ASHRAE 135-2020

Meet Building Automation and Control Systems Communication Needs with Standard 135-2020. This product is only available as a PDF.

BACnet, the ASHRAE building automation and control networking protocol, has been designed specifically to meet the communication needs of building automation and control systems for applications such as heating, ventilating, and air-conditioning control; fire and other life safety and security systems; energy management; lighting control; physical access control; and elevator monitoring systems. The BACnet protocol provides mechanisms by which computerized equipment of arbitrary function may exchange information, regardless of the particular building service it performs. As a result, the BACnet protocol may be used by mobile and cloud-hosted devices, head-end computers, general-purpose direct digital controllers, and application-specific or unitary controllers with equal effect.

This protocol provides a comprehensive set of messages for conveying encoded building automation data between devices:
* Hardware binary input and output values
* Hardware analog input and output values
* Software data values
* Schedule information
* Alarm and event information
* Trend and event logs
* Files
* Control logic
* Application specific data for a large range of building services
* Network configuration including security

The 2020 edition of Standard 135 includes many new capabilities and several clarifications. New capabilities include lighting and elevator device profiles that provide a standardized description for these types of devices, along with audit reporting and logging to capture auditable actions. BACnet Secure Connect, a BACnet datalink layer, was also added. This datalink is fully compatible with all existing BACnet datalinks and provides an interoperable secure path for BACnet communications.