Specifying BACnet: Key Is Understanding Facility Needs
The foundation of a BACnet specification rests squarely on the facility executive, who must ARTICULATE THE REQUIREMENTS of the organization
In some ways, large buildings are microcosms of Earth’s population. The systems in a building are varied and often have to interact with one another; but they usually speak different languages, and they rarely understand each other’s behavior. Fortunately, facility executives have open-protocol interoperability options available to them. Open systems “operate varied building subsystems on one workstation, and do so by using a language that all of a facility’s devices BACnet is short for Building Automation Control network. The American Society of Heating, Refrigeration and Air-Conditioning Engineers (ASHRAE) developed BACnet to help standardize intrasystem communication. First used in 1995, the communication protocol specifies a common language that allows components from disparate manufacturers to communicate.
The technology allows facility executives to unify myriad building systems without relying upon a single vendor, as is the case in proprietary protocols.
An understanding of BACnet is particularly important now, given the growing interest in building automation systems. BAS help users save time, money and operator hours. They can automate tasks, monitor power use or run operation reports to help identify cost-saving measures.
But purchasing a BAS is an expensive undertaking. The value of various automation system options – to the needs of an organization and to the job of the facility management team – must be carefully weighed. What’s more, the BAS must retain its value into the future. A BACnet-based open system brings important benefits when it comes to addressing both current and future needs.
One key benefit of BACnet is single-seat interface. The software allows control of multiple building subsystems from one workstation, rather than relying upon multiple workstations or separate software browsers to control each subsystem.
“BACnet makes diverse systems look like one,” says Jay Garbarino,a regional sales manager for Delta Controls. BACnet also provides vendor options. Unlike systems that use proprietary communication protocols, BACnet allows facility executives to choose between multiple BACnet-compliant suppliers to achieve the desired functionality.
The protocol also is an internationally accepted ISO standard – an important consideration for multinational corporations, which might, for example, want to integrate facility management in Asia with North American operations.
Roles Of the BACnet Spec Team
Putting BACnet to use requires the collaboration of many parties. Though the facility executive prompts its use and provides the details that build the specification, consulting engineers, product suppliers and systems integrators all have roles to play in turning automation needs into reality. Nevertheless, the foundation of BACnet specification rests squarely on the needs of facility management, and that set of needs must be precisely articulated.
Owners must clearly identify problems or activities that need to be controlled,” says Terry Hoffmann, global products marketing manager for Johnson Controls. “Facility executives must also prioritize these needs.”
Because those requirements are the basis for all that follows – including requests for device functionality, sequence of operations and myriad other considerations – facility execulives can best obtain the system they need by knowing their facility inside and out.
Owners and end-users must provide detailed requirements, needs and goals,” says Ed Merwin, director of field sales at Tridium. “They must review and comment on the spec, provide budget guidance and define the roles of each person who will be using the system.”
The role of equipment, control and automation vendors during the process is to provide accurate and complete technical information.
Systems integrators – a relatively new niche in the facility management field – are responsible for tying the various building systems into one functional too! for the owner.
Knowing and understanding a facility’s requirements is essential to successful BACnet integration. Day-to-day operations, the mechanical sequence of events within a building and the role that the facility management team plays are all critical bits of information.
“A spec is a means to an end,” says Merwin. The goals of an organization should be explored. The spec should include features and functions that support the organization’s mission.”
For facility executives, that requires outlining organizational objectives. “I’ve seen some specs written so that the facility could automate its irrigation,” says Larry Haakenstad, regional sales manager for Alerton. “If schools want to water their sports fields, BACnet can do that.”
Because BACnet is capable of coordinating communication with many subsystems, the possibilities are limited only by organizational needs.
“Some facilities will want singlebutton shutdown features,” says Jon Williamson. A product manager at Andover Controls, Williamson explains that such a procedure is an oft-sought safety measure. “Let’s say a fire signal goes off. BACnet can then enact a smoke-control sequence, turn on emergency lighting, start video recording or take other actions that a facility might find useful in an emergency.”
Such functions, Williamson explains, can be automated by BACnet upon an alarm, or the single-button feature can be enacted via an operator who assesses the alarm and determines the appropriate action.
Focus is key
Because BACnet can coordinate interaction between so many systems, one challenge facility executives face is choosing the features that are necessary and discarding those that would merely be “nice.”
Identifying the critical information needed from vital equipment is a good starting point, say experts, as is documenting day-to-day operations and answering one simple question: How can the facility executive best save time, energy and costs?
As a rule, a good specification also should use various organizational or equipment timelines as reference points. “Some items in facilities, like chillers, will last longer than a BAS,” says Amy Momsen, manager of controls marketing for McQuay.
Facility executives also need to be aware of timelines that may not be immediately clear. Where will the organization be in five, 10 or 20 years? And if a facility houses tenants, how might their needs change overtime?
An awareness of a facility’s future should also be considered by facility executives. Future plans for growth, personnel and budget constraints are important.
Investigate potential future technology, too. “If an organization knows that a building will serve its needs for 20 years, it’s important to ask whether the critical facilities systems – controls, fire, security, access control will be able to incorporate new technology at an affordable and controllable cost,” says Garabino.
That’s an important consideration for owners who have legacy systems in their facilities. Via gateways, BACnet can communicate with legacy systems,” says Steve Ferree, vice president of marketing for Fieldserver Technologies. “Getting rid of systems can be expensive. Sometimes facility managers really like or are used to certain systems, and the ability to incorporate those is a big benefit of BACnet.”
Experts also have recommendations on what does not make a good BACnet specification.
“I see specifications that refer to conformance classes that are no longer valid,” says Chris Hollinger, an integrated systems product manager for Siemens Corp. “And I see people who rely only upon templates and who throw in a number of BIBBs (BACnet Interoperability Building Blocks).
‘While templates are invaluable tools that help facility executives identify the features and functionality desired, they should not be used as the only means of building a BACnet specification. The result of relying solely on templates is a specification not tailored to an individual organization’s mission. And BIBBs should only be applied to the devices that require them.”
Device profiles are also important. “Specify BIBBs only for those parts of the system that need building blocks,” says Williamson. “A VAV doesn’t need the same spec as an air handler.”
Facility executives should steer clear of unnecessary specification stipulations. For example, one specification required certain actions be performed with a right mouse click when a left mouse click would have worked.
Experts also advocate searching out devices tested in the BACnet Testing Labs (BTL). “If the BTL has not tested and certified all of the equipment in a system, like gateways, servers and clients, ensure that the system will work with acceptable performance and functionality,” says Roy Kolasa, Honeywell’s integrated solutions market manager.
Finally, developing a solid specification includes watching for contradictions, says Hollinger.
Because they know their facilities best, the onus rests on facility executives to provide a list of interoperable equipment and subsystems. According to Kolasa, this list should include subsystems and infrastructure drawings showing networks and distribution busses available for the enterprise system.
Experts also say facility executives should list specific functionality expected from the master system, including system points and functionality for control, scheduling and alarming from the master system.
Kolasa suggests examining goals for a facility over a five-year period. Those goals should include energy optimization, equipment cycle-time improvements, personnel productivity and improvements in general building productivity,” he says.
Before specification writing begins, facility executives need to communicate special considerations.
“We heard a K-12 buildings and grounds superintendent criticize a spec for putting operable thermostats in the hallways of a high school, fearing that students would tamper with them,” says Randy Amborn, senior marketing specialist at Trane. “While the system designer should have considered this, the school district did not specifically communicate that hallway thermostats would present a problem.”
Another mistake to avoid is not looking beyond the needs of the facility management team.
‘Talk to IT guys if you want to access information remotely,” says Momsen of McQuay. Installing BACnet is possible without help from the organization’s information technology department, but, depending upon the specification, involving an organization’s IT department can smooth BACnet’s use. “Firewalls let e-mail through, but if you want to access equipment directly and remotely, you’ll have to get some help from IT,” Momsen says.
She also suggests that facility executives with operations in distant locations investigate putting modems on control panels of large equipment, such as chillers.
Facility executives should also determine the best way to share information between team members once a BACnet system is in place. Photos of problems can be e-mailed or posted to an intranet page to which everyone on the facility team has access.
Hoffmann of Johnson Controls suggests collaborating with executives in other organizations to review specification needs. Talk to peers in some kind of forum,” he says. he suggests that facility executives turn to professional associations or conferences and trade shows. “Look for people who’ve faced similar challenges in their facilities,” he says. “Ask them if they’ve missed any features.”
Hoffmann also suggests visiting sites with comparable facilities that use BACnet to discover what’s needed.
Whatever the path to BACnet specification, experts offer one standing suggestion: Facility executives must be very detailed and honest about an organization’s facility needs, and use device functionality as the ultimate measure of the value of BACnet.
“Focus on the outcome,” says Garbarino, “not on the verbiage.”
Copyright Trade Press Publishing Company May 2004
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