IES Publishes Research on LED LDD

LED area and roadway lighting promises energy and maintenance cost savings, but the longevity of the LED light source presents a hitch. Traditionally, luminaires are cleaned upon relamping. If relamping does not occur, dirt buildup becomes a more important maintenance factor. That being said, it is claimed LED luminaires are less prone to dirt accumulation. So what’s an appropriate cleaning interval?

In 2016, the Illuminating Engineering Society published an important maintenance study conducted by the Virginia Tech Transportation Institute as IES-RES-1-16. Specifically, VTTI looked at luminaire dirt depreciation (LDD) in LED roadway luminaires, impact on light distribution and the efficacy of different cleaning methods.

The study evaluated the impact on dirt and various cleaning methods on a range of luminaire types in both in a laboratory and in the field. While insufficient sampling did not yield new LDD curves, the authors were able to recommend a linear LDD rate for consideration. Key findings:

* LDD is different for LED luminaires and can be significant at end of life
* An alcohol solution or mild detergent solution can be safely applied to many luminaires and is more effective at mitigating LDD during cleaning than dry wipe or plain water
* Minimum potential LDD and change in lighting uniformity rates are +1 percent per year LDD and +1 percent per year uniformity change for luminaires with flat glass luminaire optics, and +3 percent per year LDD and no uniformity change for luminaires with no luminaire optics.

These findings and plenty more can be found in the study, which is available free for download here.

DOE Publishes Report on LED Street Lighting’s Impact on Sky Glow

DOE has published the results of a study of the expected contributions to sky glow from converting high-pressure sodium (HPS) street lighting to broader-spectrum (i.e., white light) sources, with specific focus on LEDs, and presents the contributions in a manner relative to HPS baseline conditions. These conditions represent typical conversions in the U.S. and include changes in spectral power distribution (SPD), percent uplight, and lumen output.

Among the findings of An Investigation of LED Street Lighting’s Impact on Sky Glow:

• All of the LED product conversions reduce sky glow relative to an HPS baseline when the results are expressed as unweighted radiant power, for both near and distant observers.
• When the results are scotopically weighted to evaluate the effects on human vision, some LED products reduce sky glow for the near observer compared to the baseline, and others increase it, depending on their relative content of shorter wavelengths. An important related finding, however, is that CCT is not a very reliable predictor of sky glow impacts, especially when scotopic weighting is not applied.
• Overall, the results for LED conversions in this study ranged from a low of 0.2 to a high of 1.6 times the baseline HPS sky glow, depending on the combination of variables and factors studied.
• For a distant observer under the scenarios modeled, even at only 40 kilometers from the city center, the elimination of uplight that occurs in typical conversions nearly removed (by 95% or more) the contribution to sky glow from the street lighting system, for both the unweighted and scotopically weighted results, for all SPDs and atmospheric conditions.

Click here to get the report.

Jim Brodrick on the DOE’s 14th Annual SSL R&D Workshop

Republication of Postings from the U.S. Department of Energy (DOE) Solid-State Lighting Program by Jim Brodrick, SSL Program Manager, U.S. Department of Energy

Although I recently spent a week at the beach, there was no sand, surf, or bathing suit in sight. That’s because I was in Long Beach, CA, at DOE’s 14th annual Solid-State Lighting R&D Workshop. And instead of hanging 10 on a breaking wave, I rolled up my sleeves along with the other 250 folks in attendance, as we dove headfirst into the toughest technological issues facing SSL today.

The speakers were truly amazing, and kept the audience riveted to their seats right up until the very end of the third day. The father of LED lighting, Shuji Nakamura, who won the 2014 Nobel Prize in physics for inventing the energy-efficient blue LED, set the tone by focusing on SSL’s cutting edge, wowing the crowd with his discussion of such innovations as tunnel-junction blue/green LEDs, violet LEDs, microLEDs, patterned sapphire substrates, high-power semipolar laser diodes (LDs), and Li-fi using LEDs and LDs.

One recurrent theme in Long Beach was that, thanks to the advent of SSL, lighting is no longer “just lighting” and offers many new possibilities. Bruce Bugbee of Utah State University discussed the science as well as the practical economics of using LED lighting in indoor farms to turn photons into food, explaining that selectively tuning the spectrum can not only increase crop yield, but can also change such characteristics as nutritional content, disease resistance, appearance, and taste.

In a panel discussion on creating value from human physiological responses to light, Windy Boyd of the National Institute of Environmental Health Sciences explained that by affecting our circadian rhythm, exposure to light at night may have the potential to increase our risk of common diseases. Jamie Zeitzer of Stanford University reviewed key studies on how light affects the sleep-wake cycle as well as alertness; while Michael Herf discussed f.lux, a software program he created that’s used by more than 10 million people to adjust the CCT of their computer screens in support of their circadian rhythms and biology, and how he’s worked to model the effects on sleep and health of the screens and light people are exposed to. NASA flight surgeon Smith Johnston III discussed the role of lighting in his treatment of the astronauts under his care.

Another panel explored the use of engineered light to accommodate various applications. Wouter Soer of Lumileds concluded that we need more application-based metrics for spectral design, while Konica Minolta’s Po-Chieh Hung cautioned that although spectral optimization is possible for virtually any application, the “spiky” spectra that result may distort color perception both visually and photographically. Scott Rosenfeld of the Smithsonian American Art Museum looked at minimizing light-caused damage to art objects, while Rensselaer Polytechnic Institute botanist Tessa Pocock considered the action spectrum from a plant’s point of view. In a separate talk, Susanne Seitinger of Philips Lighting described how connected lighting can play a key role in creating smart cities by leveraging the existing infrastructure to provide valuable information on the environment, traffic, noise, and the network itself.

A panel on the future of SSL manufacturing in the U.S. — which featured representatives from Cree, Acuity Brands, Hubbell Lighting, and Finelite — emphasized the opportunity that exists to add jobs domestically, as well as the gains that have already been made. The panelists cited cutting-edge R&D, a high degree of product complexity, offering large numbers of SKUs, right-sizing production facilities, and instituting lean manufacturing practices as among the keys to helping the country maintain its leadership in the technology.

There were many other topics covered at the Long Beach workshop — from the challenges facing the luminaire industry, to the synergy between lighting and display technology, to the integration of lighting into buildings, to an Asian LED manufacturer’s perspective on the lighting market. And the LED and OLED breakout sessions and topic tables literally crackled with energy as they came to grips with the remaining technological hurdles (see DOE’s short videos about the challenges still facing LEDs and OLEDs). The networking reception, which featured 60 posters showcasing cutting-edge SSL research projects, buzzed like a beehive for hours.

With all of the progress that’s been made over the past decade, it’s important to keep in mind that it’s still very early in the game, and that we’re a long way from achieving SSL’s full potential in terms of lighting performance, efficiency, adoption, and energy savings. In fact, we’re just at the beginning, which is why DOE continues to support SSL R&D in a variety of ways, including holding this workshop. The input we got in Long Beach will help us update our SSL R&D Plan, which is widely consulted by industry and government and charts a roadmap to propel SSL forward, breaking one technological barrier after another and securing a recognized leadership role for the United States in this transformative technology.

DOE forecasts that SSL has the potential to slash energy consumption for lighting by 75% by the year 2035, lowering U.S. electricity bills by $50 billion annually. But this will only happen if we keep our feet on the accelerator so that the present barriers are overcome. That’s why we gathered in Long Beach. The workshop presentations are posted on the DOE website, and will soon be followed by the highlights.

Product Monday: Amica 2 Recessed LED Luminaire by Focal Point

Focal Point Amica 2 is a new recessed luminaire designed for shallow plenum applications, targeting price sensitive new construction or remodel projects. Amica 2 is the next generation of Amica, featuring a superior angular housing, very high efficacy, and enhanced control features.

The luminaire is available in 2×2 and 2×4 sizes with multiple mounting options: recessed, suspended and surface in order to fit in a variety of ceiling types, providing flexibility for diverse spaces. Light output ranges from 2,000 to 6,000 lumens with up to 140 lumens/W, meeting the stringent energy efficiency standards of the DesignLights Consortium (DLC) Premium status. Retaining the classic aesthetic of the original, Amica 2 complements architecture and brings visual harmony to commercial spaces.

Maintenance and serviceability are simplified with below-the-ceiling access of LED boards and drivers, while integrated Connected Solutions allow for operational building management. Amica 2 is the first Focal Point luminaire to feature Connected Solutions, a wide range of third-party sensors, drivers and other components that allow for integration with wired and wireless networks and building control systems.

Click here to learn more.

Trends in Outdoor Lighting

Below is my contribution to the April issue of tED Magazine. Reprinted with permission.

Outdoor lighting has proven a key market for LED sources due to their durability, directionality, efficiency, longevity, color and optical control. While metal halide and high-pressure sodium remain predominant in the installed outdoor lighting base, LED has captured a majority of luminaire sales. Some LED luminaires emit equivalent light output as a high-pressure sodium luminaire for one-third or less of the energy.

According to the U.S. Department of Energy (DOE), LED achieved a 10 percent penetration of the installed base, which increased to 18 percent in 2015. DOE forecasted penetration to increase to 66 percent by 2020. As with other markets, in outdoor stationary, DOE expects an initial uptake in LED replacement lamps followed by their decline relative to LED luminaires. More than 9,200 LED outdoor lighting products are listed in the DOE Lighting Facts database, nearly half of which satisfy the efficacy and output requirements of the DesignLights Consortium’s Qualified Products List.

This article focuses on four major trends in area and roadway luminaires.

Major trends

As the LED outdoor lighting market matures, a number of trends are asserting themselves beyond the core trend of improving source light output and efficacy. These include an emphasis on visual comfort, shift in color temperature, and controllability.

Increasing efficacy.
From the beginning, the lighting industry’s primary focus has been to improve source light output, which increases efficacy while reducing materials and cost. LED outdoor area products listed in Lighting Facts show a wide range in output, from less than 500 to more than 125,000 lumens, to satisfy a broad range of applications. They also show a wide range in efficacy, from 20 to 150 lumens/W, with a mean efficacy of 93-98 lumens/W. DOE forecasts that outdoor LED luminaires may reach a mean efficacy up to 105 lumens/W by 2020, while cost may decline to $25/kilolumen.

Visual comfort.
Manufacturers say their customers are becoming more concerned with visual comfort, expressed as a desire to eliminate LED pixelation—individual bright LEDs being visible to users. This is particularly a concern with luminaires mounted at lower heights.

“The biggest concern with pedestrian-scale LED luminaires is that they present distracting pixelated images and poor visibility,” says Scott Teschendorf, Market Development Manager, Eaton.

Nonetheless, glare is subjective, which means eliminating pixelation does not guarantee visual comfort. The product must still be evaluated for visual comfort, which is based on its optics.

Color temperature. The industry’s focus on maximizing light output and efficacy emphasized higher (“cooler” or bluish-white) correlated color temperatures (CCTs) over warmer CCTs, due to higher CCT’s higher efficacy. In the early years of LED outdoor lighting, the predominant choice was around 5700K. Today the gap in light output related to CCT is diminishing. Looking at the Lighting Facts data for area and roadway luminaires, for every 1000K increase in CCT, efficacy increases 2.7 lumens/W, meaning a 3000K source is about 5.4 lumen/W less efficacious than a 5000K source.

The shrinking gap in output has led to demand for warmer CCTs. The Lighting Facts data shows about half of listed area luminaires have a CCT of 5000K or higher, 37 percent with 4000K, and 12 percent with 3000K or lower. In 2016, average CCT declined 150K, suggesting a shift to warmer sources.

“With respect to color temperature, 3000K and 4000K CCT demand was generally limited to more architectural applications,” says Andy Miles, Director of Product Marketing, Outdoor Lighting, Hubbell Lighting, Inc. “However, with the efficacy penalty of warmer-CCT LEDs becoming less impactful, many customers in our commercial markets previously selecting 5000K LEDs are now opting for 4000K.”

In 2016, the American Medical Association (AMA) issued community guidance cautioning against poor outdoor lighting, which AMA said can produce detrimental health and environmental effects. Specifically, AMA cautioned against glare, which can affect safety, and very cool CCT LEDs, which can suppress melatonin production. To address these issues, AMA recommends 3000K sources, luminaire design that minimizes glare and light trespass, and dimming during off-peak operating periods. As a lighting technology, LED has advantages toward accomplishing these goals, though the guidance toward 3000K sources proved controversial in the industry.

“We believe our customers need to evaluate a wide range of factors including light distribution, energy efficiency, recommended light levels and more in selecting the appropriate product,” Teschendorf says. “For customers who choose to prioritize the AMA’s guidance, Eaton has products available to meet that. Because of this, it has actually had little impact on product development aside from creating the possibility of a shift to more 3000K LEDs in our supply chain.”

Image courtesy of Eaton.

Many states have adopted commercial building energy codes requiring both automatic shutoff (photocell or time switch) and light reduction (time switch or occupancy sensor) afterhours for dusk-to-dawn lighting such as area lighting. As a result, controls are increasingly being applied to outdoor lighting systems.

In 2014, the ANSI C136 Roadway Lighting Committee, in cooperation with NEMA, developed ANSI C136.41. This document describes a standardized seven-pin receptacle and photocontrol, which supersedes the traditional NEMA twist-lock photocontrol featuring three pins used to turn the luminaire ON or OFF. The new standard builds upon the core three pins by adding four low-voltage pins, two of which are used for dimming and two that can be used for occupancy sensing, power monitoring, two-way communication with other devices, etc.

“Incorporating the ANSI C136.41 receptacle into outdoor lighting gives just about everyone significantly more flexibility with regards to integrating controls, whether it is today or in the future,” Miles says. “Fully integrated control systems offer an aesthetic advance and can lower the initial acquisition cost but also lock the contractor or end-user into one standard. The ANSI C136.41 design positions the control equipment outside the luminaire, simplifying maintenance and allowing luminaire selection and maintenance to occur independent of the control selection.”

Microprocessing technology has miniaturized to an extent that lighting controllers can be embedded in controls connected to outdoor luminaires. This enables programming of luminaire behavior and more sophisticated control, such as dimming and color tuning by time of night. Meanwhile, wireless communication facilitates remote command, diagnostics and data collection, which can be useful for management, maintenance and analysis. Protocols include ZigBee, Synapse Network Appliance Protocol (SNAP), Bluetooth, Wi-Fi, cellular, LPWAN/LoRa, proprietary and others, with ZigBee being most popular.

Miles recommends that distributors ensure that an outdoor LED product’s sales claims be substantiated with industry-standard performance data and test reports (LM79, LM80, etc.). Pay attention not just to light output but pattern—where the light is going—as well-designed luminaires can produce less light but still achieve the same light levels. He adds that distributors should invest in developing in-house lighting specialization and education. “Be sure the generalists in your business can identify opportunities then bring them to your specialists,” he says. “The lighting specialists will get into the details, help specify the correct product for the application and ensure your customers’ needs are met.”

Final word

“LEDs have been lighting the outdoors for 10 years now and have been a proven light source in thousands of projects around the globe,” Teschendorf says. “Because LEDs have the ability to dim, be controlled and perform at high levels, they are a natural fit in order to adapt to the new codes that are here. We are really only scratching the surface of what controlled lighting can bring to the outdoor space. Controls will allow many more value propositions to be addressed than just the physical light itself.”

2017 Lighting Outlook

tED Magazine recently published a lighting supplement that featured a 2017 Lighting Outlook, based on surveys conducted by the magazine and LightNOW of lighting manufacturers, electrical distributors and electrical contractors. The results show a positive outlook for the year among all three market segments (example manufacturer results shown below).

Click here to check it out.

DOE Publishes CALiPER Snapshot on LED Industrial Luminaires

The U.S. Department of Energy’s CALiPER program has released a new Snapshot Report on LED industrial luminaires, based on DOE’s Lighting Facts database. Key findings:

• The efficacy of LED industrial luminaires is notably higher than what’s typical of their incumbent counterparts. About 23% of the industrial luminaires listed with LED Lighting Facts listed products have a luminous efficacy greater than 130 lm/W, the minimum threshold for DLC Premium.
• Listed industrial luminaires have higher efficacy performance than listed linear, troffer, area/roadway and parking garage fixtures.
• Color and power quality for listed industrial luminaires is similar to that of their conventional counterparts. The listed products have a variety of CCTs, with the majority (51%) at least 5000K, and 65% of the luminaires have a CRI in the 80s.

Click here to get the report.

Color Study Challenges CRI

My contribution to the April issue of ELECTRICAL CONTRACTOR presents TM-30, the proposed method for evaluating color rendering and saturation, and describes a recent study that suggests saturation is critical to truly evaluating color quality. Specific gamut shapes may be critical to modeling human color preference.

The study found that Rf is a good predictor for how normal colors appear, while Rg is a good predictor for perception of saturation. Neither alone, however, proved a good predictor of preference. This means that, even if two light sources have the same Rf and Rg values, they can result in very different subjective impressions. Participants showed a distinct preference for saturated reds. This indicates specific gamut shapes are more important than Rf and Rg in modeling preference.

Interestingly, a majority of the most favored sources had CRI values below 73, a range normally considered fair or poor in color rendering. The CRI metric significantly penalizes increases in red saturation, which results in light sources engineered to achieve a certain CRI but with less-preferred gamut shapes. Most energy-efficient lighting available today does not saturate reds.

Check out the full story here.

Product Monday: ArcLamps by ETC

The ArcLamp from GDS by ETC was redesigned to allow auditoriums and similar venues to save energy without compromising on aesthetics or audience experience. ArcLamp, like all ArcSystem products, provides LED lighting specifically engineered to fit the needs of auditoriums and performance venues.

These compact, 4.4W LED lamps can replace traditional, 40W lamps in a variety of applications, from modern installations to historic chandeliers. The lamps available in 2700K and 3000K color temperatures, medium-screw (E26) and candelabra (E12) bases, and clear and frosted candle and globe forms.

Since most shows start with a slow fade to black, ArcLamp’s drivers dim the emitters smoothly all the way to zero.

Click here to learn more.

Amazon Poised to Disrupt Electrical Distributor Industry

In an interesting blog post at, Nicholas Johnson states:

Amazon Business head Prentis Wilson has openly identified Industrial Supply as a target for Amazon’s growing B2B marketplace. But one industry segment in particular stands out as ripe for disruption: the $160 billion electrical distribution industry.

The reason:

While other industry segments like electronics distribution typically involve a lot of custom orders and closer cooperation between distributors and manufacturers, many of the goods sold in electrical distribution are essentially commoditized.

He points out there are 15,000 electrical distributors in the United States within a highly fragmented marketplace in which the large majority are smaller players.

Says Johnson:

A company like Amazon has the resources and logistical services to attract a large number of small sellers very quickly. Once Amazon has the breadth and depth of inventory that these small suppliers can offer, the marketplace can begin to compete with the major distributors on price and quality.

One option for the larger distributors is to create their own marketplace, as this market strategy is less capital-intensive and faster than consolidation. Johnson concludes:

Who will own this opportunity in electrical distribution is not yet certain. But with industry demographics pointing toward a strong marketplace opportunity, the current structure of the industry will likely not last for long.

Check out Johnson’s blog post here.