3023 -- Demand-Controlled Economizers PDF

An experimental control system was built at a university that used a microprocessor to measure the heating and cooling demands on a dual-duct HVAC system and provide optimal control of the outside air dampers. Measurements taken during a three-month test showed the coil-operating costs were reduced more than 20% during February and March and more than 30% during April. Computer simulations that extended over a full year predicted annual savings of at least 22% compared to a system that provided only minimum ventilation air. Heated thermistor flow sensors were built especially for this experiment, and their performance, as well as that of the entire HVAC system, is discussed.

Units: I-P