Energy-efficient light sources are only one part of the process of reducing the energy used by a lighting system. A well-designed control system will provide the right amount of light where and when it’s needed, and it will cut lighting energy use by 5 to 60 percent depending on the baseline conditions and the control strategies used. Advanced control systems can improve maintenance by signaling lamp outages and monitoring usage and output levels to indicate when they fall below required levels.
A variety of strategies are available to cut lighting energy use. Lawrence Berkeley National Laboratory (LBNL) recently reviewed 240 savings cases and summarized the average savings achieved from all major control types:
Even more savings with LEDs
Most of the studies reported on by LBNL looked at fluorescent lighting. But LEDs offer the potential for even more savings for several reasons.
• Instant response and no cycling effect. LEDs respond instantly, and their lamp life is not shortened by frequent switching. Fluorescent lamp life decreases the more frequently the lamps are cycled on and off; high-intensity discharge (HID) lamps have a long delay time on start-up and re-strike.
• Dimmable. LEDs can be dimmable, but care must be taken to ensure that they’re compatible with the dimming controls in use. For some products, dimming can lengthen the life of LEDs because they run cooler when dimmed, which will reduce the rate of lumen degradation and also lengthen the life of electronic components. Researchers have yet to quantify the effect, but the increase in lamp life will depend on the LED product and its thermal management, the driver and dimming circuitry, and how often and how deeply the lamp is dimmed.
• Color controllability. Good LEDs can maintain a constant color temperature as they dim. Controls can also be used to change the color temperature of LED lighting, a feature used in a growing number of products to mimic the dimming behavior of incandescent lamps. Color-changing can also be used to support applications that are evolving out of a growing body of evidence that color temperature can play an important role in improving human health and productivity.
When LEDs and controls are combined in an installation, the savings can be dramatic. A Sacramento Municipal Utility District (SMUD) program found lighting energy savings of 50 to 90 percent in more than a dozen projects. About 60 percent of savings were from the light-source upgrade and 40 percent from the addition of controls.
Big savings potential with controls
One of the challenges in justifying LED controls is that LEDs generally use less energy than conventional light sources do, so there is a smaller amount of energy to be saved through controls. However, the improved controllability makes it possible to save a larger percentage of that energy. In practice, cost-effectiveness will vary with the application, with the best cases being those with long of hours of operation, irregular operating times or inconsistent occupancy:
• Rapid payback. The SMUD program on advanced lighting controls found rapid payback in industrial applications where:
—High-bay fixtures operate for long hours
—Few controls are already in place
—Big savings are available per fixture
—There are often large areas with low occupancy levels
• Longer payback. SMUD found good percentage savings in office buildings, but the payback was longer because:
—The facilities already typically used some type of automatic control
—They operated for fewer hours
—Each fixture represented a smaller load
Variations in cost. An analysis presented at the U.S. Department of Energy’s 2013 Solid State Lighting Market Introduction Workshop found that advanced controls can add $0.50 to $2.27 per square foot to the cost of a lighting project in a laboratory or office facility.
Non-energy benefits. Cost-effectiveness estimates often don’t account for the non-energy benefits of controls—things such as lower maintenance costs, a better experience for occupants, and the ability to monitor and analyze the use of select spaces within a building. Accounting for those factors can add to the overall estimate of a project’s value and shouldn’t be ruled out.
The market is growing
The market for lighting controls is growing thanks to falling prices for controls, growth in the use of LED lighting and controls requirements found in the latest energy codes. For example, a 2015 report from Navigant Research, “Intelligent Lighting Controls for Commercial Buildings,” predicts that revenue from global networked lighting controls will grow from $2.2 billion in 2015 to $4.8 billion in 2024. Also influencing that growth is an increasing awareness of non-energy benefits such as lower maintenance costs, improved occupant experience, and the ability to monitor and analyze the use of various spaces within a building.
For more information
For more information about how you can improve energy efficiency in your business, visit Xcel Energy’s website at xcelenergy.com/Business.
(c) E Source
Reprinted with permission.