Direct Digital Control (DDC) is becoming the standard for maintaining control of a facility’s critical systems. It is a popular choice for residential and commercial buildings, used primarily in commercial heating, ventilation and air conditioning (HVAC) control and energy management system applications. Operators are finding that DDC systems can simplify processes and allow for system automation and energy efficiency in the workplace.


What Is Direct Digital Control?

DDC systems control a building’s conditions through a central computer that monitors performance. DDC systems monitor functions, such as temperature and lighting via sensors and output signals, such as to control valves, open doors, and sound alarms.

A building automation system (BAS) uses a DDC system to automate the control of various building systems. DDC and BAS work together to provide programmable and precise control of a building’s functions, increasing a building’s energy efficiency and warning when a system is at risk. The DDC system that controls a commercial HVAC system may also control other building systems, such as mechanical and electrical systems, to automate the entire building.

19Implementing DDC can provide you technological benefits including central monitoring and control, monitoring trends reports, improved energy efficiency, smart security, easier maintenance, simple climate and lighting control, simple retro-commissioning and increased safety.

Benefits of Direct Digital Control

Central Monitoring: DDC allows for remote monitoring of equipment, such as an HVAC system, from a central location. Remote monitoring of DDC controls means that facility personnel can monitor their equipment 24/7. In addition, personnel can easily check the status of each component and the entire system in order to identify problems and change system operations before components become critical or result in system failure. These operations could include opening/closing valves, starting/stopping fans or changing setpoints.

Monitoring Trends: A DDC system can monitor trends that indicate potential system problems and can make operational adjustments as necessary. Usually, trended data include temperature, pressure, humidity and times of operations, as well as others. This data is critical to identify appropriate modifications of a building’s DDC systems for optimal performance and efficiency.

Boosting Energy Efficiency: Energy-efficient schedules, such as optimal start/stop modes and temperature reset schedules, can be programmed to control equipment to save energy and money.  Further, monitoring energy consumption permits changes of various set points to ensure efficient utilization of energy.  For instance, sensors can monitor multiple conditions and can change operations to reduce energy consumption. By integrating the right sensors with specific software, building and property managers can quickly view the level of efficiency of the building and its components.

Smart Security: A building’s automation can include a security system customized with DDC, based on business needs. Motion sensors can be connected to the DDC system to control lights when someone approaches an area of the building, thereby providing increased safety for occupants. Also, using key fob entry eliminates the need to find keys and manually unlock the door, increasing the speed of entry into the building.

Easier Maintenance: DDC systems communicate alarm conditions that help operators evaluate the situation and thus take necessary action. For example, sensors located on HVAC systems can send alerts when a component is not functioning properly. Analysis of sensor data can ensure action prior to a critical fault can add to a facility’s ability to reduce downtime risk.

Simple Climate and Lighting Automation: DDC controls make it easy to set and control climate and lighting systems from any computer that contains the DDC control software. For instance, a well-designed DDC system can reduce workloads by automating lighting according to a set schedule in order to save money. With central, automated control of the climate, quick response to environmental changes maintain more stable temperatures and improved comfort in real time.

Simple Retro-commissioning: DDC allows for retro-commissioning, by simply changing the software so it can provide more detailed information. To perform retro-commissioning by changing hardware is more time consuming and costly. Another benefit is that, after software changes have been made, observation of the system can produce essential data on its functionality within a short time.

Increased Safety: Integrating life safety and access control systems and DDC systems into an internet platform can give owners and operators real time information and can control the environment, thus increasing safety. For example, integrated smoke controls systems and indoor gun-fire detection systems can take advantage of sensors placed on existing building networks.


Overall, DDC systems and automation offer control over a building’s functions and can help increase a building’s comfort levels while reducing its energy consumption.


Trevillian has a master’s degree in computer science. Her experience includes analytical research.