Direct Digital Control- A Tool for Energy Management of HVAC Systems

Direct digital control (DDC) applied to heating, ventilating, and air-conditioning (HVAC) systems corrects many of the deficiencies of conventional automatic temperature control systems. By applying new control sequences, DDC optimizes HVAC energy use. DDC can reduce HVAC operation and maintenance time and provide the environmental conditions needed to maximize production. DDC technology uses standalone, microprocessor based controllers. Controllers directly sense and process control variables (e.g. temperature, pressure) and provide a control signal to an actuator. Personal computers provide remote or local access to the digital controllers and give HVAC mechanics, energy managers, and facility engineers capabilities that conventional control systems do not offer. This paper discusses the most common deficiencies of conventionally controlled HVAC systems, advantages of DOC systems, and a case study retrofit from pneumatic control to digital control