Determining and Stretching the Useful Life of Controls
By Rita Tatum - January 2011 - Building Automation
As building controls age, they develop glitches. So how old is too old? Here the experts vary widely.
McGowan says building controls have useful lives equal to or greater than the mechanical systems they control. "My primary recommendation to users is not to replace controls if they are functional," McGowan says. While he admits 15 to 20 years is aging, some "aging" controls may have more life in them than others. McGowan points out BACnet came into being in 1995. Those interoperable controls are likely to have more longevity than their proprietary counterparts, provided they have been maintained effectively.
Kirk Beaudoin, territory facilities manager of North America retail operations for Nike, says that the question of whether controls are aging depends on the product they are controlling. "A light switch could last as long as the building itself, while any controls tied to computers or software often are obsolete in five years," Beaudoin says.
"From a strictly obsolescence standpoint, controls are generally due for a face lift about every 10 years or so," says Althoff. However, less proprietary controls may provide another five years of functionality, because they are more flexible.
Sinopoli agrees. "Anything beyond 10 to 12 years is aging." Building controls, like all things electronic, tend to go through generations on a fast-track basis. "If there have been four upgrades in your building controls, it's like using Windows 98 now that Windows 7 is out," says Sinopoli. "You may run into problems trying to integrate with newer controls or getting a holistic view of your energy management use."
An Eye on Costs
In better economic times, replacing controls may be more easily argued in the boardroom. However, especially in today's uncertain marketplace, installing a hybrid control system is a less costly way to achieve some of the benefits of a full replacement.
According to Althoff, 20-year-plus pneumatic systems often continue to perform their tasks adequately. "They are workhorses that can be retrofitted at the terminal end to convert the air pressure to direct digital control (DDC), which gives you a type of hybrid control system," Althoff says.
In a hybrid controls application, the main valves continue to operate on pneumatic actuators. The pneumatic air signals are converted into DDC signals. These signals, in turn, receive and transmit data from zone thermostats, allowing tighter control in the building occupant's personal zone.
While better than doing nothing, that approach has its limits. "These conversions allow building owners and operators good zone control without tearing out their main systems," says Althoff. "However, they do not provide the same high level of energy conservation as a variable frequency drive that is controlled directly with a DDC signal."
Another way to justify building controls upgrades is by changing them over in affordable phases. This option works well in multi-building campuses, such as university and medical campuses.
Sinopoli cites a large hospital campus that was having operational problems with its legacy controllers. Late last year it began replacing its older controllers. As the project is extensive and the health care environment requires optimum functionality in its buildings, the hospital decided to do so in phases. "That way, they can schedule areas in a building, making sure they can be down for the time involved in replacing the older controllers with new ones without jeopardizing patient care," says Sinopoli.
When Less Is More
Some 15 plus years ago, Nike retail store lighting was designed for theatrical presentations, with dimming capabilities, strobe lights and music. As its marketing and presentation emphasis changed, the theatrics were abandoned but the lighting controls remained. "The existing controls in those stores was overkill," says Kirk Beaudoin, territory facilities manager of North America retail operations for Nike. "It was like using a jet to run to the supermarket."
And, like a jet, the controls systems needed considerable attention. Sometimes the lights and HVAC had to be shut off during business hours because the control system was down.
"We needed a simpler control system so that we could achieve cost savings in energy consumption, maintenance and repairs," says Beaudoin. Now, retrofitted stores stay comfortable and the lights remain on so consumers can continue to shop and, in turn, generate more sales of Nike products.
Now, with simpler controls in place, Nike is seeing 20 percent savings on utility bills simply by having controls turn off its lighting and HVAC systems during non-store hours.
— Rita Tatum