By Kevin Youngquist
Not long ago, warehouses, manufacturing plants, retail operations and even gymnasiums had few options when it came to specifying lighting for their high-bay fixtures. The choice was to either install HID or fluorescent. That’s no longer the case as LEDs now provide more lumens per watt to reach an economic value that makes them an attractive alternative.
With LED system efficiencies exceeding 130 lumens per watt, LED is 3.5 times more efficient than HID and 2.5 times more efficient than fluorescent T8 or T5 fixtures, which results in a rapid return on investment. Since an LED only uses 25% to 30% of the energy of the fixtures being replaced in retrofit situations, an opportunity exists to add more fixtures to the installed lighting system to enhance visibility without incurring additional energy costs when switching light sources.
Longer performance life. LED lamps also last longer, which means they don’t need to be replaced as often. With high-bay fixtures inconveniently located far out of the way making maintenance time-consuming, a longer service life additionally means lower maintenance costs. Today’s high-bay LEDs will typically perform for more than 50,000 hours.
In the past, LEDs were somewhat limited in their applications due to concerns with heat and its effects on service life. However, technology enhancements have improved LED cooling systems so they can now function effectively in an array of temperatures. Rectangular or linear high-bay fixtures can now easily mount the LED chip securely to the frame for cooling over a relatively large surface area. Matching up a high-quality LED with a proper driver has the potential to deliver years of service with excellent lumen maintenance.
Round or UFO high bays can also be configured to dissipate heat from the LED, maintaining a sufficiently low chip junction temperature to ensure a long service life. A word of caution, however, is that not all high-bay, heat transfer systems function the same way, so it’s important to inquire about fixture data to ensure selection of a long-lasting option.
Better color consistency. But efficiency isn’t the only variable, especially when considering lighting in areas where visual clarity is critical. LED provides a better light source with color temperatures of 4,000K or 5,000K and a color rendering index that exceeds 80 available. A major differentiator is that LED provides negligible color shift over time. So if you start with 4,000K, you will end with very close to 4,000K. And, the quality of light will be much better at 80+ CRI.
In comparison, HID, which is also typically available in 4,000K, is susceptible to color shifting. That’s the result of lumen depreciation, which causes light output to decrease quickly after initial installation. Although it is still operational, it provides less-than-optimal lighting for much of its service life.
Fluorescent high-bay fixtures, as another alternative, are often fitted with T8 daylight lamps. Typically available in 6,500K, they provide a very blue-white light source that has been shown to be extremely harsh on workers’ eyes. In situations where fluorescent fixtures are being changed out, 5,000K LED fixtures should be considered. Although they are more white-blue than 4,000K, they provide a softer light that’s more tolerable to work under for hours at a time.
More control and flexibility. Despite previous limitations of LEDs not being able to emit light in all directions, today’s LED fixtures offer maximum flexibility with regard to how light is directed, controlled and designed, offering more lumen levels and light patterns than traditional high-bay fixtures. Newer LED fixtures can be directional to either serve as an “aisle lighter” or provide a fuller, broad angle light source, depending on your needs and the way contractors install them.
It’s important to note, too, that quality LED high-bay fixtures can work with existing building control systems. Most linear high-bay LEDs come standard with 0-10V dimming, which is important if these fixtures are being linked to a daylight harvesting system. There are also UFO high-bay fixtures which, in addition to coming standard with 0-10V dimming drivers, are also IP65 rated for wet locations with protection also from dust, oil and other noncorrosive materials. These models require control sensors to be mounted remotely.
In addition, thanks to technological advancements, LED fixtures can also be linked with an array of sensors, including simple motion sensors. These can be easily mounted to linear LED high bay fixtures to provide tremendous energy savings. Sensors with bi-level control can be easily set to a preferred light level that meets local codes.
Linear LED high-bay fixtures can also be fitted with emergency back-up power packs that supply sufficient light over the recommended time period to meet NFPA and local codes, providing a means of ensuring egress lighting systems are up to code when retrofitting an existing warehouse or manufacturing facility.
Over time, LED has become the preferred lighting source for many applications. Now, thanks to advances in technology, it has evolved to become the smart choice for high bay fixtures, as well. In side-by-side comparisons of energy efficiency, light output and service life, it is difficult to identify a smarter lighting option than LED.
About the Author
As executive vice president of North American operations for Earthtronics, Muskegon, MI, Kevin Youngquist is responsible for the company’s sales, marketing and business operations. He has more than 25 years of lighting experience, including the development of lighting specifications and energy audits for hotels, long-term care and commercial buildings. You can reach him at [email protected]