Stories Color-Tunable Sources Make for Artful Illumination
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Color-Tunable Sources Make for Artful Illumination

From Architectural SSL

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Illuminating great works of art is not a task to be taken lightly, especially at the Art Institute of Chicago, which was ranked as the top museum in the world by the Trip Advisor 2014 Travelers’ Choice Awards. In keeping with the museum’s outstanding reputation for excellence, the lighting designers at Lightswitch Architectural have been working with AIC since early 2014 to develop innovative LED solutions and standards for the museum.

“Energy savings was the main goal, but more important was what was discovered—that we could maintain the look of the art for a long period without needing to re-lamp the luminaires,” says Avraham Mor, partner in Lightswitch’s Chicago office, about the quest for integrating cutting-edge LED solutions at the AIC. “So main- tenance became the bigger issue as we reviewed all our options.”

In exploring LED, Mor says the team found that they could significantly reduce labor costs associated with re-lamping, the cost of replacement lamps, and mistakes that frequently happen during re-lamping, such as improper accidental refocusing, as well as lamp degradation.

Work focused on three parts of facility: the Modern Wing, the Japanese Galleries and the soon-to-be redesigned Medievel and Monet gal- leries—the focus of this article. In the process, Lightswitch discovered a ground-breaking, digital, color-tunable LED lamp that could also be used to retrofit other gallery and exhibit spaces in the future: the PAR38 LED lamp from Ketra.

According to Mor, sources that are color tunable are game-changers because it gives the institution’s curators the ability to fine tune the CCT and intensity of each source to complement the color and finish of the art or object being illuminated—all via digital controls. “This is a new approach for museums,” says Mor. “And we spent a great deal of time working with the curatorial staff at AIC to ensure that the LED sources could achieve the proper color and effect.”

Several mock-ups, in fact, were required to match the color between LED sources. The initial mock-up focused on the museum’s displays of religious paintings and medieval armor. After proving successful, Lightswitch arranged a side- by-side mock-up that compared AIC’s existing sources with its preferred LED option from the first trial.

Through detailed research and in-depth testing, the designers found a color-tunable, high-CRI LED source that not only would reduce the Art Institute’s energy use and maintenance, but will also enable it showcase its art in the best possible light.

“We illuminated two paintings in Claude Monet’s ‘Haystacks’ series with PAR38 LED lamps from Ketra, while the others remained lit by incandescent PAR38s and MR16s,” explains Mor. “To ensure the ideal color temperature and rendering were achieved—a must for fine art installations—we color tuned the Ketra sources to match the incandescent lamps and then com- pared the CRI, illuminance levels and spectral power distribution of the sources.”

Twenty AIC staff, including art curators and the museum’s CEO and COO, analyzed the results and selected the LED option. “There are colors in the paintings that appear more ‘correct’ with the LED source. The most vibrant of these have been some of the blues and purples. The LED sources produce an enhanced effect with these colors that incandescent lamps just cannot produce,” Mor notes.

The Monet paintings are currently controlled by the most basic control system: a breaker panel. In this space, Mor says the team installed the Ketra PAR38 LED lamps into the existing track heads. Using the manufacturer’s Design Studio software, lights were then dimmed and the color was adjusted as needed. “We matched color of the existing lamps using a Sekonic C-700 meter, then further adjusted it to the curators’ liking with our eyes,” notes Mor.

Factoring Flicker
To achieve ideal footcandles, the levels had to vary. “A typical range would be 5fc-15fc, but each object type has a different curator and different light level rules,” says Mor. “For example, the Monets have 10fc and the wall beyond has 15fc. But the key with LED sources is providing the right level of illumination with no flicker.”
Yet one continuing challenge is indeed flicker. “During mock-ups we found the same product flickered in one wing of the building, but not an- other,” Mor points out. “This has caused us to use only digital dimming and has rectified the issue of relying on clean power.”

Another issue Mor says designers must ac- count for is intensity. “There is a race to brighter and brighter LEDs, but we don’t need them to be brighter in all cases. At times we find sources to be too bright, and when dimmed, they do not dim down low enough!”

Still, Mor plans to continue experimenting with SSL sources in the facility, but using them judiciously where they make sense.