Laying the Groundwork for Open BAS Systems

understanding the basics of the bacnet protocol can help facilities executives tap its potential

By BOM Editorial Staff  

BACnet is a good example of necessity being the mother of invention. Back in the mid-80s, Michael Newman, then the facilities manager at Cornell University, wondered why he needed a separate communication protocol for each piece of building automation and controls equipment in his facilities. His frustration unknowingly started the ball rolling on a path that would lead to systems interoperability.

Today BACnet makes it possible for a diverse range of building systems to interoperate, which can lead to increased efficiency and flexibility in a BAS. But to leverage the BAS for maximum benefit, facilities executives have to do more than just ask for BACnet-compliant systems. Facilities executives need to consider overall goals for the facility, and how interoperability can help support those goals. This means evaluating the BAS and identifying aspects that could benefit from more open communication. The first step, though, is understanding the basics of BACnet.

The simplest description of BACnet — which stands for Building Automation and Control Networks — is that it is a standard communication protocol, or language, developed by ASHRAE to allow different automation and control equipment in a facility to share data and commands. Mark Bergman, director of controls, McQuay International, likens it to the World Wide Web.

“Your Web browser, through common protocols, allows you to access a variety of things, independent of your PC or operating system, because it has all been facilitated by standards,” says Bergman. “BACnet allows you to do the same thing with building systems.”

One of the primary benefits of a standard communication protocol is operational efficiency. Without a standard protocol, each piece of equipment communicates using its own proprietary protocol. For facilities executives trying to build “best-of-breed” systems, this can result in a lot of headaches, as well as a lot of money spent enabling separate pieces to work together.

“Facilities executives want to be able to design systems using best-of-breed components, and no one manufacturer builds the best components for every aspect of building controls,” says Tom Zaban, vice president of sales and marketing, Reliable Controls. “A chiller system may come with its own packaged controls system, while the rooftop unit is from a different manufacturer, and the VAV controls are from another manufacturer. You want all the units to communicate with each other.”

Beyond Gateways

In the past, the solution to this problem was gateways — specific protocols that allowed one piece of equipment to communicate with another piece of equipment, either from a different manufacturer or a different generation model from the same manufacturer. The problem was that a gateway was expensive for facilities executives and manufacturers alike, was only designed as a bridge between two distinct proprietary protocols, and would only allow a limited amount of information to be transferred. If a facilities executive bought a gateway to connect two pieces of equipment, then wanted to connect another piece of equipment that used a third proprietary protocol, an additional gateway was required.

The BACnet protocol was developed as a response to this problem. It was designed as a standard protocol that would enable each piece of equipment to communicate with every other piece of equipment, regardless of manufacturer or generation. This common method of communication made operations within the BAS more efficient, and also gave facilities executives flexibility when making purchasing decisions.

“BACnet allows the different aspects of your system to work together,” says Bill Swan, Chairman of ASHRAE Standing Standard Project Committee 135, which is responsible for BACnet. “It also allows you to take some part of your building system and replace it with something from another manufacturer.”

This flexibility is an important benefit of an open protocol and can help facilities executives avoid being stuck with a single vendor.

“Users don’t want to be locked into one vendor,” says Mike Olson, manager of HVAC applications, ABB. “This is one of the driving points behind BACnet— end users don’t want to be boxed in.”

By allowing equipment to communicate using a common protocol, BACnet creates a level of equity among different manufacturers’ products. Zaban calls it a “horizontal market,” in which products from several manufacturers are on the same plane, as opposed to a vertical arrangement, in which facilities executives have to rely on a single manufacturer for all their equipment needs because existing equipment uses a manufacturer’s proprietary protocol.

“Overall, it gives more freedom and autonomy to the facilities executive,” Zaban says.

Speaking the Same Language

BACnet enables a facility’s automation and control systems to communicate using a common protocol. As a result, all information about the system can be accessed from a single screen. This open view is another benefit of interoperability, and one that can streamline data-gathering and problem-solving.

“Without interoperability you have multiple software packages with user interfaces that don’t talk to each other or share information,” says Chris Hollinger, product manager, Siemens Building Technologies.

Hollinger gives an example: A space in a building is not receiving the proper amount of cooling. This could be the result of a damper not working properly or a poor-performing chiller. Traditionally, diagnosing the root of the problem would involve gathering data on each piece of equipment from separate sources, which could be time-consuming. With an interoperable system communicating on a standard protocol, all the information can be accessed from a single workstation, so the cause of the problem can be narrowed more quickly. This ease of access has the potential to simplify many aspects of a facilities executive’s job.

“It used to be that facilities executives would have to go to a number of different rooms and fiddle with everyone’s systems to change anything,” says Bill Wilde, vice president of communications, KMC. “The benefit of interoperability is that you can manage everything from one spot without having to go to every manufacturer’s protocol and figure it out.”

The Next Level

Although BACnet allows systems to share information and communicate in a common language, experts caution that it should not be considered “plug-and-play.” Specific areas of interoperability need to be defined, and it’s important that facilities executives understand this when considering BACnet.

“Some people assume that, because BACnet is a standard protocol, it is plug-and-play,” says Brian Dutt, vice president of marketing, Delta Controls. “But building automation systems still need to be engineered. True interoperability requires good planning.”

BACnet allows for systems to communicate in a number of areas, including data sharing, trending, scheduling, alarm and event management, and device and network management. The types of communication a specific BACnet system will allow are determined by the facilities executive and the goals for the system.

“BACnet can just share data, but it becomes more powerful when you can share schedules, trends and alarms,” says Jon Williamson, senior product manager, TAC. “Facilities executives need to determine what systems in their building need what level of interoperability and make sure BACnet equipment provides that interoperability.”

Dutt agrees, and says it’s important to recognize that BACnet is essentially a communication tool.

“BACnet allows products from multiple sources to be used together,” he says. “It does not remove the need for an application engineer to design and configure the automation system.”

Where to Start

For facilities executives interested in implementing the BACnet standard protocol, experts say it’s important to consider the goals for the system first. Identifying what the facilities executive hopes to achieve from interoperability will determine the specifications used, says Greg Turner, director of global offerings, Honeywell. This may require some homework, and some time spent learning about the technology and how it can be applied to the facility’s needs, says Marc Petock, director of marketing and communications, Tridium. However, it doesn’t mean the facility executive needs to become a controls expert.

“At the facilities executive level, it’s important to keep the focus on what you want interoperability to do and not get bogged down in the implementation details,” says Steve Tom, director of technical information, Automated Logic. “Don’t try to write a building automation specification based on the ASHRAE handbook.”

Working with in-house or consulting engineers and trusted vendors can help. “Find vendors you can trust, and consulting engineers who are reliable,” says Terry Hoffman, director of marketing for building automation systems, Johnson Controls. “Having the right people around you will help in being able to define what you need in a facility.”

Working with these groups will help determine the details of the functions the system will be expected to perform. As part of the process of analyzing requirements, facilities executives should take the time to understand the needs of the teams that will be using the various systems, says Sharon Dinges, system application engineer, Trane.

It’s important to have a clear definition of functional details when it comes to bidding time, says Hollinger. Writing down everything that you want out of the system can be a good way to make sure that everyone involved in the specification and bidding process maintains a clear view of the end goals.

“It is incumbent on facilities executives to give a clear vision of what they want, and they need to reflect this in a written document,” says Zaban. “It doesn’t have to be hugely complicated, but it does need to be articulated and specified.”

After goals for the system are established, ensure that vendors will be able to accommodate the specifications. According to Swan, facilities executives should use the same rigor in making sure the equipment will meet their goals as they do in laying out the goals for interoperability. One part of this is asking whether equipment has been BACnet Testing Laboratories (BTL) certified. This certification ensures the equipment has been tested to interoperate on the BACnet protocol.

“BACnet is very flexible, but different manufacturers use flexibility differently,” says Swan. “BTL has laid out rules to guarantee interoperability.”

Overall, the role of the facilities executive in implementing a BACnet system is determining what can be gained from interoperability and articulating this to the engineers and vendors that will be able to build specifications into the products.

“Decide what your interoperability goals are, and make sure the engineer understands what the goals are,” says Tom. “Stand behind the specs when working with vendors.”

A Work in Progress

As BACnet continues to see widespread use, the scope of interoperable systems continues to expand. Experts say one of the biggest misconceptions about BACnet is that it only applies to HVAC equipment. While the roots of the protocol are with HVAC systems, current standards are being developed for lighting and access control systems, and an early draft of an elevator controls systems standard is in the works.

There is also a standard in development that enables BACnet to utilize Web services to communicate with other enterprise management systems, for example, accounting and human resources. These systems are not a part of a building’s automation system, so traditionally it has not been possible to share information with them. By extending BACnet’s communication capability to the Web, it will be possible to share information with these systems, and thus further take advantage of interoperability.

One possible application of this expanded interoperability could be integration with energy utilities.

“The utility would tell you what energy will cost in the next 24 hours, and the facility would be able to use energy accordingly,” says Swan. “You could cool water at night when it’s cheap, and use it the next day.”

Experts predict that BACnet will continue to evolve and be able to incorporate more and more technologies, further enhancing interoperability possibilities for facilities executives.

“It’s important to recognize that your building may have needs you don’t recognize now,” says Randy Amborn, marketing communications manager, Trane. “Having systems that support an open protocol gives you options for the future.”

By building a BACnet base, facilities executives become better able to take advantage of future opportunities for operational efficiency. And the more efficient the system, the more efficient facilities executives can be.

“Facilities executives are like the conductors of orchestras,” says Wilde of KMC Controls. “They have to manage multiple systems and environments and make sure everything works in harmony. BACnet makes things a lot easier to control.”

About BACnet International

BACnet International is an organization made up of manufacturers, systems integrators, installers, consulting engineers, end users and software suppliers that aims to accelerate adoption of the BACnet protocol through increased awareness and education. The organization was formed by the merger of the BACnet Manufacturer’s Association and the BACnet Interest Group of North America. According to Andy McMillan, President of BACnet International, the merger represented a significant step in the evolution of the BACnet community.

“BACnet International is a group designed for both users and manufacturers,” he says. “As the BACnet industry matured, it was clear there was value in combining the two to better support and extend the BACnet community.”

The mission of BACnet International, says McMillan, is to support people in implementing and extracting value from BACnet. This includes educating users and specifiers about BACnet, which is one of the major goals of the BACnet Conference and Expo. The first-ever conference will be held in May in Phoenix, Ariz., and will include educational sessions as well as a product expo to give users a first-hand view of BACnet’s capabilities. BACnet International, under the auspices of its Steering Committee, is also working to develop mechanisms that would enable groups of users to come together and share experiences and advice.

“BACnet International can provide a forum for facilities executives to network with each other and develop a consensus view of what products and standards enhancements they’d like to see next,” says McMillan. This consensus view can be used as a guide by standards organizations, manufacturers and software suppliers as they plan their future development efforts.

The BACnet standard has achieved acceptance by the International Organization for Standardization (ISO), says McMillan. As such, BACnet International is establishing liaisons with BACnet Interest Groups around the world, including those in Europe, Russia, Japan, Australia and China.

In addition to promoting education, BACnet International manages the BACnet Testing Laboratories (BTL) as a way to ensure products built for BACnet will interoperate according to the standard. BTL provides an online list of all products that have been tested, and McMillan says this is a good resource for users to find out about different products, and to confirm that products of interest to them have been independently tested for conformance to the BACnet standard.

“The purpose of testing is to make sure all manufacturers are using the same interpretation of the standard,” says McMillan. “For users seeking smooth integration, it’s one more piece of the puzzle.”

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  posted on 4/1/2007   Article Use Policy

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