When the ball dropped in New York City's Times Square on New Year's Eve, it was not just signaling the beginning of a new year. It was signaling the beginning of a new era of lighting technology.

On Jan. 1, 2011, an energy-efficient lighting law in California made the traditional 100-watt incandescent light bulb illegal.

A similar federal law, the Energy Independence and Security Act (EISA) of 2007 (Public Law 110-140), goes into effect on Jan. 1, 2012. Its strict energy efficiency requirements for lighting effectively ban the manufacture or import of the "general-service" 100-watt, incandescent bulb with additional efficiency requirements affecting a wide variety of additional lighting.

By Jan. 1, 2013, 75-watt general-service incandescent bulbs will be phased out, followed by 60-watt and 40-watt bulbs by Jan. 1, 2014.

As a result, individual consumers and procurement professionals across the country are examining new lighting technologies such as light emitting diodes (LEDs).

What are LEDs?

LEDs are a semiconductor-based light source more comparable to a computer circuit than to the traditional gas-filled, filament-based incandescent light bulb Thomas Edison perfected back in 1879.

LEDs were prohibitively expensive when invented in 1962. Many of us first experienced LED lights as the high-tech red glow in early calculator displays or as the red indicator light on stereos and other early electronics. LEDs now illuminate cell phones, computer monitors, laptops, televisions and more.

Originally limited to a narrow band of colors, LED technology has improved significantly so that the full spectrum of colors can be produced reliably. The improved color technology, along with steep reductions in manufacturing costs, are making LEDs a practical and affordable specialty and general-purpose lighting solution.

LED quality and price have reached a point where many home improvement centers and other large retailers are routinely stocking LED lights for a variety of uses, including as a replacement for the 100-watt incandescent bulb. Professional purchasers and building managers are taking advantage of volume purchases to further lower costs.

Government purchasing drives innovation

Long before LED light bulbs began appearing on retail shelves, government purchasers were taking advantage of the new technology to reduce operating and maintenance costs for things such as building exit signs and traffic signals. Government purchasers are also switching to LEDs for street lights and general building lighting needs.

Exit signs. LED exit signs can reduce electricity consumption 95 percent versus more energy-demanding incandescent exit signs. With a life expectancy of 50,000 to 200,000 hours (5.5 to 23 years), they can also significantly reduce maintenance costs when compared to incandescent bulbs that must be replaced every six months. According to the U.S. Environmental Protection Agency, each LED exit sign also prevents the release of half a ton of global-warming pollution annually when compared to traditional incandescent technologies.

Traffic signals. LED traffic signal bulbs are now the industry standard for new traffic lights. Converting traffic signals from traditional incandescent bulbs to LEDs can generate significant financial and environmental benefits because they use 93 percent less electricity. According to one study, if every traffic signal in the United States converted from incandescent to LED bulbs, it would save 3 billion kilowatt-hours of electricity. The environmental benefits would be the equivalent of removing more than 350,000 vehicles from the road. The current cost of LED traffic bulbs remains significantly higher than incandescent alternatives, but the energy savings and maintenance costs produce significant return on investment. Incandescent bulbs must be replaced every one or two years while LED bulbs last five to 10 years. According to the Responsible Purchasing Network, the payback time for an LED traffic signal retrofit is two years with a total return on investment of 200 percent.