An XML/Web Services Addendum to ASHRAE Standard 135-2004, BACnet® was submitted for public review by ASHRAE committee, SSPC-135 as Annex M (BACnet/WS). Web services are a collection of technologies that allow different applications from different sources to communicate with each other without time-consuming custom coding. Because all communication is in XML, web services are not tied to any particular operating system or programming language.

The services described in Annex M provide a universal standard for data sharing, alarming, and trending of building data using XML and SOAP; providing a high level abstraction of building automation and control network data for use with other systems such as utilities, weather, and financial systems. Since this addendum includes normalized data types, it can also be used to bridge the gap between different building protocols including BACnet, MODBUS, LON® or even proprietary protocols.

As part of the BACnet Standard, this addendum permits BACnet to be used at every level of the information hierarchy from a sensor or controller to a workstation or server and now other enterprise systems using XML.

Already several manufacturers have started implementing the XML/web services per this public review addendum, and compliant building control solutions should be available within the next year after the addendum is approved.