BACnet Legacy Migration Can Ease With an Older BAS
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Inevitably, every facility reaches a point where the existing building automation and control devices — the legacy systems — need to be upgraded or replaced. This may be because of obsolescence or rising repair and maintenance costs. It might also reflect a desire on the part of the facility executive to move to open systems to take advantage of interoperability’s benefits.
“Customers expect a centrifugal chiller to last 25 years or more, but today, you get a controller that has a circuit board that can’t be produced after seven to 10 years,” says Mark Bergman, director, McQuay Controls. “Thanks to open protocols, you don’t have to throw away functional equipment simply because digital controls have become obsolete. Much of today’s new design is backwards compatible and seamlessly integrates older systems into the newest building automation systems.”
Legacy migration is the orderly changeover of existing building management and control systems from older technologies, usually those using proprietary protocols. Through that process, facilities professionals can integrate new networks, devices and programs into the building by operating on a standard protocol like BACnet.
“Legacy migration to BACnet provides owners with an opportunity to expand and replace systems as required in a strategic manner,” says Terry Hoffmann, director of building automation systems marketing at Johnson Controls. “Applied correctly, it allows them to get the maximum use out of their existing systems while taking advantage of the latest advances in system design.”
The primary benefit of migration — as opposed to replacement — is the deferred cost of controls and equipment, as well as such deferred costs as hardware and software tools and equipment inventory. Migration extends the life cycle of existing equipment while defining a path to a new system.
“Dollars saved through legacy migration can give facility managers more flexibility in light of shrinking budgets and increasing energy costs and provide funding for building automation system roadmap planning and necessary IT infrastructure improvements,” says Roy Kolasa, open system integration market manager for Honeywell global offer management.
Bergman says that upgrading legacy systems also positions buildings for easier upgrades and even small incremental improvements down the road. Upgrading can also can yield better return rates on equipment. The switch for those operating older systems is almost inevitable – and smart.
“It makes a lot of sense,” says Brian Dutt, vice president of sales and marketing for Delta Controls. “Repair and service parts may be either too expensive or unavailable. Finding qualified technicians who can work on the system may become difficult. The more you invest in the older equipment, the more dependent upon a proprietary solution you become. It simply gets too expensive. Migrating from that existing system is getting easier all the time.”
Legacy system migration requires systematically changing out the network connectivity device — informally known as a “brain transplant.”
“You’re leveraging the existing infrastructure and taking the original ‘brain’ out of the device and putting in a control that communicates through BACnet,” says Ron Poskevich, general manager of Lumisys. “The least expensive part of a system to replace is the brain. The ‘brain transplant’ leaves the most expensive part, the existing infrastructure, in place.”
Legacy migration also can be achieved by adding a distributed bus gateway or router capable of communicating over IP to front-end clients and to the legacy distributed control bus, which may be a proprietary protocol.
As Chris Hollinger, senior product manager at Siemens, points out, legacy migration is not an all-or-nothing proposition.
Facility executives can take a relatively measured approach to the process. “Always try the step-by-step approach first, versus assuming you need to rip out and replace everything,” he says. “What is still operating properly might very well be able to be preserved.”
It’s important for facility executives to understand the economic rationale for legacy migration.
“The justification should come from the fact that a very antiquated and less-capable system may be replaced by something much more capable,” says Todd Cowles, sales manager for Trend, a division of Honeywell. “If an upgrade is justified, the owner might as well choose one with BACnet capabilities for the sake of flexibility in the future.”
There are several reasons to specify a BACnet system, says Bill Swan, buildings standards initiatives leader for Honeywell, Alerton and Trend Control Systems. “First, the element of ongoing competition eliminates the problems that may come with being ‘locked-in’ to a single manufacturer,” Swan says. “Second, the synergies possible with integrating disparate systems increase the number of strategies available for reducing energy consumption. Third, a BACnet system allows the system integration of new strategies currently in development or others not even considered today.”
A systems integrator can facilitate connecting existing systems to a new, single-seat solution like BACnet that will aggregate information from the old systems, while providing an open platform for moving forward in managing the facility. Choose an integrator with a proven track record in similar expansions or integrations.
“Make sure you get a full understanding of what will communicate and what will not,” says Jon Williamson, product manager for TAC. “Furthermore, find out to what level. Some migrations allow you to preserve your past investment while still transitioning to the future. Be certain to know how the old product will work with the BACnet system. If the old controllers have only a limited BACnet connection, then it simply may be better to replace them.”
During the planning process, also pay close attention to the workstation/user interface recommended by the integrator. It is one of the most important purchasing decisions facility executives will likely face during legacy migration. The interface is the one element in the system that will remain constant for years down the road.
During the legacy migration initiative, new buildings, expansions and renovations might be awarded to different vendors based on performance and price, but the central software will need to work with whatever product is chosen.
“Most of the challenges with this migration come into play later if there is no strategy in place with short-, mid- and long-term goals for the operation and maintenance of the facility,” Hoffmann says. The plan should provide the basis for budgeting as well as a scorecard for measuring progress.
Hoffman calls the plan a “living document,” which should be reviewed and updated regularly as changes occur in systems technology and service levels or as needs change on the facilities master plan or corporate strategic plan.
“When specifying a BACnet system, also specify that the devices bear the BTL Mark,” Swan says. “This ensures that the devices are conformant with the BACnet standard and can be equated to say, ‘plays well with others.’” The BTL Mark is issued by the BACnet Testing Lab in the United States. WSPLab is the testing lab for BACnet in Europe.
Facility executives should have a plan for maintaining the legacy equipment as long as it is intended to be operational. Many legacy systems are not supported by their original manufacturers, which may have left the business or have been acquired by another company that has lost interest in maintaining the brand.
Experts say a major benefit of selecting BACnet for the legacy migration is that it allows owners to choose the equipment that is “best of breed” and provides the greatest value. Savvy end users identify a core set of technology providers and stick with them unless major changes occur in their performance.
“Facility executives are not locked in to a single manufacturer,” Poskevich says. “Multiple options are available, offering flexibility that addresses the needs of each building. This ‘best of breed approach’ gives the owner or operators the ability to connect to distinct systems in different buildings and have them communicate and work together.”
BACnet Legacy Migration Can Ease With an Older BAS