Very simply put, BACnet is a communications protocol that governs how your building automation devices work together. Think of it as a language: the rules that guide how devices communicate, just like vocabulary and grammar dictate how we talk to each other.
BACnet’s special because it’s a vendor-neutral standard. In the days before BACnet era (BBE), protocols were proprietary. Having devices from many different vendors in a single building was impossible, because those devices couldn’t communicate with each other at all: they just didn’t speak the same “language.”
So, you were locked into one vendor for the lifetime of the building. It was impossible — or at least, prohibitively expensive — to switch vendors. You couldn’t exactly replace every single device in the building. That unfortunately led to building owners and managers putting up with less than stellar service, or buying devices based on what was available to them rather than what was best for their system. This image by Peter MacDonald is a fantastic illustration of how challenging that period was.
Learn more about the history of BACnet in our whitepaper, “Why should you invest in BACnet?”
This all changed when a group of pioneers created a vendor-neutral, open standard. BACnet revolutionized the industry because it was suddenly possible (and downright easy!) to install devices from many different vendors. This video from Contemporary Controls is a great breakdown of what BACnet is and how it changed the industry forever.
For more information, this Quora post from Joel Bender gives a solid explanation, and this FAQ from Mike Newman also digs into the BACnet basics.