LED light bulbs
LED light bulbs

Solid state lighting currently has two to four times greater efficacy than incandescent bulbs, and by 2011 efficacy is expected to be five to seven times greater than that of incandescents. Since lighting accounts for 22% of residential electricity consumption and 35% of commercial electricity consumption in California, switching to solid state lighting could eliminate 11-19% of California's residential electricity consumption and 17-30% of the state's commercial electricity consumption. That's enough electricity to power between 3.4 and 5.8 million homes every year.

Solid state lighting comes in several forms: light-emitting diodes (LEDs), organic light-emitting diodes (OLEDs), and polymer light-emitting diodes (PLEDs). All produce light by running a small electrical current through a semiconductor that naturally gives off light when exposed to a current.

Traditional incandescent lighting, in contrast, works by heating a tungsten filament until it glows. This process is not very efficient - only 10% of the energy used by an incandescent bulb is converted to visible light.

Solid state lighting is proven and familiar in many applications such as electronics, flashlights, and traffic lights. However, the technology has only recently begun to replace incandescent and compact fluorescent bulbs in more mainstream lighting applications.

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The Marcus Center at Night
Building Exteriors

Because of solid state lighting's flexibility and durability, artists and architects are increasingly using this technology to light building exteriors.

The Marcus Center for the Performing Arts completed its lighting renovation, shown to the right, in April 2008. The renovation showcases the center as a Milwaukee landmark, and is inspired by the smooth color transitions of renowned local artist Georgia O'Keefe.

The colors constantly blend and change, a feature that is enabled by the choice of solid state lighting, which is easy to control with a computer program.

Another advantage of the LED lighting is the ease of maintenance. Paul Gregory, the president of Focus Lighting and the designer of this "Light Art" installation, states that the lighting "will require no maintenance for 15 years." He adds, "that's a dream for a lighting designer."

More and more buildings and art installations are following the Marcus Center's example. The Empire State Building, for example, will soon be adopting LED lighting for its exterior, and the New Year's Eve ball in Times Square is now lit by LEDs.

Street and Parking Lot Lighting

LED parking lot and street lights are a rapidly emerging solid state lighting application. Leading the way, in February 2009 the City of Los Angeles announced a partnership with the Clinton Climate Initiative (CCI) to replace 140,000 street lights with LED fixtures over the next five years.

The new lights will use 40 to 50 percent less electricity than the city's existing street lights, which currently cost the city $15 million per year to operate. Plus, the lights will last two to three times longer than traditional lights, saving on maintenance costs. LED lights are also more desirable for residents - they increase visibility for drivers and pedestrians, provide more aesthetically pleasing light, and provide a greater sense of safety due to more even light distribution, better color, and greater reliability.

The capital cost for the replacement is financed by a seven year loan from CCI, which will be entirely paid for through the new street lights' energy and maintenance savings, while still saving taxpayers $48 million over the loan period. The LED street lights will save the City of Los Angeles $10 million per year thereafter, and will reduce carbon (CO2) emissions by 40,500 tons per year - equivalent to taking 6,700 cars off the road.

Building off of this success, the Clinton Climate Initiative is expanding to work with other cities on similar street lighting projects. With the Next Generation Lighting Industry Alliance projecting that LED lights will reach first-cost parity with traditional high intensity discharge lights by 2015, the savings will only get better.


Photo credit: US Department of Energy

Traffic Lights in California

One early LED success has been in traffic lights. Because LEDs produce red, yellow, and green light directly, no filter is required, so LED traffic signals require only 10% as much energy as incandescents.

Equally important, LED traffic lights can last up to ten years, compared to only two years for incandescents, reducing the need to close down intersections for maintenance. And when they do fail, they do so gradually, so failures are not dangerous and repairs are not urgent. This results in less traffic congestion, reduced maintenance costs, and less strain on a municipality's workforce.

Another critical advantage is that their low power consumption allows LED traffic lights to be run off of backup batteries for two hours or more. In the event of a power outage or natural disaster, this feature helps maintain order as the city works to respond.

In 2002, California established efficacy standards for new or replacement traffic signals that required the use of LEDs. Two years later, these standards were extended to pedestrian traffic signals.

In 2004, with half of vehicular and pedestrian traffic signals replaced, peak electricity demand savings were approximately 60 Megawatts statewide. Once all signals are replaced, the reduction in peak demand will reach 120 Megawatts, enough to power almost 120,000 homes.