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Moving forward with BACnet

What is BACnet?

In 1987 the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) recognized the need for a standard method of communication between proprietary devices in the heating, refrigeration, and air-conditioning industries. Similar to the situation in industrial controls and automation, users were unable to specify devices from different companies into a single system, because of communications incompatibilities. The result of the desire to standardize communications was the development of BACnet (Building Automation Control network).

BACnet is a data communication protocol, also known as ANSI/ASHRAE standard 135-2008 and as the international standard ISO 16484-5.

A great article about BACnet was published in 1997 in the journal Heating/Piping/Air Conditioning Engineer. An updated version of that article is available on the BACnet website (

BACnet, like many other protocols, is based on the client/server model. BACnet messages are called service requests. In BACnet, the client sends a service request to the server device, which performs the requested action and reports the result back to the client. BACnet currently includes 35 message types divided into five classes. The various classes of service requests deal with different types of messaging. For example, one class handles alarms and events, while another deals with uploading and downloading files. The BACnet website lists several tutorials ( helpful to gaining a deeper understanding of BACnet and its application.

BACnet Today

Today, BACnet is a standard accepted around the globe: It is a national standard in more than 30 countries, as well as the U.S. and Europe, and an ISO global standard. The protocol is supported and maintained by ASHRAE Standing Standard Project Committee 135. The official website of BACnet is, where you can find information about BACnet including news, organization activities, and BACnet publications.