LED Lights Replacement Case Study: City of Centennial, Colorado Saves More than $50,000 a Year

As part of a city-wide sustainability initiative, officials in Centennial, Colorado recently completed a project to upgrade each of the city's traffic and pedestrian countdown signals from traditional incandescent units to Dialight's high-efficiency, low-maintenance ITE-compliant Led traffic signals. The project, funded by the U.S. Department of Energy's Energy Efficiency and Conservation Block Grant Program (EECBG), not only improved visibility for drivers and pedestrians, but is expected to save the city $50,000-$60,000 a year in energy and maintenance costs.

Modern City, Progressive Planning

Appropriately named in honor of its citizens' September 2000 vote to incorporate, the City of Centennial is not only one of the youngest cities in the State of Colorado, but also the safest. With a vibrant community that blends the convenience of city living with the beauty of semi-rural neighborhoods, Centennial has been named Colorado's safest city for six years in a row. Home to nearly 110,000 residents, the city's backdrop against the picture-perfect Rocky Mountain skyline makes it one of the most beautiful in the Great American West.
In a progressive move intended to improve driver and pedestrian safety and reduce energy consumption and expenses, the city has recently completed a full replacement of its out-dated incandescent traffic signal balls, arrows and pedestrian indications with Dialight's ultra-energy efficient ITE-compliant traffic and pedestrian signals.

"Safety, reliability and overall brightness were significant concerns," said Craig Faessler, P.E., City Traffic / Transportation Engineer with the City of Centennial. "But, so were the energy consumption and maintenance costs. An upgrade to all-LED addressed all of these issues."

In addition to the fact that some of the faded lenses were at least 20 years old - as old as the signals themselves- the units consumed an exorbitant amount of energy and demanded nearly continuous maintenance with regular bulb changes to keep motorists and pedestrians safe. After a competitive bid process, Centennial chose Dialight units provided by Traffic Signal Controls, Inc., a Colorado-based Dialight distributor, for their efficiency and affordability.

Dramatic Energy Reduction = Significant Savings

In a two-phase project, fully funded by the EECBG program, the city replaced 1,288 red/yellow/green balls, 142 red/yellow/green arrows and 232 pedestrian countdown timers in Phase One, with the remaining 85 balls, 30 arrows and 1 pedestrian signal changed out in Phase Two.
Replacing the 116W incandescent signals and arrows with energy-sipping 8W LED units and the 59W incandescent pedestrian signals with 6W LED units is predicted to shave 572,000kWh off the city's electric bill, for a total energy savings of $36,000 per year. And, because the LED units will last at least five years-and likely even longer-Centennial expects to save $20,000 in annual maintenance costs by eliminating bulb changes, which also increases safety for signal technicians and motorists by eliminating unnecessary traffic control.
In another sustainability effort, Centennial is converting its school zone beacons to solar power.

"In addition to the energy efficiency, Dialight's products were the most affordable on the market to meet our needs, and the added bonus of the 5-year warranty sealed the deal," Faessler said.

Installation Snapshot
• - Total # of red, green, yellow balls & arrows - 1,545
• - Replaced - 150W incandescent with 8W LED
• - Total # of pedestrian signals - 233
• - Replaced - 50W incandescent with 6W LED
• - 572,000kwh annual savings
• - $56,000 energy & maintance savings

led lights replacement

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Bridgelux adds to RS LED array series, hits 8000 lm

Bridgelux adds to RS LED array series, hits 8000 lm

Bridgelux has expanded its RS LED Array family with new models that reach 5600 lm in warm white and 8000 lm in cool white, and targets market segments such as retail lighting and street lights.

Bridgelux introduced the RS family of LED arrays a year ago, and is now adding products with greater lumen output for solid-state-lighting (SSL) applications. The company has enhanced versions of existing products that boost output 20% while reducing the cost per lumen by 30%, and the company introduced new products that offer light output in the 5600-to-8000-lm range.

The RS family targets applications that demand high-lumen sources. VP of Global Marketing Jason Posselt asserts that customer demand drove the company to create the RS family in which the company packages an array of emitters under a single lens. Target applications include retail-store lighting and LED street lights.
Bridgelux is offering the new members of the RS family in 2700K, 3000K, 4000K, and 5600K color temperatures. The LEDs have a CRI of 82, although the 2700K products can be optionally specified with a 90 CRI. The company is offering 3-step MacAdam ellipse binning.

The RS announcement covers both what are essentially enhancements to existing products as well as some new arrays. The company has boosted the light output of existing RS family members by 20% -- for instance taking what was a 3000-lm warm-white array to 3600 lm. According to Posselt, a combination of improvements in chip, epitaxy and packaging yielded the increased output and a 30% reduction in cost per lumen.

Larger chips

The brand new arrays that range from 5600 to 8000 lm leverage emitters manufacturers with a larger semiconductor area - larger chips. Bridgelux doesn't disclose the number of emitters used in its arrays because it sells the products as integrated single light sources.

Getting back to applications, Posselt discussed product requirements and design trends. He said, "The common approach is to gang together a bunch of emitters. For some applications that solution just doesn't work such as in retail lighting where light quality, lux level, and punch are really critical."

SSL is an ideal technology for retail stores, because lights are on constantly. LED efficiency leads to energy savings in such applications while long lifetimes reduce maintenance costs. But according to Posselt, the application requirements are tough to meet. He said, "We're not displacing incandescent sources, we're displacing 35W, 70W, and 100W ceramic metal halide sources that have a lot of punch."

LED street lights

While the RS family has already found success in retail lighting, the company believes that the new models will lead to success in street lights also. Posselt said, "We have a lot of customers developing solutions for street lighting. The challenge there is obviously developing optical solutions around this larger source size to create the required beam patterns."

Street lights that use small emitters utilized total internal reflection (TIR) lenses to form the beam pattern, but such lenses aren't practical with larger sources such as the Bridgelux arrays. See SSL luminaires must deliver reliable beam patterns in outdoor applications for more information on beam patterns.
According to Posselt, the company is working with partners to combine lens and reflector technology to form the required beam patterns but was unwilling to detail when that technology might come to market. But he added, "We believe there are real benefits in terms of the effective use of light, reducing the bill of materials, and reducing system cost." Posselt asserts that the RS family can replace a 70W - 150W HID source with a single packaged array.



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Cree demonstrates 60W-equivalent LED retrofit lamp

Cree demonstrates 60W-equivalent LED retrofit lamp

LED-based A-lamp achieves Energy Star requirements for 60W replacement lamps, but Cree hasn't formalized plans to bring a product to market.

Cree has developed an LED-based retrofit A-lamp that it claims is the first design that can meet Energy Star requirements for 60W-equivalent products. The company is having the performance of the design validated by a third-party testing lab, but has not decided how or when the technology will come to market.

The demonstration lamp outputs more than 800 lm with a color temperature of 2700K, CRI of 90 or better, and power consumption less than 10W. Cree expects third-party testing to validate lumen maintenance to L70 of 25,000 hours. Energy Star specifies 25,000 hours, and Vice President of Corporate Marketing Greg Merritt said, "We want to at least achieve that."

Cree has not provided details on the light-engine design, but Merritt stated that the performance is enabled by Cree's XLamp LEDs, TrueWhite Technology and patented remote-phosphor technology. TrueWhite Technology mixes light from yellow and red LEDS to offer warm white light.

Dual-dome remote phosphor

Cree hasn't previously announced remote phosphor technology. Merritt describes the retrofit bulb as a dual-dome design with the remote phosphor deployed in the inner dome.

The design uses a passive cooling scheme enabled in part by the increasing efficiency of LEDs according to Merritt. In the nearby photo you can see the cooling fins. Merritt said, "It looks more like a traditional bulb" when asked about more radical designs such as Philips' products that leveraged air channels between portions of the lens. Merritt asserts that consumers have voiced a strong preference for replacement lamps that look like traditional bulbs.

Merritt made the point repeatedly that the development of the retrofit lamp was not simply an engineering exercise. He also acknowledged that Cree hasn't decided how to proceed with the product. Merritt said, "We haven't decided if, how, or when we will bring it to market."

Merritt did hint at a strategy saying, "We have a strong track record of making our innovations available to our customers." When asked if that meant customers of Cree LED components, Merritt added, "All of our customers, customers who want to make similar products." That comment implies that the demonstration is essentially a reference design.

Cree CEO Chuck Swoboda made similar comments about Cree's lighting business in the keynote speech he delivered at a recent LED developers' conference presented by Cree and Arrow (see links at the right for full details). Swoboda had indicated that Cree's system business was largely dedicated to system development that can help customers solve problems thereby ramping component sales.

At the launch of the A-Lamp demonstration, Swoboda said, "We are committed to leading the market and showing the industry what's possible with recent innovations in our LED products and technology. We are excited to show the world what it should expect in an LED light bulb and enable our customers' products with these innovations."

Low cost and high performance

Both Swoboda and Merritt emphasized that the A-Lamp design was designed to be cost-effective and to yield quality light. "In the race to commercialize low-cost, energy-efficient LED bulbs, the industry has forgotten that LED lighting is supposed to look as good as the technology it is replacing," said Swoboda. "This is the first no compromise replacement for a 60 watt incandescent bulb."

When asked about the goals of the project, Merritt said, "We wanted to demonstrate that you could do this with a product that was designed for mass production at an attractive market price." When reminded that the product price was still an unknown, Merritt added, "Obviously you have to take me at my word for this because I'm not telling you how much it costs."

Given the specifications of the retrofit lamp, we wondered if the design might be entered in the US . The DOE has temporarily suspended the PAR 38 portion of the competition while the Philips lamp remains the only entry in the A-Lamp competition. According to Merritt, however, the Cree design was optimized for cost. It doesn't produce the 900 lm required for the L-Prize.

The Cree lamp is designed to meet all of the elements of Energy Star for retrofit lamps. That includes the requirement for uniform light distribution below the equator of the bulb according to Merritt. Merritt asserted that no 60W-equivalent SSL product has complied with Energy Star requirements to date.

Cree chose the anniversary of Edison's patent issue date for the A-Lamp as the date to launch the retrofit demonstration. It was 131 years ago that the patent office recognized what became known as the Edison socket.




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