Many, if not most, large commercial buildings have a building management system or environmental management system controlling and monitoring the HVAC system. These BMS and EMS use BACnet as their basis of communications. The newest versions of the energy codes are requiring the addition of advanced lighting controls with alterations, and energy benchmarking for existing buildings is being required by many cities and some states. These factors provide an opportunity to bring lighting and other building systems under a “single pane of glass” for control and monitoring.
The following is a Q&A with Scott Ziegenfus, manager of government and industry relations at Hubbell Lighting and a 2015 BACnet International Leaders of the Pack award recipient. He explains what’s new related to BACnet and why it’s important.
Q: What is BACnet?
A: ASHRAE created BACnet as an open protocol with all building automation systems in mind. The BACnet committee’s first official meeting was in 1987 and was solely focused on HVAC. Other systems, like lighting, were not really a consideration until much later; the Lighting Working Group did not have its first meeting until 2001. However, it has been realized over the years with an emphasis on commercial building energy use that lighting and HVAC make up two-thirds or more of the electrical energy of most commercial buildings. Bringing these two building systems along with others, like life safety and access control, under one umbrella or point of control makes sense. So many large commercial buildings already have BMS or EMS systems in place and evolving to BACnet is a natural choice.
Q: Why is BACnet important?
A: BACnet is required for lighting to be brought under the BMS or EMS system umbrella. With the evolution to LED and the intelligence of connected lighting technology, lighting systems can now share a tremendous amount of information that can be used by the BMS or EMS. Occupancy status, temperature, daylight and solar radiation, power consumption and indoor positioning are just some of the information that can be of value to other building systems, and that information is all communicated using BACnet objects and services as the common language.
Q: Are there any challenges?
A: The challenge lies in ensuring that specifications effectively communicate the owner’s intent about how systems like lighting should work in a controlled environment. The good news is that a fundamental shift is happening in BACnet to make specifying easier without the need for a Ph.D,-level understanding of BACnet. The solution lies in a brand new “family” approach to device profiles.
Q: What is the family approach?
A: The easiest way to specify product for BACnet is to specify a BACnet device profile that is listed in the standard. Particular device profiles have a minimum group of BACnet services to match the task. For example, if you want main control software you could spec a BACnet Advanced Work Station. This will ensure the minimum set of BACnet services needed to be effective is inside. However, because all device profiles were HVAC-based in the beginning you may encounter a scenario where a different system, like lighting or access control, has to “shoehorn” its unique products under the HVAC device profile. To make specifying easier for individual device profiles a new landscape of families has been categorized into the following:
- Traditional Operator Interfaces
- Lighting Operator Interfaces
- Life Safety Operator Interfaces
- Access Control Operator Interfaces
- Lighting Control Stations
- Traditional Controllers
- Lighting Controllers
- Life Safety Controllers
- Access Control Controllers
Q: So it’s like ordering off a menu at a restaurant. Why is this important?
A: You can choose any or choose all. This allows those systems that want to narrow their scope to do exactly that. A workstation can concentrate solely on a traditional HVAC-based device profile and that would be perfectly acceptable. But if that workstation wants to be everything to every system—lighting, access control, life safety—it can also do just that. A major but unexpected benefit is the family concept makes it easier for building automation systems, like lighting and access control, to use BACnet as its primary protocol regardless if they are connecting to a building management system.
Q: What can I do to support BACnet?
A: Your specification devices must conform to the new system or provide that they can demonstrate they achieve the same sequence of operation using traditional BACnet device profiles.