I recently had the pleasure of interviewing Scott Roos, Vice President, Product Design, and Kristin Fedoruk, director, Energy Sales and Solutions, Juno Lighting Group. The topic: LED high-bay lighting. I’m happy to share her responses with you here. The interview informed an article I wrote for the September 2015 issue of tED.
DiLouie: How would you characterize current and future demand for LED high-bay lighting in the new commercial building market? Retrofit market?
Roos: LED high-bays are equally well suited for both new construction and retrofit applications. However, the reality of the current market is that there are simply many more retrofit project opportunities available. One-for-one retrofits are driving most of the market and this will likely continue for the foreseeable future.
Fedoruk: Due to the falling price of higher wattage LED luminaires during the past couple of years, the opportunity is now greater for an end user’s return on investment to increase. It becomes a very attractive proposition – especially when figuring the cost of waiting on a traditional sourced high-bay replacement with a LED high-bay. In addition, LED fixtures can be eligible for rebates from utilities and LED fixtures require virtually zero maintenance for many years.
DiLouie: What market share does LED lighting have against HID and fluorescent in the new construction high-bay lighting market?
Roos: In dollars we estimate that LED high-bay lighting will account for over half the sales in this category in 2015. If we measure in units, however, LED high-bay penetration looks to be around 20 percent, but is growing rapidly at more than 25 percent per year. At that rate it won’t be long before LED captures dominant share both in terms of unit and dollar sales.
DiLouie: What advantages does the LED source offer compared to fluorescent and HID for these luminaire types?
Roos: In comparison to metal halide, LED has five times longer life, much higher lumen maintenance and instant start capability, which of course comes into play when using them with controls. 0-10V dimming has become a standard, and on/off or high/low sensors are a popular option. Based on mean lumens, fixture efficacies can be more than double when comparing to older probe start technology or 40 percent higher when comparing to the most efficient generation of electronically ballasted Pulse Start metal halide lamps. These savings can be substantially higher if lighting controls such as occupancy sensors and daylight harvesting are used, which were not practical to apply with most HID systems.
Compared to linear fluorescent, LED high-bays can have up to two-and-a-half times longer life – although to be fair – there are now longer life linear fluorescent lamp options that compare favorably with LED L70 lifetimes. LED luminaire efficacies of over 100 lumens per watt can be 30 percent higher than the typical fluorescent high bay, which translates directly into energy savings. The potential of LED technology to maximize energy savings and return on investment can be best realized on new construction projects that are not locked into fixture spacing based on older technologies. This is because LED high-bays with advanced optical design can more precisely and uniformly distribute fixture lumens, allowing the use of fewer luminaires spaced further apart.
DiLouie: How would you characterize current LED high-bay luminaire offerings in terms of light output, sizes, optics, wattages, CRI, color temperatures, service life, and compatibility with or integration of lighting controls?
Roos: On all of these criteria LED high-bay luminaires have the ability to perform extremely well. How well depends on how a manufacturer thermally and optically designs the luminaire and selects/bins/operates the LEDs. Like any other category of products, when trying to meet the lowest market price levels, some of the performance will be compromised. For example, driving the LEDs especially hard in attempt to reduce the LED count will lower fixture efficacy and shorten the L70 life. And LED high-bays are generally very easy and economical to integrate with lighting control systems; often the standard driver has dimming capability.
DiLouie: What are typical energy savings for a design with HID or fluorescent versus LED high-bay lighting, assuming an equivalent maintained light level?
Roos: The savings are greatest in comparison to outdated Probe Start Metal Halide systems, where a two to three times energy savings can be expected, especially in an application that the fixtures are on 24 hours a day, seven days a week. Compared to more efficient Pulse Start Metal Halide lamps, energy savings in the range of 30 to 40 percent are typical. On top of that additional savings can be achieved with the use of controls such as occupancy sensors or daylight harvesting that are generally not practical with HID lamps. As compared to linear fluorescent high bays, a 30 percent energy savings would be typical when converting to a well-performing LED high-bay.
DiLouie: What are the top trends in LED high-bay luminaire design? Please note the differences in how these LED luminaires are designed differently from their HID and fluorescent competitors.
Roos: There are three general types of LED high-bay luminaire designs:
The most efficient are ones that place discrete TIR optics over each LED in a large array to very precisely and efficiently distribute the light. This type of fixture makes the best use of the available lumens and substantially fewer lumens can achieve similar levels of light when compared to traditional technologies. These fixtures are generally higher in cost due to the number of LEDs, optics and wiring harnesses involved in the design. They can also be difficult to justify on one-for-one retrofit projects, as fixed luminaire spacing based on the limitations of legacy technologies do not take full advantage of their extraordinary optical performance.
Next are rectangular fixtures that mimic the general design of linear fluorescent high-bays. These fixtures typically use linear arrays of lower power LEDs that operate at efficacies of 30 percent or higher when compared to linear fluorescent lamps, which is why they outperform them, even though there is nothing exotic about the optical control.
Finally, there are round form factor LED high-bays that are modeled after the classic HID large reflector or refractor designs. Often these fixtures use single or multiple high-wattage chip on board arrays, sometimes in combination with a glass secondary optic. This type of fixture can be expected to outperform its metal halide counterpart primarily because of the high efficacy of the current generation of chip on board arrays that are used, which can now exceed 150 lumens per watt. Another advantage of this form factor is the round design is most resistant to physical damage when fitted with a wire guard, which is why they are often preferred in applications like gymnasiums where they are more vulnerable. In addition, some commercial and retail applications want to preserve an industrial factory aesthetic with either a plain or decorative round high-bay form factor.
DiLouie: What are the top trends in high-bay lighting in general, and how is this affecting high-bay luminaire design?
Fedoruk: Customers followed electrical distributors’ recommendations for the past 15 years on energy savings. They’ve switched from probe start metal halide to pulse start metal halide or linear fluorescent high-bays. Next, the linear fluorescent customers looked at linear LED (either LED lamp replacements or full fixture). There are still a lot of round high-bay traditional metal halide fixtures out there (either probe or pulse start) and those customers never bought in to the look of linear fixtures. Whether it’s due to the distribution or just physical aesthetics – the need for the round LED high-bay is still there.
DiLouie: What are the main attributes of an LED high-bay luminaire that electrical distributors would be looking at when considering an LED over an HID or fluorescent product?
Fedoruk: If the electrical distributors have the opportunity to offer their customer one or the other, there are many considerations – especially what is important to the end user. Is it service life? Efficiency? Lumen output? Color? CRI? Most LED fixtures have a much better CRI than the traditional probe metal halide. Finally, in industrial environments, the need for lenses in case of a non-passive HID lamp failure (or explosion) is an insurance necessity, while with LED there is no lamp that can fail non-passively. Lenses may alter the output of the luminaire as much as 10 percent.
DiLouie: What are disadvantages or potential pitfalls in selecting or using high-bay LED products that distributors should be aware of, and how they should they mitigate them?
Roos: Higher ambient environments can be a challenge, especially on driver temperatures. Of course, higher ambient environments have always been a challenge even with conventional technology fixtures with electronic ballasts. Distributors should make sure to know the ambient temperatures for the application and select a product that has been designed for that type of environment. Also, chemical contamination is a concern with LEDs. For example, in a manufacturing environment where chemicals are being used, it is best to work with the end-user to identify the specific substances, and then ask the luminaire manufacturer to validate whether or not those particular chemicals will interact with the LEDs.
DiLouie: How do the control capabilities of LED high-bay lighting compare to HID and fluorescent, and what benefits can be achieved?
Roos: LEDs are much easier to dim than either HID or linear fluorescents, and often times the standard driver supplied with the fixture is dimmable at no additional cost. The life of the LED is not affected, even with frequent on-off cycles.
Fedoruk: In many institutional facilities there are multi-use areas (for example, gymnasiums) that in the past were always equipped with metal halide fixtures with wire guards. Now attractive instant-on dimmable luminaire (still with wire guard if needed) are available, and they can be controlled instantaneously for a play, recital, concert or basketball game.
DiLouie: In retail high-bay, issues such as color and sparkle come to the forefront. How competitive is LED compared to ceramic metal halide and similar sources in these applications? What does LED bring to the table that’s unique?
Roos: We have seen most of our retail high-bay lighting customers switch to LED. The advantages of energy savings, longer life and controls integration have trumped any concerns about “sparkle” and color. Frankly, the color rendering of today’s generation of LEDs is superior to what we were able to achieve as compared to either fluorescent or ceramic metal halide. While perhaps not quite as much of a sparkle generator as the arc tube of a CMH lamp, a very high lumen chip on board array in a glass lens still has specular qualities that can generate highlights. We occasionally see retailer preference for CMH trac fixtures for accent lighting because of higher sparkle as compared to LED, but even these instances are becoming fewer as the light emitting surface (LES) of the popular COB arrays gets even smaller.
DiLouie: What impact is the proliferation of LED products having on electrical distribution business practices in general?
Roos: Electrical distributors are stocking fewer SKU’s both because of the larger variety of fixture options and frequent generational performance upgrades that, if they are not diligent, can leave them with obsolete inventory.
DiLouie: If you could tell the entire electrical industry just one thing about LED high-bay lighting, what would it be?
Roos: LED technology is already delivering superior results and the technology will continue to improve and become more affordable. It is highly unlikely that we will go backwards, so it is wise to get on board and learn the new technology.
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