ventilating, and air conditioning (HVAC) systems

Apparatus for controlling an HVAC which provides hot and cold discharge air to a plurality of temperature controlled spaces through associated hot and cold decks connected to an air handler source, each space selecting a portion of the hot and cold air by position modulation of space dampers from a full hot air to a full cold air position in dependence on a selectable reference temperature associated with the space, the air handler including a heating source and cooling source which provide the hot and cold discharge air by conditioning the mixed air discharge from a mixed air source provided as a mixture of outside air and return air from the spaces in a ratio determined by the position of mixed air dampers included therein, the apparatus comprising:

• plurality of source temperature sensor means, disposed in the HVAC air handler source, for providing sensed signal information including an actual hot air discharge temperature signal and an actual cold air discharge temperature signal;
• plurality of space temperature sensor means, one each disposed in each of the temperature controlled spaces, for providing an actual space temperature signal;
• plurality of source control means, including a heating source control means and a cooling source control means, each operatively connected to the associated source and each responsive to actuating gate signals, actual discharge temperature signals and deck reference temperature signals presented thereto, said plurality of source control means each providing a turn on of the source associated therewith in response to the presence of said gate signal, and each providing regulation of the discharge air temperature from the source associated therewith in dependence on the difference temperature between said actual discharge temperature signals and said deck reference temperature signals;
• and
• electronic processing means, connected to said plurality of source control means and responsive to said actual space temperature signals, said processing means comparing each of said actual space temperature signals to the lower limit and upper limit of a temperature drift band defined, respectively, by a heat set point temperature signal and a cool set point temperature signal stored in a memory portion of said processing means, said processing means providing to said cooling source control means an actuating gate signal and a cold deck reference temperature signal in response to an actual space temperature above said cool set point temperature and providing to said heating source control means an actuating gate signal and a hot deck reference temperature signal in response to an actual space temperature below said heat set point temperature, said cold deck reference temperature signal and said hot deck reference temperature signal each having a magnitude in dependence on the product of a proportional plus integral gain signal stored in said memory multiplied by an associated one of a space hot temperature error signal and a space cold temperature error signal respectively, said processing means providing said space hot temperature error signal at a magnitude equal to the temperature difference between said cool set point temperature signal and the highest value of said actual space temperature signals above said cool set point, said processing means providing said space cold temperature error signal at a magnitude equal to the temperature difference between said heat set point temperature signal and the lowest value of said actual space temperature signals below said heat set point temperature.