Shedding light on LEDs

Luminaires that include light-emitting diodes offer nearly endless creative possibilities for facilities.

By Aram C. Ebben, LEED AP; and Matt Hopf, PE, LEED AP, exp, Maitland, Fla. April 12, 2011

As technology in the lighting industry has advanced over the past several years, light-emitting diode (LED) sources have begun to make up a larger portion of the business. LEDs are becoming more cost-effective, brighter, and more efficient. At the same time, energy codes are becoming more restrictive. Both owners and designers are realizing the significant benefits LEDs can provide. 

Another benefit that often is overlooked is the ability of designers using LEDs to create custom, dynamic, themed spaces within facilities. With their inherent dynamic abilities, luminaires using red-green-blue (RGB) LEDs offer designers seemingly endless creative possibilities. The use of luminaires as “themed elements” not only eliminates the need for some of the architectural elements, but also provides the ability to create dynamic, ever-changing spaces.

The Jets & Giants Team Store at the New Meadowlands Stadium, East Rutherford, N.J., and the Harrah’s Cherokee Casino Expansion, Cherokee, N.C., are two cases in which RGB LEDs have been used in different applications. Both designs achieve the same result: a dynamic color-changing environment that serves the needs of the owner and enhances the customer experience. With a little care and creative vision, RGB LEDs can be used in virtually any environment to enhance the design and create a compelling experience.

The Jets & Giants Team Store 

The main challenge in designing the new Jets & Giants Team Store was that both teams occupied not only the same stadium, but also the same retail space. Charged with creating a space that served each team uniquely, the design team decided that the best way to accomplish this would be through the use of color-changing light. By “painting” the white ceiling and walls in the space with either blue or green light (team colors), the entire lit environment could be changed at the push of a button.

Other challenges for this project included a tight lighting, mechanical, electrical, and plumbing (MEP) budget from the owner, and existing MEP utilities installed under the main stadium build-out. The challenge for the store was the amount of audio-visual (AV) equipment involved. Within the store, there were more than 30 televisions, 18 projectors, a ticker display (to show live scores), interactive games (EyeClick system, PlayStation systems, etc.), and more than 20 point-of-sale stations. All of these electronics required a lot of power and a lot of cooling. In addition, the low-voltage head end systems for these AV systems required more power and additional cooling. To help offset some of these AV power and cooling needs, the lighting design needed to be energy efficient; cooler LEDs were the natural fit.

Executing the design turned out to be a significant challenge because the budget, space, and energy usage limitations prevented the use of “off-the-shelf” technology. However, contrary to conventional wisdom (the use of standard fluorescent luminaires), with a little careful planning and a willing partner in the manufacturing process, the custom LED option can be the most efficient and cost-effective one. To light the ceiling, the design team decided to turn to a custom LED fixture manufacturer, Light Integration (LI), of Longwood, Fla.

Using a variation of LI’s Norma bar platform (referenced as Norma 2), the standard single-color LED layout was increased to two colors, wherein the driver circuit was used to power either the green or the blue LED runs. Using an onboard electronic relay, LI was able to direct the driver output to either the blue or the green series of LEDs (thus eliminating the need for two drivers). Onboard drivers are used in both the Norma and the Norma2 boards for the following reasons:

  • Local driving promotes consistent output between strings of LEDs regardless of the LEDs’ distance from the power source.
  • Localized circuitry allows for electronic compensation of small groups of LEDs, which helps equalize output within the LED bin variations.
  • Potential failures are localized to each 16-in. board length.
  • Onboard drivers allow for the installation of longer runs while not being concerned with voltage drop.
  • Installation is easier and less costly.

Due to their high quality and consistent binning (the process of grouping LEDs with similar characteristics on the same reel/fixture), Cree XP-E LEDs were used for both the blue and the green channels.

The standard length of the Norma2 is 16 in., which allowed for six green and six blue alternating LEDs. Spaced at 1.3 in. between each LED meant that spacing between each like color was a manageable 2.6 in. This was important due to the relative close proximity of the ceiling to the Norma2 bar. Each 16- in. fixture used approximately 16 W per color (700 ma current at the LED). This equates to approximately 12 W for either color with each LED being driven at what is commonly called a 3-W output.

The advantage in the Norma2 system was one shared platform, driver, and thermal management system across two colors. The trade-off was an additional signal wire and transformer, instead of two fully redundant systems, or a system of three colors with only two being employed. The additional advantage of the single driver circuit allowed the fixture to be rated at just 16 W maximum rather than the 32 W maximum with two independent channels. The low power consumption of the LED fixtures in the space was critical to the design as the W/sq ft allowance for the project, a retail space in New Jersey, is 1.5 W (ASHRAE 90.1- 2004).

The blue and red linear accents in the architectural stripes were controlled in a similar way using a standard product with a custom controller. The Ceres RGB LED tape by LI was controlled using a single power supply for the red and green channel of the tape. Low-voltage relays installed on the secondary outputs (12 vdc) were triggered by another 12 vdc signal generated by the control system. At 5 vdc the trigger voltage on the mechanical relay kept the line loss manageable where present.

Due to the tight project budget, a central dimming system and dimmable LED drivers were not options, so controlling all the lighting fixtures within the retail store was a Lutron XPS relay panel, five-button keypad, cycle timer, and contact closure (see Figure 1). To simplify the operation, the local five-button wall station allowed the staff to change the entire look of the store from “Jets” to “Giants” to “Alternate” to “Cleaning” and to “Off.” The “Alternate” function was requested by the owner for when the store was open during the week (nongame days) and cycled between the “Jets” and “Giants” looks.

Harrah’s Cherokee Casino

Casinos are a natural environment for LEDs, which have been used in gaming machines for years. In addition, LEDs can be used to provide themed and general lighting throughout a casino for illumination. Working closely with the architects and designers from Cuningham Group Architects, RGB LEDs were used to create a custom, dynamic, color-changing luminaire Wind fixture, which is more than 500 ft long, 1 ft wide, and up to 8 ft tall.

Emulating the abstract nature themes that define the various spaces of the casino, the wind fixture follows a serpentine path throughout the new/remodeled casino, transforming the core path in each space via a colorful and dynamic light show.

Construction of the mammoth fixture was assigned to Lukas Lighting, which worked closely with the design team to build a fixture that could be handled easily, maintained efficiently, and cleaned regularly. Besides the obvious color-changing ability, the fixture needed to be bright enough to project light more than 20 ft through a custom screen printed over the acrylic enclosure to create a literal path of light on the floor. ColorGraze Powercore fixtures from Philips were selected as the light engine of choice due to their robust construction, intense brightness (more than 271 lumens/ft), and low energy consumption (only 17.5 W/ft). For optimal flexibility, the fixtures can be controlled in 1-ft segments. This kept the overall number of DMX channels to a relatively manageable 1,500 spread over three universes.

Designed for 24-hour operation, the lumen maintenance offered by the LED fixture is superior to other lamp sources. An 80,000-hour life (at 70% lumen depreciation) ensures that the fixtures will be able to operate continuously for more than 9 years. The long life of LEDs is an important advantage to casinos or other facilities that are open 24/7 throughout the entire year. Because the fixture is located high above the main gaming floor path, replacing the LEDs will require lifts and a shutdown of that particular area of the casino— not something casino general managers ever want to hear.

Electronic Theatre Controls was selected to provide the control system for the entire casino, including the Wind fixture. Using the company’s Mosaic controller, multiple dynamic light shows were recorded, allowing the Wind to respond to discreet triggers such as celebrations or jackpots, or to operate independently via an integral architectural time clock.

The use of LEDs within the fixture and throughout the casino helped lower overall lighting power consumption needs and lighting cooling load requirements. An additional challenge facing the design team was coordinating other MEP utilities around the massive fixture. Due to its height, only smaller duct runs could be installed above the fixture. When a large duct needed to cross the fixture’s path, that location was coordinated with the lighting design team so that the large duct run was located within one of the breaks of the fixture layout.

As the lighting industry evolves, LEDs will continue to play a more prominent role in the design of not only themed spaces but everyday buildings. As LED fixtures adapt to the different needs of buildings and designers, they will allow for more drastic and dynamic designs. LEDs allow designers not only to provide illumination within spaces but also to provide unique, dynamic designs within buildings to both highlight architecture and provide their own “wow” elements that make spaces stand out. It’s safe to say that the future of LEDs in the building industry is very “bright.”

Ebben is principal and director of lighting design. He provides creative direction and overall project management for exp’s lighting design group. Hopf is project manager/electrical engineer, and his responsibilities include project management and electrical power and lighting design of casinos, hospitality venues, and other highly technical facilities.