Lighting Controls Strategies Can Save Money
July 2010 - Lighting
Bear in mind that lighting upgrades go beyond lamps, ballasts and fixtures. To further increase efficiency and savings, controllable lighting is not just something that's "good to have." It's a necessity for creating a truly efficient lighting system. However, as important as lighting controls are for energy savings, most facility professionals still have not implemented a facilitywide controls system in their buildings.
"With only 1 percent of buildings using controls, this is often one of the most overlooked, yet most effective, technologies in saving energy through lighting," Casanova says.
Upgrading to lighting controls can save as much as 50 percent of the energy used in a commercial building, says Bob Freshman, marketing manager for Leviton Lighting Management Systems. "This can amount to a very significant saving on energy costs," he says. "And the dollars saved only will increase as the cost of energy rises."
In fact, statistics from the National Electrical Manufacturers Association (NEMA), through its enLIGHTen America (www.nemasavesenergy.org) campaign, estimate the use of lighting controls can reduce energy costs by an additional 15 to 80 percent, depending on the facility, over and above savings from other lighting upgrades alone. Some estimates assume that with no lighting controls in place, the energy savings from a lighting system upgrade should be a minimum of 30 percent, but if control options are part of a system, it could easily reach 50 percent.
"Numerous strategies must be combined to deliver a high-performance building, but none is more powerful than a thoughtfully specified and commissioned lighting control system," says Michael Jouaneh, marketing manager for Lutron Electronics Co.
A range of lighting control strategies are available to help facility managers be efficient. These include the following:
Astronomical time clock scheduling. This automatically dims or turns lights off at certain times of the day. Few buildings operate on 24-hour schedules, and many are empty during the overnight and weekend hours. These time clocks can be used to provide a building with a "lighting sweep" at night, switching lights off or dimming them at certain times to save energy and prevent light pollution.
According to Jouaneh, astronomical time clocks are preferable to standard time-of-day time clocks because they automatically adjust lighting based on such events as sunrise or sunset. Scheduling can reduce lighting costs by 10 to 35 percent.
Bi-level switching. These systems, which provide two levels of "on" in addition to "off," can provide up to 18 to 20 percent savings. There have been cases where savings are even greater.
Occupancy sensing. These sensors automatically turn off lighting when occupants leave a space. The average savings tally up to about 35 percent, according to Freshman. Occupancy sensors are best suited for private offices, conference rooms, restrooms and classroom spaces.
"Besides traditional uses, occupancy sensors also can be integrated into stairwell luminaires for additional savings," says Dorene Maniccia, director of policy and industry affairs for Watt Stopper. "And they can be used to signal other building management systems."
Care should be used in setting time delays on fluorescent systems, so that no more than six starts per day occur even when using "program start ballasts" or maintenance replacement cost could decrease overall savings.
Digitally addressable dimming ballasts. This technology is fully controllable, and scalable for applications ranging from small, standalone spaces to multiple rooms and areas, to whole floors, entire buildings or even expansive campuses. It allows light fixtures to directly network with time clocks and occupancy sensors, as well as daylight sensors, wall controls, handheld remote lighting controls, window shades and building management systems.
"Digital lighting controls are one of the most recent and robust technologies available today," Maniccia says. "Advanced lighting control systems emerging in the market are smarter, easier to connect than traditional wiring, offer self-commissioning, report on usage and save more energy. These systems take advantage of the benefits of digital control and plug-and-play cabling to provide these benefits."
Tuning. Lighting energy use can be reduced by 20 percent or more through tuning, which sets the appropriate light level for each space. Existing buildings are usually significantly over-illuminated. Light levels are set for the worst-case scenario, which is typically much higher than desired. For this reason, a facility manager can "tune" a new lighting system that is controllable via dimming ballasts to the right light level for each space. For instance, some areas may require 40 foot-candles or light on the work surface while others need only 20. This strategy can save a significant amount of energy while making occupants more comfortable and productive.
"Even when you employ tuning, many occupants prefer lower light levels to minimize glare on computer screens," Jouaneh explains.
Daylight harvesting. This option automatically dims electric lights when enough daylight is present and typically can save an additional 10 to 16 percent in lighting electricity costs in buildings with many windows or skylights.
Personal controls. Personal lighting controls allow users to control general lighting directly over their workstations. Studies suggest that the ability to vary lighting to levels appropriate to the job at hand can improve productivity and reduce eyestrain and glare. This is in addition to saving energy — about 10 percent more than a standard lighting upgrade alone.
Wireless controls. Wireless options save on the costs of installing new line-voltage wiring, as well as reducing the impact on the building occupants. According to Freshman, ROI can be achieved on many projects within one year. Products include occupancy sensors, line-voltage controls, photocells for daylight harvesting and relay control systems for scheduling.
Taking advantage of wireless controls for renovations can reduce cost as much as 50 percent compared to wired systems, Freshman says.
One organization, BC Hydro, a Canadian electric utility in British Columbia, had a chance to realize energy savings when it moved to four floors in a new office building. The company installed a product that integrates network controls, occupancy sensors, personal dimming and daylight dimming.
BC Hydro reported reductions in lighting energy consumption in the range of 77 to 83 percent. What's more, the payback was only 1.5 years instead of the three years predicted prior to installation. Toronto Hydro recently replaced most all HID exterior luminaires with controlled, fluorescent weatherproof luminaires, to save nearly 77 percent in lighting energy costs for parking lots, parking garages, parking decks, security, docks, etc.
Benefits of lighting controls go beyond electricity savings. One such benefit can be a reduction in cooling load.
"Because lights emit heat, lighting controls and upgrades can reduce HVAC demand," Jouaneh says. "As a rule of thumb, for every 3-watt reduction in lighting power, there is a 1-watt reduction in cooling load."
What's more, savings from lighting controls require little, if any, participation from building occupants once they are set to run.
"Lighting control products operate automatically and do not need any action from the building occupants," Freshman says. "This means savings generally are not affected by building use. They happen automatically."
Exterior and Other Lighting
Outdoor lighting, which includes parking garage lighting, is one of the most overlooked areas during a lighting upgrade, experts say. It's a significant missed opportunity, because it can provide energy savings and operating cost reductions.
"Many people don't believe exterior lights are as important to the budget as those on the inside," says Larry Leetzow, president of Magnaray International Division. "But they also forget that outside lighting is on at least 12 hours a day, as long as inside lighting. Exterior lighting makes a building secure. It makes people secure."
A company in the San Francisco Bay area evaluated its outdoor lighting system after an employee was mugged in the facility's brightly lit parking lot, which used low-pressure-sodium lighting. After the mugging, the company hired a security guard to escort employees, many of whom kept non-traditional working hours, to and from their cars.
"It turned out that while the lot and surrounding walkways had bright lighting, the orange color of the lighting created reduced visibility," Leetzow said. "By changing the system to a white fluorescent system, the lot was better illuminated, saved $4,000 each year on energy and maintenance, and cut their security bill by $58,000 because they no longer needed a full-time security guard. High color rendering, good glare control and uniformity of lighting are non-negotiable."
As Bennorth says, lighting issues also come into play in parking garages. Typically these areas are lighted 24/7, but in theory, this isn't always necessary.
"Converting this lighting to a controllable, energy efficient source — such as high-efficiency fluorescent lighting — will save energy when the lights are on and also allow savings when the lighting can be reduced or shut off, based on a schedule, occupancy sensors or available daylight," he says.