Lighting in Museums

This time-lapse video reveals lighting techniques used to light the gilded age galleries at the Smithsonian Art Museum. By turning lights ON one layer at a time, the layers and their purpose are revealed.

LED Lighting in Museums Part 3

The Lunder Conservation Center held a one-day symposium on LED lighting in museums in March 2013, which included a series of presentations by museum and lighting specialists. Here’s Gordon Anson, chief lighting designer for the National Gallery of Art.

OSRAM to Separate Lighting Business

The Board of OSRAM Licht AG has announced that it intends to transfer its general lighting/lamps (including both traditional and LED) business into an independent legal structure.

In fiscal 2013/14, this business generated worldwide sales of about 2 billion euros. The independent legal structure is to provide the basis for the further development, while also considering partnerships.

LED Lighting in Museums Part 2

The Lunder Conservation Center held a one-day symposium on LED lighting in museums in March 2013, which included a series of presentations by museum and lighting specialists. Here’s Naomi Miller of PNNL.

LED Lighting in Museums Part 1

The Lunder Conservation Center held a one-day symposium on LED lighting in museums in March 2013, which included a series of presentations by museum and lighting specialists. Here’s Scott Rosenfeld, lighting designer with the American Art Museum and Renwick Gallery.

Product Monday: BeveLED 2.0 FLAT Downlight by USAI

USAI Lighting’s BeveLED 2.0 FLAT downlight measures less than 4″ tall from the finished ceiling plane to the top of the housing and presents a 2-3/4″ housing height in the trim version and a 3-3/8” tall housing height in the trimless, providing design flexibility.

The downlight emits up to 2,350 lumens at up to 84 lumens/W. It is available with multiple dimming driver options and features a custom-designed heat sink for good thermal management. The luminaire is serviceable through the aperture, enabling easy tool-less field replacement of light engines and drivers.

Click here to learn more.


CEOs Upbeat on Economy

A first-quarter survey by the Business Roundtable indicates CEOs expect U.S. GDP to increase 2.8% in 2015, up from 2.4% last quarter.

Reuters has the story here.

Brodrick on LED Lighting in High-Temperature Environments

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

doeHigh-flux lighting applications in high-temperature environments present a formidable challenge for LEDs. The higher the luminous flux from a luminaire, the more difficult it can be to properly dissipate the heat, to prevent damage to the electronic components and LED packages; and this is made even more difficult by high-temperature environments. To learn more about how this type of environment affects LED lumen and color maintenance, luminaire efficacy, and luminaire component lifetimes, DOE’s GATEWAY program is documenting the LED retrofit of the incumbent quartz metal halide (QMH) area lighting along a 7.2-mile stretch of the Yuma (Arizona) Sector Border Patrol Area between the U.S. and Mexico, where temperatures at sunset can exceed 100° F. Although a border lighting application is unique, high-flux and high-temperature applications are not, and in the U.S. they include high-security exterior lighting (e.g., correctional facilities and military bases) and, more generally, street and area lighting.

The Yuma Sector retrofit is a DOE Federal Energy Management Program (FEMP) Energy Savings Performance Contract (ESPC) ENABLE project administered through the General Services Administration (GSA). Through the ESPC ENABLE process, an energy service company (ESCO) was selected for the retrofit, and Eaton’s Cooper Lighting Business designed the lighting system and manufactured the luminaires. The goal was to achieve a minimum energy savings of 50% while maintaining existing light levels, and the application also presented an opportunity to improve lighting quality.

The specific area of interest was between the primary fence marking the U.S.-Mexico border, and a secondary fence set back 125ʹ from the primary fence. This spacing between the primary and secondary fences, coupled with 180ʹ pole spacing, required each LED luminaire to cover roughly 11,250 square feet with an approximate average illuminance of 25 lux (lx) at a 40ʹ mounting height.

The ESPC ENABLE process required an investment-grade audit, which was conducted in February 2014. Two LED luminaires were installed on each of three sequential poles as a trial demonstration of the proposed design solution for U.S. Customs and Border Protection (CBP) approval, prior to the task award. A new GATEWAY report presents the initial findings from this trial demonstration and is the first in a planned series that will document the installation of LED luminaires throughout the Yuma Sector. The final system design and luminaire selection by CBP are ongoing.

In the trial demonstration, the new LED system was found to equal or better the QMH system in terms of both uniformity and illuminance, when comparing the initial output of the LED system and the maintained output of the QMH system, which had been operating for an unknown number of hours. The average illuminance of the two systems was comparable, with the LED system exceeding the QMH system for all horizontal illuminance measurements taken between the primary fence and the pole, and for vertical measurements taken on the primary fence. The vertical illuminance on the primary fence increased by more than 100% with the LED system, relative to the QMH system. The average horizontal and vertical illuminance on the secondary-fence side of the pole was slightly lower with the LED system than with the QMH system.

Night is when the most activity occurs in the Yuma Sector Border Patrol Area, so it was important to ensure that the lighting system would help the agents perform their duties. The LED lighting system installed for the trial demonstration confirmed LED technology’s ability to reduce energy consumption and improve lighting quality. That lighting system had been on the market less than two years, yet at the time of installation, an upgraded system that incorporated a newer-generation LED package was due to come on the market within the next several months. That upgraded lighting system provided improved efficacy and optical distributions, requiring lighting system design modifications that resulted in an expected energy savings of 69%.

The expected annual maintenance cost savings include considerable reductions in maintenance visits required by the contractors as well as savings in CBP staff time and resources. The retrofit includes a 24ʹ reduction in pole height, which increased projected energy savings due to a reduction in lumen output required at a lower height, and decreased expected annual cleaning costs due to reduced lift and labor costs. The advanced optical system of the selected luminaires improved the uniformity of the lighting system, despite the reduction in pole height. The combination of the optics and lower pole height reduced stray light considerably.

The Yuma Sector Border Patrol Area lighting retrofit trial demonstration displayed the potential of LED technology to improve lighting quality and reduce energy consumption. DOE plans to continue to track the progress and performance of this installation over the coming months. If high-flux LED technology performs well in a region with high ambient temperature and solar radiation, it can perform well in most outdoor environments.

For details on this project, see the full report, which is available on the DOE website.

Trends in LED Indoor Luminaire Design

I wrote this article for the March issue of tED Magazine. Reprinted with permission.

The year 2014 represented a major milestone in adoption of LED technology in terms of demand and product design.

With energy savings as high as 30-40 percent (not including additional control impacts), long rated life (with the promise of little or no spot relamping), and ongoing cost reduction, LED continues to gain in popularity. It is attractive not only in new construction—particularly in building designs regulated by more stringent energy codes—but also relighting projects offering attractive economics.

In November 2014, a survey was distributed to 1,679 lighting manufacturers subscribing to the author’s LightNOW newsletter, with a 4.7 percent response rate. Respondents at companies manufacturing indoor luminaires with a mix of conventional and LED sources were isolated. The average respondent in this group reported that 45 percent of their U.S. indoor luminaire unit sales as of that time in 2014 were LED-based.

Today, LED luminaires are competing for virtually every interior application. “At this point, virtually every project now quotes an LED option, especially for environments where dimming is required, and LED solutions are approaching cost parity with traditional sources,” says Kraig Kasler, Vice President and General Manager, Indoor, Eaton’s Cooper Lighting business. “In the commercial space, we are seeing a lot of customers purchase LED troffers, strips and downlights. In the industrial space, given the maintenance advantages, we are seeing a significant transition towards LED high-bays. Now that LED fixtures have been developed that cover the basics of good lighting design—general, task, accent and wallwashing—most indoor applications are covered.”

“Hubbell Lighting’s overall adoption of LED luminaires is quickly approaching 50 percent,” says Chris Bailey, LC, LEED AP BD+C, DDI, MIES, Director, Lighting Solutions Center, Hubbell Lighting, Inc. “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.”

As LED technology matures, the overall product offering will continue to stratify in a way consistent with traditional lighting. “Trends in indoor LED luminaire design may accelerate the segmentation of the LED-based luminaire market into a ‘white goods’ segment and a ‘tailored lighting’ segment,” says Terry Clark, Chairman, Finelite, Inc., who estimates that more than 70 percent of new construction and major remodeling projects incorporate LED products. “The white goods segment will deliver more performance in lumens per watt at lower cost and require successful companies to be volume leaders. The tailored segment will need to reduce lead times to meet more project requirements and provide cost-effective ways to make the specifier’s vision a reality.”

Bailey agrees, adding, “Some degree of stratification has already occurred in the lighting marketplace. This is consistent with the conventional lighting marketplace, where products can be categorized as commodity, specification or somewhere in between. In other words, LEDs are now equally relevant for almost any application—not just the specification market.”

Image courtesy of Columbia Lighting.

Image courtesy of Columbia Lighting.

New form factors and optics

Conventional luminaires were designed around the physical dimensions of those light sources. Early generations of LED luminaires attempted to incorporate early LEDs into essentially the same design. Many new LED luminaires are taking advantage of the LED as a very small light emitter to reduce luminaire size and create new form factors.

“The fundamental rule of optics is the larger the emitter, the larger the optic,” says Tim O’Brien, Commercial Office Practice Director, Acuity Brands Lighting. “The beautiful thing about LEDs is that the emission is very small. It gives the designer such flexibility.”

As efficiency and thermal performance in LED packages continue to improve, fewer LEDs may be needed to satisfy light levels and optical distributions. This allows even greater flexibility in optical and mechanical design. An example is new flat surface-mounted LED downlights that mount directly to the junction box, protrude an inch or less from the ceiling, and provide similar light output and appearance as recessed downlighting, ideal for applications where ceiling clearance can be an issue.

“This has been one of the truly exciting aspects of the transition to LED,” says Kasler. “Lower wattage will lead to smaller fixtures, which will continue to allow for smaller apertures with higher lumen potential. With the new light sources, we have been able to design to new form factors—smaller, lighter, thinner, edge-lighting—and this trend will only increase, especially as thermals become less and less of an issue over time.”

Clark points out that miniaturization facilitates the design of shapes that include complex angles and custom lengths, allowing designers greater flexibility and giving the ability to solve a wider range of design challenges.

“LED luminaires have the unique ability to transcend traditional luminaire design and break new ground,” Bailey says. “LEDs can be incorporated directly into the fabric of a luminaire concept. Flexible and translucent circuit board technologies provide the ability to move luminaire designs from routine, predictable and rigid forms into an era of freeform design without rules of scale, size and structure.”

Clark says the only thing holding back the potential of this capability is the traditional construction process. “New form factors are coming,” he notes. “However, it is important to remember that many projects require that an ‘equal’ luminaire be available from more than one lighting manufacturer. To the extent this continues, most unique shapes will likely remain decorative luminaires that service market niches.”

The directional emission of LEDs, meanwhile, has also sparked the development of optics that go beyond traditional reflectors designed around omnidirectional traditional sources. The most common is TIR optics, typically constructed of injection-molded acrylic and for which optical efficiencies greater than 90 percent are possible. Some luminaires combine TIR optics with reflector-based optics to optimize both visibility and visual comfort.

“Not only are TIR optical systems efficient at transmitting light into the space, they uniquely enable the precise placement of light within a space,” Bailey says.

Other developments have been made in edge lighting, light guides and micro or imprinted optics, in which complex optical structures are created on thin optical sheets or films that facilitate transmission, diffusion and optical control.

“Refractor optics potentially offer the ability to improve optical efficiencies substantially, while touching more of the light, which further translates to getting more of the photons to where they need to be in the application,” Kasler says.

Smaller LED packages facilitate the design of shapes that include complex angles and custom lengths, allowing designers greater flexibility and giving the ability to solve a wider range of design challenges. Image courtesy of Finelite.

Smaller LED packages facilitate the design of shapes that include complex angles and custom lengths, allowing designers greater flexibility and giving the ability to solve a wider range of design challenges. Image courtesy of Finelite.


The latest generation of energy codes require highly efficient, bilevel lighting, favoring LED that is not only low in power but also often offered with 0-10V dimming control standard. One of the most exciting trends in indoor luminaire design is intelligent (digital) control, allowing a wide range of capabilities:

• Luminaires can be individually zoned and/or zoned in groups, later rezoned, and calibrated using software.
• Luminaires can be programmed to produce constant light output over the life of the luminaire, generating additional energy savings while potentially extending product service life.
• Luminaires can be programmed with custom wattage and light output settings to satisfy precise design requirements.
• The white light emission of the luminaire can be precisely tuned to satisfy the application needs after installation, and can be configured to change dynamically based on time, user preference or other inputs.

Sensors and controllers may be integrated within the luminaire and may communicate using dedicated control wiring or wirelessly using a radio frequency.

Final word

“Similar to consumer electronics from five years ago, we are just scratching the surface of the value that we can provide,” O’Brien says. “We will see better integration of building systems, the ability to personalize, new form factors. Everything will change in the next five years.”

Whiter Than White

I wrote this article for the April 2015 issue of tED Magazine. Reprinted with permission.

From walls to paper to plastics to clothing, white abounds in the built environment. Lighting research, however, has focused on the rendering of colors. The color rendering index (CRI), in fact, is based on the rendering of colors by a white-light source and does not characterize how well the source renders white.

To manufacturers of white materials and goods, white matters. Many manufacturers use fluorescent whitening agents (FWAs) to make objects appear “whiter than white.” These agents (which incidentally occur naturally in some natural materials, such as human teeth) absorb ultraviolet and violet light and re-emit blue light, causing fluorescence and a perception of enhanced whiteness. The degree of enhancement depends on the composition and quantity of the FWA.

An object is not visible unless it reflects light, however, and the color of objects is entirely dependent on the color composition of the light source. The ability of light sources to render objects accurately is expressed by the source’s CRI rating and color composition expressed using correlated color temperature, measured in kelvins (K). As CRI again does not capture rendering of whites, what’s relevant here is color temperature. This is why a white wall appears different under an incandescent source compared to noon daylight. It is most noticeable when viewing objects illuminated separately by light sources with different color emissions.

Another factor is whether the light emission is capable of exciting the FWA and producing fluorescence and the resulting whiter-than-white effect. Again, for an FWA to fluoresce, the output of the light source must contain a UV or violet component. Incandescent and halogen lamps produce some violet emission. The spectral emission of LED sources, however, is precisely engineered, often with no output below 430 nanometers (violet).

A 2014 study led by Kevin W. Houser at Pennsylvania State University’s Department of Architectural Engineering and funded by LED product manufacturer Soraa, Inc., “Whiteness Perception Under LED Illumination,” explored the issue. The study attempted to determine whiteness perception using three types of psychological experiments (forced choice, selection, sorting) with various amounts of FWAs and under five light sources. The light sources included a filtered halogen lamp, a typical blue-pumped LED and violet-pumped LEDs with three violet emission levels (2.5, 5 and 6.5 percent violent composition in the spectral output). Thirty-nine people with normal color vision participated in the experiments.

The results focused on two effects related to whiteness rendering and perception—chromaticity and the presence of FWAs. Regarding chromaticity, as expected, a blue shift generally produced higher whiteness perception. Regarding FWAs, however, all lamps except the blue-pumped LEDs produced higher whiteness perception values as the amount of FWAs increased.

LED sources with some violet emission excite fluorescent whitening agents used in many white materials and goods, making them appear whiter than blue-pumped LEDs, according to a new study conducted at Penn State University. Image courtesy of Soraa.

LED sources with some violet emission excite fluorescent whitening agents used in many white materials and goods, making them appear whiter than blue-pumped LEDs, according to a new study conducted at Penn State University. Image courtesy of Soraa.

In an article presenting the research findings, published in Leukos, the Journal of the Illuminating Engineering Society, the researchers stated: “The [blue-pumped LED] exhibited serious problems in accurately rendering the calibrated whiteness standards. We would expect similar problems to occur with the many manmade objects that contain FWAs… When the FWAs contained in objects cannot be excited, as is the case with blue-pumped LEDs, observers will be unable to differentiate white objects. This has implications for the illumination of white textiles, plastic, makeup, paints and papers.”

Since the large majority of LED products use blue-pumped phosphors to produce white light, the results are concerning.

Houser et al concluded, “We believe that whiteness rendering should be considered alongside color rendition when evaluating a source’s overall color quality.”