BACnet: Salvation or Promise?
BACnet: “The global standard for building automation.” This not-so-new technology, still evolving, continues to generate expanding interest among the major suppliers of systems generally categorized as building control systems.
is an acronym for “B
utomation and C
etwork.” The list of systems that it is capable of linking includes HVAC controls, fire system devices, lighting, security, and even certain elevators. According to H. Michael Newman, a pioneer in this technology and original chair of a BACnet-focused ASHRAE committee, the benefits of this technology include improved data sharing among vendors of building control systems — creating less need for multiple operators — and enabling improved event management and scheduling. Developers published the original standard in 1995, resulting in the approval of ISO Standard 16484-5 in 2003. They anticipated a high likelihood of success, for the following reasons:
The Original Goal
- User demand,
- no fixed architecture,
- independent of current technology, and
- broad participation in its development by most of the major vendors.
The original goal was to develop a bridge that could accept data in both analog and binary formats. It had to be able to operate with a variety of operating systems and interface with various types of networks.
Naturally, it had to be not only accepted, but also embraced by the historically pertinacious manufacturers and suppliers of numerous and extremely diverse systems. They had to agree to “map” their devices to BACnet protocols, which had to be established by consensus. This required a significant shift in thinking for some of the “big boys” in the controls industry.
Since the invention of control systems, we were essentially hogtied by the suppliers of those systems. We had to choose between two options, neither of which was totally attractive. Some of us decided early on to stick with one vendor, after which we had to sole source new installations or upgrades, and always felt exploited in the process. Others among us, either by policy or conscious decision, went to the other extreme by electing to avoid sticking with a single supplier — ending up with a multitude of systems in our buildings. That decision may have saved money up front, but ended up costing more in the long run, since there would be no central location where all systems could be monitored. Add to that cost the implications associated with additional training, maintenance contracts, and parts inventories.
BACnet’s most attractive feature is the prospect that campuses with a single dedicated system in more than one building, or with more than one system in one building, can enjoy much enhanced flexibility in the procurement of new or additional systems. As mentioned above, many of the suppliers whose names we all know (if not love) have done a 180° turnabout. They will now speak a common language! Since BACnet is able to have its routers talk to each other over the Internet, the number of individuals required to monitor diverse systems can be smaller than was historically the case. Moreover, as BACnet has moved from the manufacturer test environments to real life installations, any shortfalls or compromises contained in the original specifications are starting to get corrected. End users and building owners are exerting their newfound power to move to a new provider if their chosen BACnet supplier does not provide adequate service and support for their products.
Predictably, there are downsides. One of the more significant ones is that today’s BACnet will only support operators in their efforts to manage routine tasks such as trending, scheduling, changing set points, and managing alarms. Since a committee of vendors designed BACnet protocol, it follows that each of them preferred to maintain some level of control over customers. They achieved this objective by requiring users to rely on them if any program changes are required, such as when HVAC equipment being monitored is switched out. Another notable detractor is the initial cost of converting to BACnet. It is not a plug-and-play technology. Initial costs for conversion from existing systems can be intimidating, lending this implementation more readily to new facilities.
Technologies are evolving which will provide a less expensive alternative by invoking serial servers and certain “open” devices to bridge existing technologies from the major control system suppliers into a single supervisor, still relying on BACnet as the final conduit. The challenge here is the difficulty in gaining access to protocols and proprietary communications, until recently tightly controlled by suppliers. This list of participating suppliers is fortunately also growing, ultimately holding the promise of reducing, or at least deferring, the cost of replacing existing peripherals.
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Pete van der Have is an independent educational facilities consultant with Facilities Engineering Associates, located in Fairfax, VA. He can be reached at firstname.lastname@example.org.