Light is used outdoors at night to illuminate landscape features, attract shoppers to retail areas, illuminate outdoor sales areas like gas stations and car sales lots, illuminate pedestrian and bicycle pathways in parks and campuses, light athletic fields, and more. Light Emitting Diodes (LEDs) are being developed for many of these applications, from broad areas to narrow paths. Factors that buyers consider when installing outdoor lighting include a good visual environment, control of unwanted light pollution, and energy efficiency, and LED lighting increasingly offers features that address all of these factors. LEDs perform well in cold temperatures, have long lives that reduce maintenance costs, and are expected to offer many control options in the future.

As stated in the U.S. DOE’s Energy Efficiency and Renewable Energy publication linked below,
“Recent advances in LED technology have resulted in a new option for outdoor area lighting, with several potential advantages over metal halide (MH) and high pressure sodium (HPS) sources. Well-designed LED outdoor luminaires can provide the required surface illuminance using less energy and with improved uniformity, compared to HID sources. LED luminaires may also have significantly longer life (50,000 hours or more, compared to 15,000 to 35,000 hours) with better lumen maintenance. Other LED advantages include: they contain no mercury, lead, or other known disposal hazards; and they come on instantly without run-up time or restrike delay. Further, while MH and HPS technologies continue to improve incrementally, LED technology is improving very rapidly in terms of luminous efficacy, color quality, optical design, thermal management, and cost.” http://apps1.eere.energy.gov/buildings/publications/pdfs/ssl/outdoor_area_lighting.pdf

The Solid-State Lighting Gateway Demonstration Program has a complete report about LED Walkway Lighting: Federal Aviation Administration (FAA) Technical Center, available from: http://www.eere.energy.gov/buildings/ssl/gatewaydemos_results.html

Lightsearch (http://www.lightsearch.com) and Facility Zone (http://www.facilityzone.com/) are search engines where numerous lighting products may be located.

For many outdoor lighting applications, high pressure sodium (HPS) is commonly used because of its relatively long lamp life and high lumens per watt, but its poor color rendering make it less desirable in many applications. Metal Halide (MH) is used where white light is desired, but it has slow strike and restrike times and a relatively short life.

As stated in the U.S. DOE’s Energy Efficiency and Renewable Energy publication linked below, “Current LED product quality can vary significantly among manufacturers, so due diligence is required in their proper selection and use. LED performance is highly sensitive to thermal and electrical design weaknesses that can lead to rapid lumen depreciation or premature failure. Further, long-term performance data do not exist given the early stage of the technology's development. Interested users should continue to monitor available information sources on product performance and lifetime, such as CALiPER test results and GATEWAY demonstration program reports.” http://www.eere.energy.gov/buildings/ssl/outdoor_overview.html

Adoption of this technology may be hampered by high first costs and unfamiliar product specifications. The development and adoption of standards for performance is ongoing, and the Lighting Facts label program will help potential buyers understand more about the products. Providing incentives to reduce the cost may also help buyers overcome initial resistance. (Links to these programs are provided in Additional Information below.)

Lack of long-term, in-situ performance data may also be a deterrent, but the Gateway Program of the U.S. DOE Solid State Lighting Program is helping to get more monitored products on the street. In addition, the CALiPER program tests lighting performance and compares test results to manufacturer claims.

Warranties of a few years for a product that is expected to last 20 years or more could be seen by some as a lack of confidence in the product.

Some buyers may also be concerned about finding replacements for products that experience premature failure. Especially for white, it may be difficult to match the color of the original with a replacement. In addition, products are evolving so quickly, that by the time a customer needs a replacement, it is likely that the product is no longer manufactured.

This technology is still new, so some disposal considerations still need to be sorted out. Recycling is likely to be the recommended action. However, not knowing how LED waste will be handled could be a drawback to some, so a take back plan by the manufacturer could help deal with that uncertainty.

Another drawback may be LED light color; the bluer white light may not appeal to those who like warmer sources. Also, “white” light varies from product to product and even the same product in different runs.

HPS, MH, pulse-start MH, ceramic MH, induction, fluorescent, electron stimulated luminescence (ID #104), high efficiency plasma lighting (ID #80), and compact fluorescent lamps are lighting technologies that compete with the proposed technology.