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©2015 This excerpt taken from the article of the same name which appeared in ASHRAE Journal, vol. 57, no. 6, June 2015

H. Michael Newman, Fellow/Life Member ASHRAE

About the Author
H. Michael Newman is manager, Building Automation and Control System Integration, Infrastructure, Properties and Planning – IT, at Cornell University, Ithaca, New York. He was Chairman of ASHRAE SPC 135P, SSPC 135, 1987 – 2000.

Celebrating BACnet’s success is nothing new for true “BACneteers”—but 2015 is special. This year BACnet committee members, developers, implementers, installers, building owners, operators, and everyone else who has benefited from the protocol, will be celebrating the 20th anniversary of BACnet’s adoption as ANSI/ASHRAE Standard 135. It has also been a bit more than 10 years since BACnet was embraced internationally as ISO Standard 16484-5 and then as a national standard in Europe, Asia, and other parts of the world.

The question is “How has BACnet done it?” How has BACnet managed to survive and thrive while many other protocols have come and gone? This article will look at some of BACnet’s success factors and present brief descriptions of some of BACnet’s features that have evolved over the last 20 years.


BACnet Success Factors

Here are the main reasons that BACnet is still around today:

  • BACnet was designed specifically for buildings. While the original BACnet committee, SPC 135P, initially focused its attention on HVAC, we always had in mind that nothing should be done to preclude its use with other kinds of building systems. Today, BACnet supports lighting, life safety and security, physical access control, elevators, etc., and the committee is always looking for ways to extend BACnet into other areas such as, for example, emerging “smart grid” systems.
  • BACnet was designed to be extensible. From the very beginning, those who were opposed to the development of a standard asserted that it would necessarily “stifle innovation.” To prove the nay-sayers wrong, nothing was adopted by SPC 135P unless, and until, we could convince ourselves that innovation would not be affected. Although this was sometimes a great challenge, the passage of time has shown the validity of our choices. BACnet is not only readily extensible, almost always in a backwards compatible way, but has continuously evolved to meet today’s communication requirements while embracing the new technologies that we knew would be coming along, even though we didn’t know at the time what they would be.
  • BACnet has never depended on any particular hardware or network technology. In fact, we studiously avoided any mention of networks or transport mechanisms until the basic communication structure, BACnet’s objects and services model, had been agreed to. This, coupled with the use of the well-known ISO-layered communication model,1 allowed us to use, in principle, any kind of network that we wanted. We picked ones that were in common use at the time (ARCNET, Ethernet, EIA-232, and EIA-485) and that were acceptable to the manufacturers because they were already familiar with them. While some protocols are stuck with old chipsets, BACnet has been able to embrace wireless communication, the Internet Protocol (IPv4), and even the latest IPv6 that will probably be a key component of the so-called “Internet of Things (IoT).” More on this later.
  • BACnet has no fixed communication architecture. All the devices can be peers of each other in a “flat” arrangement or arranged in “hierarchies” depending on the needs of the systems being interconnected.

Read the Full Article


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