Understanding Energy Management, Building Automation, or Direct Digital Control
Energy Management Systems, Building Automation Systems, or Direct Digital Controls, one of the same, can be defined as a fully functional control system. It combines hardware and software with HVAC, lighting systems, emergency alert systems, and other mechanical-electrical equipment on a communication network with the ability to remotely control and monitor all systems. These systems are often seen as complex and highly technical requiring technicians and engineers with specific skills and education to understand, install, troubleshoot, and repair if necessary. As with any type of modern state of the art system, if one were to break the system down into individual components or sections, study these sections, and then put it all together one can grasp how these systems function individually and strategically. Even skilled technicians and engineers within the energy management business break these system down in order to solve problems and tune the systems.
The Basic DDC Control Loop
If you want to break down Direct Digital Control (DDC), Building Automation Systems (BAS), or Emergency management Systems (EMS) a good place to start is the basic control loop. It is the fundamental basis of all control systems. There are three basic functions which define the basic control loop. These three functions are:
- (Input Functions) A method of collecting and measuring data. Requires input from a sensor or device. This can be analog or digital. In this step we are Measuring temperature or C.F.M.’s (any variables) and collecting data. DDC building automation inputs basically measure a medium or monitor the HVAC systems such as smoke detectors and high/low limit switches. DDC inputs measure temperature, humidity, pressure, current, wattage, and air and water flow among other things.
- (Processing & Logic Functions) A method of processing the data collected. Requires a DDC or building automation controller to process information and which holds the logic or programming. In this step the DDC or building automation controller is processing the information from the input device(s) and based on the algorithm, possibly sending an output signal to a device to take appropriate action if necessary. The input device(s) does not need to be hard wired to the local equipment controller nor does an output response from the local equipment DDC building automation controller going to effect the DDC building automation controllers local equipment. Over a communication trunk the DDC or building automation controller can receive input signals from distant automation controllers and issue output commands to those same or other distant building automation or DDC automation controllers. It really depends on the program and set-up of the entire system in the algorithms of the building automation system as a whole.
- (Output Functions) A method(s) of causing a controlled output for a controlled device. The actual device being controlled is based on what the input is feeding to the DDC controls controller. In this step the controlled device is taking action to maintain the program based on program variables and logic. Output devices can be damper actuators, valve actuators, relays (electrical and or pneumatics (p-e or e-p), variable frequency or speed drives, compressors, blowers, and pumps.
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Energy Efficiency 
