Exit Signs

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Introduction

Solid-state lighting is the first genuinely new lighting technology in more than a century. The light emitting diode (LED) lighting systems, which reduce electricity consumption by up to 85%, have proven to be very effective in applications where brightness, visibility and long life are important, such as in exit signs and traffic signals. New uses for LEDs include small area lighting, such as task and under-shelf fixtures, decorative lighting, and pathway and step marking. Industry and government are researching solid-state technology for general illumination in residential and commercial settings.

Technology Options

LEDs are highly efficient semiconductor devices. They can emit considerable amounts of light from small inputs of power. For instance, LED traffic signals use between 6 to 25 watts while incandescent bulb signals use between 70 to 150 watts.

Current market-ready or near market-ready uses of LED lighting include:

Commercial Signage: Commercial signage often operates 12 to 24 hours per day, consuming about 2% of the total electricity in the United States. Fluorescent signs currently account for about 48% of this market, with neon signs holding about 41%, and the remainder of the market dominated by incandescent products.

Institutional, Industrial and Commercial Lighting: LED products can have a significant impact on energy use in airport, ports and roadway lighting, where conventional fluorescent- and incandescent-lit signage is heavily used.

Retail Lighting: LEDs offer unprecedented flexibility in colors and configurations to lighting designers in creating displays and “moods” in retail settings.

Key resources pertaining to LED technology:
  • LED Lighting Systems, 2003 (47 pgs.), by John Bullough
  • Information from ENERGY STAR about high efficiency exit signs and traffic signals
  • Information from the Lighting Research Center at Rensselaer Polytechnic Institute on LEDs in transportation applications
  • Specifications on LED traffic signals developed by the California Department of Transportation (Caltrans)

Efficiency Benefits

Well- documented studies have proven the energy savings potential of LEDs:

  • Replacing a red incandescent traffic signal head with a red LED unit cuts energy use by an estimated 82 to 93%. The use of LED traffic signals in cities can save 1 million kilowatt-hours (kWh) of energy and nearly $70,000 a year for every 100 signaled intersections replaced. The payback period is approximately two-and-a-half to three years through energy savings alone.
  • There are 100 million exit signs in the United States containing incandescent lamps that consume a total of 20 billion kWh of electricity per year. LED lighting could save approximately three-quarters of this energy. By purchasing 1,000 exit signs for an initial investment of $30,000, a state government could save a net $455,562 over the products’ lifetime. The new signs would pay for themselves in six months.
  • LEDs can replace neon, offering an 80% electricity efficiency improvement.

The benefits of LED lighting technology go far beyond reducing electricity consumption. Even with a higher initial investment, dollar savings and quality improvements significantly outweigh costs.

LED technology's numerous benefits also include:
  • Long life and reduced maintenance cost
  • High quality light output
  • Increased safety as a result of LED's lower voltage
  • Smaller, flexible light fixtures
  • Increased durability (no filament to break)

Manufacturers

Here is a partial list of major solid-state lighting manufacturers:


DMF Lighting and Liton Lighting are a couple of the manufacturers of ENERGY STAR qualified exit signs in California.

Purchasing Tips

A recent report by Sandia National Laboratories observed that the light output and efficacy of LEDs roughly doubles every 18 to 24 months. This speed of advancement requires that you keep up-to-date on available LED products and specify the latest technology available.

For help selecting traffic signals and exit signs, ENERGY STAR maintains lists of ENERGY STAR qualified models. Products that have the ENERGY STAR label mean that they have been certified to consume less than 5 watts of power per face. Also, retrofit kits for converting existing exit signs to LEDs are now available on the market; installation may take as little as 15 minutes.

LED "light bulbs" (screw-mounted lamps in the shape of incandescent bulbs) are available for beacon and accent lighting, and for a wide variety of retail lighting applications. It should be noted that most lighting designers and energy efficiency program managers are accustomed to comparing the relative efficacy of light sources in terms of lumens per watt (lm/w). This metric assumes that the light source being measured emits light in a fairly broad spatial distribution pattern. When comparing and selecting, bear in mind that LED packages emit light in a relatively narrow cone of distribution, so it is more difficult to determine lumens per watt for LED-based systems.

Emerging Technology

If white-light emitting solid-state lighting devices can replace conventional incandescent bulbs and fluorescent lamps, the United States could cut energy used for lighting by as much as 50%. No other electricity consumer has such a large energy-savings potential. Driven by the potential cost savings, the U.S. government has launched an initiative to try to accelerate time-to-market. The 10-year plan, called the Next Generation Lighting Initiative, is part of the National Energy Bill and proposes to offer researchers funding resources to develop the technology. A few important potential uses for LED technology include:

Displays: Typically, small fluorescent lights have been used to provide backlighting for liquid crystal displays (LCDs) in computer monitors and televisions.

Retail Food and Beverage Displays: LED lighting has the potential to excel in the grocery market, specifically in coolers and freezers. Currently, display lighting accounts for about 15% of all refrigeration energy use in the United States, and is dominated by fluorescent lighting.

White-light emitting technology, such as LEDs, is seen as the lighting source of the future. Technology roadmaps maintained by the U.S. Departments of Energy and Defense, in cooperation with manufacturers, set research and development goals of developing white LEDs bright enough for general illumination applications by 2010. Solid-state lamps using a few LED "filaments" could potentially be capable of replacing less energy-efficient incandescent and halogen reflectors.