by Patti Dees

Building automation and control network (BACnet) is a standardized data communication protocol. It focuses on data transfers for HVAC, plumbing, lighting and many other building systems. But why was it developed and how does it benefit you?

What is BACnet Protocol?

Data communication protocols ensure that data can be transferred between devices in a way that limits distortion or interference and maintains its usefulness on the receiving end. Protocols are beneficial in general because they allow for consistent data formatting, transfer and use.

BACnet is an open data communication protocol that standardizes data specific to building automation and controls. It is used across many types of systems including lighting, elevators, fire and security. The protocol specifies aspects of data communication including input and output values and formatting, error checking, control loops, schedules and hardware specifications.

This protocol is object-oriented. Information related to a device is classified based on standardized properties and has a unique identifier. Similar data is called an “object.” For instance, one object type is analog input. Message types or “services” define actions on the objects, for example “ReadProperty.”

Why Did ASHRAE and ISO Develop BACnet?

ASHRAE and ISO published BACnet in the ‘90s in response to a growing industry offering a great deal of promise that struggled with a key factor for success: interoperability. Without standardization, device manufacturers used or created protocols specific to their brands so that their products did not necessarily work with products from other manufacturers. They created proprietary divisions that complicated and limited the industry’s ability to expand as a whole.

Even though there was an increase in demand for automation, there was also risk for the building owners and contractors who drove that demand. Initial investment required owners be tied to a single manufacturer or they would need to invest in building gateways to coordinate the use of data from different protocols. Their options would be limited to devices which may not be the best fit for their systems. Not only would the systems be less flexible, they also would not be as cost effective.

The proprietary protocols also presented long-term concerns.  The lack of interoperability constrained upgrade options. If a manufacturer no longer supported the device or equipment under their proprietary protocol, either due to advances or the closing of their facilities, owners risked needing to completely overhaul their automation systems.

Benefits for of BACnet for Building Automation

Interoperability opens a range of possibilities for building automation. BACnet makes it easier to find devices that have the desired specifications for a more flexible system build. Multi-system integration does not require separate control stations. Owners are able to scale or upgrade their systems.

Another key characteristic of BACnet is its focus on building automation and control. The protocol was designed to include features with the building automation industry specifically in mind. Examples include alarm and event management, trends, as well as prioritized setpoint and output commands.

Current Standards and Compliance

BACnet is a national standard in over 30 countries, the US and Europe, and an ISO global standard. The ASHRAE Standing Standard Project Committee (SSPC) 135 updates the standard on a regular basis. Over the years, the protocol has expanded to cover advances such as web access and improved data infrastructure. The most current edition is Standard 135-2020 BACnet™ – A Data Communication Protocol for Building Automation and Control Networks.

Devices earn certification through the BACnet Testing Laboratory (BTL) after they are shown to be able to work with other BACnet devices. BTL maintains a list of BACnet Interoperability Building Blocks (BIBB’s). BIBB’s represent a device’s functions, supported objects and properties.

BACnet and Building Automation

BACnet’s forward-looking design helped grow the building automation industry and continues to support manufacturer innovation. It offers owners increased flexibility, interoperability and easier integration between building subsystems. These benefits support a more cost-effective automation system design and smoother day-to-day operation.

Patti draws on her background as a chemical engineer to share information with readers on technology, manufacturing and construction.