What BAS/DDC Does for Facilities

HVAC Controls, building automation (BAS), direct digital control (DDC Controls) are at the heart of many energy management systems for energy savings. Many of you may be wondering what Direct Digital Control (DDC Controls) is and what and where it is used. DDC Control Systems are mainly used in commercial HVAC control and energy management system applications in building automation. DDC & building automation itself is an energy management system which saves management companies and building owners hundreds of thousands if not millions of dollars every year by efficiently controlling air conditioning and heating comfort systems. DDC is where mechanical and electrical systems and equipment are joined with microprocessors that communicate with each other and possibly to a computer. This computer and controllers in the building automation system can be networked to the internet or serve as a stand alone system for the local peer to peer controller network only. Additionally, the controllers themselves do not need a computer to operate efficiently as many of these controllers are designed to operate as stand-alone controllers and control the specific equipment they are assigned to control. With a few exceptions, each DDC or building automation controller holds their own programs and has the ability to communicate to other DDC building automation controllers. It is important for the DDC or building automation controllers to communicate to each other. If the network fails for whatever reason then the system may still function (because the DDC controllers in building automation systems are stand-alone) but it will not function as efficiently as designed. Building Automation & DDC Control Systems grows more and more complex as time passes but it will save in energy and maintenance costs if installed and programmed properly. Energy Management Systems, DDC Controls Systems and Building Automation Systems (can be one in the same) are definitely the way of the future and are replacing older less efficient systems everyday.

A set-up in a multi-story automated building would have many DDC building automation controllers serving different types of air conditioning and heating equipment (ddc is not limited to just hvac applications). Every building is different and it is important for the engineer to select the proper control system and programs to control the various types of systems in a particular automated building. For building automation systems to be effective, it is important that the system is installed and tuned properly. Some advantages of a good HVAC DDC building automation system are:

• DDC/building automation system (BAS) should allow the owner to set up schedules of operation for the equipment and lighting systems so that energy savings can be realized when the building or spaces in the building are unoccupied.
• DDC/building automation system (BAS) should allow the equipment optimal start with adaptive learning. Optimal start is allowing the equipment to be brought on in an ordered and sequential manner automatically on a schedule before the building is reoccupied so that space set points can be realized before occupation. Adaptive learning allows the system to compare space temperature, outside air conditions, and equipment capabilities so that the equipment can be turned on at an appropriate time to ensure space set points are achieved before occupation.
• DDC/building automation system (BAS) should have trim and respond capabilities. Based on zone demand the set point for various heating and cooling sources will change according to demand from the zones. In a VAV system all the VAV boxes are served from a central air handling unit. If all the zones are at set point then the supply air temperature set point of the air handler is automatically changed to prevent mechanical cooling from occurring when it is unnecessary. When the zones grow warmer the supply air temperature set point is automatically lowered to allow mechanical cooling to satisfy demand. Older systems have a single supply air temperature set point of 55° Fahrenheit which requires the compressors to cycle even when it is not necessary.
• DDC/building automation system (BAS) should have the ability to monitor energy usage including the ability to meter electric, gas, water, steam, hot water, chilled water, and fuel oil services.
• DDC/building automation system (BAS) in conjunction with the appropriate mechanical system set-up should offer economizing based on enthalpy calculations and/or CO2 set point control.
• DDC/building automation system (BAS) should have such DDC control algorithms as reset schedules for heating plants, static pressure control, and other systems where energy savings can be realized through these predictive programs.
• DDC/building automation system (BAS) should offer load shedding when power companies are at peak demand and need business and industry to cut back on power usage to prevent brown outs. Building automation systems allow the owner to cycle various things off like water heaters or drinking fountains where use of these things will not be noticed even though they are off.
• DDC/building automation system (BAS) should offer the ability to send alarms via email, pager, or telephone to alert building managers and/or technicians of developing problems and system failures.
• Management companies who acquire a good DDC/building automation system (BAS) can have DDC set up to bill tenants for energy usage.
• DDC/building automation systems (BAS) should have the communications abilities to be integrated with other building automation control systems and TCP/IP. BACnet compatible or other open source communication protocol is a plus.

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