I recently had the pleasure of interviewing Chris Bailey, LC, LEED AP BD+C, DDI, MIES, Director, Lighting Solutions Center, Hubbell Lighting, for an article I’m writing for TED Magazine about how solid-state lighting is impacting luminaire design. I’m happy to share it with you here.
DiLouie: How would you characterize demand for LED luminaires in indoor commercial building applications in the new construction market? What is current market share in the new commercial building construction market for indoor LED luminaires?
Bailey: The demand for LED luminaires for commercial building applications is very high in general. While our company does not disclose analytics for individual market segments (new construction vs. relight/retrofit), Hubbell Lighting’s overall adoption of LED luminaires is quickly approaching 50%. While this tremendous shift is somewhat influenced by the moderate recovery in the new construction market, in general the installed base of legacy technology in the market will remain the most significant market opportunity in the near future.
DiLouie: What are the most popular applications for LED luminaires in indoor applications?
Bailey: With typical energy savings of 30-40% in most applications, LEDs are quickly becoming the light source of choice for most interior applications. However, interior recessed lighting is a clear winner, followed by industrial and linear ambient luminaires. Going forward, as more contemporary energy codes are implemented around the country, the emphasis towards integrated lighting control solutions is increased. This results in a greater level of LED adoption stemming from the significant costs associated with legacy dimming ballasts. Whereas in many cases adding a dimming ballast can nearly double the selling price of a compact or linear fluorescent luminaire, most LED luminaires come standard with 0-10V dimming drivers. Some of which are capable of dimming below 1%. Another aspect at play is that for recessed down lighting applications, delivering greater than 6500-7000 lumens from a reasonable sized aperture can be challenging. This necessitated the use of medium to high wattage HID or high wattage halogen lamp sources in higher mounting height applications. Considering the maintenance and energy savings available for either scenario, the recessed lighting market has been quick to leverage LED technology.
The linear market is quickly moving this direction as well, however the inherent source efficacy (100-110lm/W), lumen maintenance (~90%+), relatively high luminaire efficiencies and low cost have slowed the adoption, compared to the downlight market. Given the same forces at play with respect to energy codes and the cost of dimming ballasts, the tipping point is nearing.
Speaking briefly on industrial applications, the market adoption falls in-between that of downlighting and recessed linear applications, towards the upper end. Over the past 10-15 years, industrial spaces have largely shifted to linear fluorescent technology. While HID industrial luminaires are regarded as easy targets, those systems which have been converted to the latest generation of linear fluorescent technology may be delayed in their conversion to LED.
In the spirit of completeness it is worth mentioning that while considerable increases in legacy source efficacy are not anticipated, legacy source manufacturers continue to deploy rolling improvements in lamp life (50% mortality). Commercially available CFL, HID and linear fluorescent lamps are now available with rated lifetimes of 30,000, 40,000 and 90,000 hours, respectively. Therefore applications considered to be prime targets for LED, specifically those using linear fluorescent lamps, may rely more on energy savings than maintenance avoidance.
DiLouie: What are the top 3-5 trends in indoor LED luminaire design today?
Bailey: There are several trends playing out today. In the interior commercial space, many of these trends are centered on color. Interestingly, despite its 100+ year history and relative inefficiency, incandescent (and halogen) lamps are still the established baseline for color quality. This is in part due to the smooth and continuous nature of its spectral power distribution and the overall completeness of the spectrum – which spans the entire visible spectrum. Irrespective of its misgivings, legacy and LED manufactures alike strive to capture the inherent color quality of this century-old source. Something else perhaps taken for granted the ability for incandescent sources to be dimmed easily and maintain color quality, yet decrease in color temperature (black body dimming) through the dimming range. As a result, many companies have begun to design and offer commercial interior luminaires designed to emulate the signature color quality and dim-to-warm characteristic of incandescent and halogen sources.
With respect to color quality, a few variations have emerged – with the same goal in mind. The first of these variations involves special phosphor blends (remote or local), which improve the overall spectral content, with specific emphasis on the deep red part of the spectrum. Another interesting development involves the utilization of a violet LED in lieu of a blue LED for phosphor stimulation (photoluminescence). The result of which more fully completes the spectral content of the LED source, which improves perceived color quality and more naturally renders the colors and shades of white. Lastly, some companies have begun to break tradition intentionally move the color point of warm white products off of the black body locus and away from the center of the ANSI quadrangle, in an effort to provide a more balanced spectrum.
In the same vein, the demand for tunable white products is on the rise. Companies are now introducing luminaires, for which the color temperature can be decided and set electronically, after installation. This provides a welcomed level of flexibility to otherwise static products. This technology is also available in configurations that allow end-users to supplement colors in the spectrum by changing the hue and saturation, separately from CCT. It should be noted however, that in addition to the added acquisition cost, products providing this level of flexibility require greater amounts of energy to operate – which may limit their initial acceptance.
Deep dimming (1% and below) and the reduction of perceivable flicker are also areas of interest today. Many power supply manufacturers now offer variations of their otherwise standard products, which greatly improve electrical and dimming performance in these areas.
Lastly, AC-LED technology continues to improve and move from purely residential products into those that serve the light commercial marketplace. AC LED products do not require a traditional power supply and instead utilize PCB-level components, which regulate the current delivered to the LEDs. Future developments in the area of voltage compatibility and flicker reduction will make the transition into commercial products possible.
DiLouie: What impact are these trends having on the market in terms of moving the ball forward, satisfying users, and exceeding current conventional lighting offerings?
Bailey: Necessity is the mother of invention. All of the trends mentioned above offer significant improvements in the areas of immediate concern or interest. As additional concerns or needs are raised, innovations will follow. The improvements listed above also satisfy broader requirements needed to facilitate mass adoption. In parallel to these rolling improvements, critical supply channels continue to broaden and mature, ultimately resulting in lower costs and a greater degree of adoption.
DiLouie: Where do you see these trends going in terms of future direction?
Bailey: Improvements in cost, quality and performance are expected to be realized at an ever-quickening pace. However, it is important to note that some degree of stratification has occurred in the lighting marketplace. This is consistent with the conventional lighting market place, where products can be categorized as commodity, specification or somewhere in between. In other words, LEDs are now equally relevant for most any application – not just the specification market.
DiLouie: What do you see as future trends in indoor LED luminaire design that will become possible as the technology continues to develop?
Bailey: Tunable white products may become more available and affordable going forward. This level of flexibility is likely to start as very niche, but continue to be deployed in lower cost products going forward. Additionally, the direct integration of wireless technology such as Bluetooth (BLE) may become more practical and will be used to support added functionality. The desire, and perhaps need, to render a greater degree of control over luminaires individually or as groups and systems, may lead to the direct incorporation of relativity low-cost wireless technology, such as BLE, and the related development of app-based control solutions for commercial applications.
DiLouie: Please comment on the evolution of optics for indoor LED luminaires, giving particular focus on how optics have changed to accommodate the LED light source.
Bailey: Given the inherently directional nature of LED sources, optical systems optimized to take advantage of these characteristics have emerged. The most common of these are TIR optics, which are typically made from injection-molded acrylic and make optical efficiencies of greater than 90% possible. Not only are TIR optical systems efficient at transmitting light into the space, they uniquely enable the precise placement of light within a space. This is not to say that reflector-based optics are no longer relevant, in fact many luminaires deploy a combination of optical technologies in an effort to better focus visible energy and provide visual comfort. However, TIR optics are generally more efficient and often require less reflections and bounces to achieve a desired distribution.
Additional developments have been made in the area of edge lighting, light guides and micro or imprinted optics, where complicated optical structures are created on thin optical sheets or films which are capable of both diffusion, trasmission and photometric control.
DiLouie: What are your thoughts on the evolution of integration of lighting controls within indoor LED luminaires?
Bailey: The integration of wireless controls is currently underway. The integration of daylighting and occupancy/vacancy sensing is currently an option on many luminaires, regardless of source. As we move towards more aggressive energy codes, the integration of sensors and controls in luminaires will become a necessity. As such, many manufactures of such controls have made great efforts recently to reimagine and develop fixture level sensors which are more commiserate with the form of interior luminaires and far smaller than those previously available.
DiLouie: What is your perspective on the evolution and viability of indoor LED luminaires with mechanisms that indicate end of life or otherwise maintain a constant light output over life?
Bailey: Products, which provide constant light output or end of life notification, are now commercially available from many luminaire manufactures. More often, this functionality is enabled by programmable LED drivers, which can be configured with customizable timed-based curves, which initially operate the LEDs at lower drive currents and slowly increase drive current to offset the anticipated lumen depreciation. As an added benefit, extended luminaire lifetimes are often achieved as a result of operating LEDs at a lower average current through the life of a luminaire. It is important to note, however, that the associated curve may be best determined by understanding the anticipated operating environment of the luminaire (hours of use, operating ambient temperature, etc.). This may lead to a greater level of energy savings, or greater time-based adaption, than would otherwise be possible through generalization.
DiLouie: Please comment on the evolution and demand for indoor LED luminaires that feature serviceable components such as light engines, drivers, heat sinks and optics?
Bailey: There are two schools of thought. On one hand, having serviceable components provides some customers with peace of mind. However, the likelihood that a compatible PCB, which emulates the photometric and color characteristics of an older generation product is likely not to be available 3-5 years after installation. Compatible drivers may be available, however the industry has only “loosely” standardized on the physical size and mounting features. Those luminaire manufacturers participating with the Zhaga Consortium would be the exception and may be able to provide some degree of future compatibility. As a result, I would emphasize the quality of components and the expected life over the ability to be replaced. If serviceable components are desired, I would recommend keeping specialized components on-hand as attic stock.
DiLouie: How are form factors for indoor LED luminaires evolving, and what is the viability of new form factors?
Bailey: Whereas legacy luminaires where built around obtuse lamp sources, LED luminaires have the unique ability to transcend traditional luminaire design and break new ground. LEDs can be incorporated directly into the fabric of a luminaire concept. Flexible and translucent circuit board technologies provide the ability move luminaire designs from routine, predictable and rigid forms and into an era of freeform design without rules of scale, size and structure.
DiLouie: What is your perspective on the evolution and viability of indoor LED luminaires with specifiable, factory-customized light output and wattage to satisfy precise application needs?
Bailey: Historically, legacy sources could be adapted in terms of power consumption and light output though the modification of ballast factors. This function was driven from the need for one luminaire with a fixed number of lamps to accommodate a variety of applications and power density requirements. This need has not retreated with the emergence of LED luminaires. In fact, despite the increases in LED luminaire efficacy, energy codes precipitously reduce power density allowances. As such, “tunable” products are likely to be highly appreciated by consulting engineers who continue to design for these ever evolving and requirements.
DiLouie: If you could tell the entire electrical industry just one thing about trends in indoor LED luminaire design for commercial building applications, what would it be?
Bailey: Future lighting products are likely to test the boundaries of form and function, provide nearly unlimited flexibility to address color, photometry and human health will be capable of field or factory configurations tailored to end-user preference and onsite conditions and yes, there will be an app for that.