By Craig DiLouie
As a popular light source for industrial, retail, public space, parking garage, and outdoor area and roadway applications, high-intensity discharge (HID) lamps represent an enormous installed lighting base.
LED technology has progressed to offer energy-saving, long-life alternatives for virtually every application, including those traditionally served by HID luminaires. The impact on HID lamp demand is suggested through the lens of the NEMA HID Lamp Index, which has shown a steady decline.
In recent years, manufacturers have begun developing retrofit options targeting existing HID luminaires. LED replacement lamps enable a potentially lower-cost option for switching to LED, with up to 50% energy cost savings. Other advantages include instant-on operation, improved lumen maintenance, universal operating position, good color quality, and long life. LED retrofit kits package the lamp with other components for a repeatable solution that effectively becomes a new luminaire.
The strong potential of these products has led to recognition within the DesignLights Consortium’s (DLC) Qualified Products List used by many utility rebate programs to qualify products. The number of utilities offering rebates promoting these lamps jumped from 10 in 2016 to nearly 120 in 2017, according to BriteSwitch, with an average rebate of $110 per lamp.
As a result, LED replacement lamps and retrofit kits offer viable upgrade options, although careful product selection and application are necessary to yield desired results.
Lamp upgrade options for existing HID luminaires include ballast- and line-driven LED replacement lamps.
Overall, wattages range from 30W to 400W for replacement of 50W to 1,000W HID lamps, with average lamp efficacy around 110lm/W. In terms of color quality, 2000K to 5000K correlated color temperatures (CCTs) are available offering very warm to very cool shades of white light, and with colorrendering index ratings typically in the low 80s. The majority of products offer service life of 50,000 hours at L70 lumen maintenance. And most carry a warranty between five and 10 years.
A very common upgrade is 150W and 200W LED lamps rated at 17,000 to 21,000 lumens replacing 400W metal halide lamps.
However, these lamps utilize the existing ballast, which presents an eventual point of failure of an additional 40W to 60W of load. In some cases, the LED lamp must be properly matched to the type of ballast (metal halide, high-pressure sodium, etc.).
However, this option is typically more expensive in terms of labor than ballast-driven lamps, as a qualified electrician must perform the necessary electrical modifications to bring line voltage to the sockets.
Often, installing a retrofit kit requires replacing the ballast with an LED driver. Secondary optics may be packaged with the kit.
“Both LED replacement lamps and LED retrofit kits are a quickly growing area right now,” said Joseph Engle, product manager, new product innovation, Hubbell Lighting (hubbelllighting.com). “There is a good offering of wattages, CRIs, and CCTs. Some are DLC listed. Most carry an industry-acceptable warranty between five and 10 years.”
The Right Application
When applying LED replacement lamps and retrofit kits to HID luminaires, many factors must be considered, including light output, lighting quality, socket condition, temperature and other environmental conditions, UL listing, and controls.
Be sure to make lumen comparisons based on application light level needs, lumen depreciation rates, and luminaire optical efficiency. If the lamp is directional, be sure to consider center beam candlepower, which is the light intensity directly in front of the lamp. And always remember a rule of thumb for effective lighting upgrades is to save energy while maintaining or improving lighting quality. “Make sure to maintain the overall light quality and output that the customer is used to,” said Alfred LaSpina, LED product group marketing manager, LEDVANCE (sylvania.com).
That being said, Engle warned that LED lamps may not be able to withstand the high ambient temperatures present in some HID lighting applications. “Be careful about the environment that these lamps and kits are used in,” he said. “The HID fixture was carefully designed to do a specific lighting job and survive a specific environmental condition. Always make sure that the LED lamp or retrofit kit does not compromise the lighting job and will work in the environment.”
Another aspect of temperature is that LED lamps produce a fraction of the heat of HID lamps, which can be beneficial in conditioned spaces. “If the installation has people utilizing the space, cooling methods may be necessary to maintain a comfortable environment, which adds to a building’s energy costs,” LaSpina said. “This isn’t an issue with LEDs.”
“Building owners have three choices for upgrading lighting infrastructure,” said Quinn. “One, do nothing. Two, do something. Three, do everything. Doing nothing is shortsighted as there are valuable operational savings that can come from an LED lighting upgrade. Doing everything is still expensive. Doing something is the obvious play. Converting an existing building to LED via a lamp upgrade or retrofit conversion is simple, safe, and affordable. Expect payback to be inside of one year when converting from HID to LED.”
“The best advantages of LED replacement lamps and kits are the easy installation and the low cost,” Engle said. “The disadvantages are questionable reliability, questionable thermal performance, and mismatch to the application. The best application for both of these products is a damp or dry location that will not see extreme temperatures or high dirt conditions. In these applications, the reliability and thermal performance issues are minimized.”
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