Building Automation Systems | HVAC Control
What you will learn from this article:
1) the efficiency and conveniences Building Automation Systems add to a building
2) how Building Automation enhances energy savings and troubleshooting problems
3) how allowing controllers to communicate with each other enhances HVAC and electrical systems
4) many of the benefits of building automation systems
5) Resource and Related Links to help you learn more
Many people wonder what Building Automation Systems (BAS) do. BAS is mainly used in commercial HVAC control systems and energy management system applications. Building Automation itself is an energy management system which saves management companies and building owners by efficiently controlling air conditioning and heating comfort and process systems. BAS 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 BAS controllers themselves do not need a computer to process the control functions as the controllers have their own internal processors.
Related Link: Learn more about DDC control loops (opens in a new window)
Building Automation Systems – Engineering the Controls
A set-up in a multi-story automated building would have many building automation controllers serving different types of air conditioning and heating equipment (BAS is not limited to just HVAC applications). Every building is different and it is important for the BAS engineer to select the proper HVAC control system and programs to control the various types of HVAC systems in a particular automated building. For building automation systems to be effective, it is important that the BAS systems are installed and tuned properly. Some advantages of a good building automation system are:
- Building Automation Systems (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.
- Building Automation Systems (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.
- Building Automation Systems (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.
- Building Automation Systems (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.
- 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.
- Building Automation System (BAS) should have such BAS control algorithms as reset schedules for heating plants, static pressure control, and other systems where energy savings can be realized through these predictive programs.
- 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.
- 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 building automation system (BAS) can have BAS set up to bill tenants for energy usage.
- Building Automation Systems (BAS) should have the communications abilities to be integrated with otherbuilding automation control systems and TCP/IP. BACnet compatible or other open source communication protocol is a plus.
There are many other examples of how building automation can help you especially if you manage large building(s) even if the buildings are next door to each other or on the other side of the world BAS can be linked to a central computer over the internet. If I’m a corporate engineer in Dallas and there are 25 buildings all over the states I can monitor and control all those buildings from any computer with an internet connection. It only gets better as time goes on but modern building controls are helping reduce energy usage and enhance buildings by making the electrical and mechanical systems smart.
The video below is a futuristic look into how building automation systems are developing for the next generation building automation systems.
Building Automation Systems – Resources
Related Link: Learn more about Direct Digital Controls and examples of programming or you can also see our Direct Digital Controls category
For another resource on Building Automation Systems click here.