Below is my contribution to the June issue of tED Magazine on the topic of LED upgrade options for HID luminaires. Reprinted with permission.
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 National Electrical Manufacturers Association’s (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 percent 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, though careful product selection and application is 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 up to 400W for replacement of 50W up to 1000W HID lamps, with average lamp efficacy around 110 lumens/W. In terms of color quality, 2000K to 5000K correlated color temperatures (CCT) are available offering very warm to very cool shades of white light, and with color rendering 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.
Ballast-driven lamps. These plug-and-play lamps screw into the existing socket and operate on the existing ballast and wiring. No modifications are required to the luminaire, making this option relatively quick and low-cost. Light output varies but ranges from about 2,000 to 20,000 lumens.
However, these lamps utilize the existing ballast, which presents an eventual point of failure an additional 40-60W of load. In some cases, the LED lamp must be properly matched to the type of ballast (metal halide, high-pressure sodium, etc.).
Line-driven lamps. These lamps bypass the existing ballast and operate on line voltage (120-277V), eliminating the ballast and its associated energy and maintenance costs. Some lamps qualify for listing by DLC. Light output varies but ranges from about 1,500 to 15,000 lumens.
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.
Retrofit kits. A retrofit kit modifies the existing luminaire in a way that will no longer accept HID lamps. This satisfies the utility because it eliminates the possibility of “snapback” to less-efficient technology. It also may provide a marginal efficacy improvement over lamp replacement. Many are listed by DLC, qualifying them for certain utility rebate programs.
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 D. Engle, Product Manager, New Product Innovation, Hubbell Lighting. “There is a good offering of wattages, CRI and CCT. Some are DLC-listed. Most carry an industry-acceptable warranty between five and 10 years.”
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.
Light output. The majority of LED HID replacement lamps feature a “corncob” design, approximating the light emission of an HID lamp. Directional PAR lamps are also available. These lamps and LED retrofit kits often feature a flat chip-on-board design.
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 (CBCP), 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.
Lighting quality. LED replacement lamps and retrofit kits should provide similar light distribution as the incumbent lamp while potentially improving color quality.
“If properly designed, the replacement does not compromise light distribution both in terms of center beam punch as well as off-axis consistency,” said Tom Quinn, Vice President of Sales, Lunera Lighting. “It is possible to review a polar plot that compares the light distribution of a fixture using a standard HID lamp versus an LED replacement lamp.”
Socket condition. Evaluate the condition of the luminaire and socket prior to committing to an LED option. “An ideal condition for replacing HID with LED would be a socket that is not aging,” LaSpina said. “Also whether the base is medium or mogul as HID LED replacement lamps tend to be heavier than their traditional counterparts, and the socket needs to take the weight of the new product. If the sockets are older, a replacement would be needed prior to installing the LED solution.”
Temperature. The lamp should be properly designed for the ambient heat conditions. “A properly designed LED lamp should be able to deliver adequate lumens to meet the needs of the application while maintain an LED package temperature that assures the LED chip will operate reliably over the stated 50,000-hour L70 life,” Quinn said. “A good LED replacement lamp manufacturer should be able to provide in situ test data showing the temperature of the LED chips remains below the chip manufacturer’s thermal specification when the lamp reaches a steady state operating temperature when deployed in a typical application.”
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 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.”
UL. The LED replacement lamp should be Listed and approved for use in the given luminaire. “Depending on the replacement solution, an electrician may be required to bypass the existing ballast,” LaSpina said. “This would void the UL Listing of the luminaire, so it is important to choose an LED replacement that has a dual UL Listing—UL 1993 and 1598c—which would carry the listing that is required for retrofit.”
Control. The majority of LED lamps are not controllable. LED retrofit kits are typically packaged with standard drivers that feature 0-10V leads that can be connected to control systems. This makes a wide range of lighting control strategies available to luminaires that had limited options when fitted with HID lamps. These strategies can generate additional energy costs savings, extend life, increase flexibility and potentially produce data.
“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.”