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New BACnet Standard Published

March 26, 2013
ASHRAE recently announced the publication of ANSI/ASHRAE Standard 135-2012, BACnet – A Data Communication Protocol for Building Automation and Control Networks.

ASHRAE recently announced the publication of ANSI/ASHRAE Standard 135-2012, BACnet – A Data Communication Protocol for Building Automation and Control Networks.

The standard was published ahead of schedule because of wide-reaching changes in alarming functionality in Standard 135-2010 Addendum af.

Addendum af provides significant improvements in alarm handling, including fault handling, temporary alarm-recipient subscriptions, and alarm distribution, Carl Neilson, chair of the Standard 135 committee, said.

“For building owners/integrators, these changes allow improvements in interoperability between lighting-control products and other building-automation systems,” Neilson said. “Hopefully, this facilitates more deployment and integration of smart lighting controls, such as lights that turn on/off when occupants enter/leave rooms, lights that come on based on the same schedules as climate control, and opportunities to reduce lighting based on energy usage during demand/response events. With the changes in alarming, we also hope to see alarming support in ‘smaller’ devices, which should provide more alarm and fault detection with a lower engineering cost.”

Addendum af:

• Removes annexes C and D.

• Clarifies optionality of properties related to intrinsic-event and change-of-value reporting; priority_array and relinquish_default; segmentation-related properties; virtual-terminal-related properties; time-synchronization-interval, backup, and restore properties; active_COV_subscriptions property; slave-proxy properties; restart-related properties; log_deviceobjectproperty; clock-aligning properties; and occupancy-counting properties.

• Ensures that pulse_rate and limit_monitoring_interval are always together and that event notifications are not ignored because of character-set issues.

• Adds the ability to configure event-message text, dynamically suppress event detection, specify a different time delay for to-normal transitions, inhibit the evaluation of fault conditions, and send only fault notifications for some objects types; notification-forwarder and alert-enrollment object types; and an event-detection enable/disable property.

• Separates the detection of fault conditions from intrinsic reporting.

• Makes event-reporting-property descriptions consistent.

• Identifies the property in each object that is monitored by intrinsic reporting.

• Changes the reliability-property description.

• Improves fault detection in event-enrollment objects and the specification of event reporting.

• Reduces notification-server requirements.

Standard 135-2012 also includes support for lighting control through a lighting-output object, the channel object, and the WriteGroup service.

The cost of Standard 135-2012 is $140 for ASHRAE members and $170 for non-members. Copies can be ordered by phone at 1-800-527-4723 (United States and Canada) or 404-636-8400, by fax at 678-539-2129, or online at

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Described by a colleague as "a cyborg ... requir(ing) virtually no sleep, no time off, and bland nourishment that can be consumed while at his desk" who was sent "back from the future not to terminate anyone, but with the prime directive 'to edit dry technical copy' in order to save the world at a later date," Scott Arnold joined the editorial staff of HPAC Engineering in 1999. Prior to that, he worked as an editor for daily newspapers and a specialty-publications company. He has a bachelor's degree in journalism from Kent State University.