LEDs: A leading light

January 11, 2012

By Drs. Robert & Sonia Vogl
President and Vice President, Illinois Renewable Energy Association

It is estimated the average American family uses about 1,000 kWh of electricity each month. Home lighting consumption is estimated at between 9 percent and 16 percent, and commercial and office lighting can be as high as 24 percent. While estimates vary, they do provide some idea of the importance of lighting in our lives and the opportunities to cut consumption for economic and environmental benefits.

While turning off lights was a common request from parents in American households, its popularity waned in prosperous times but could return with the economic decline. This time, with compact fluorescent bulbs (CFLs), the request should include the modification of “if you plan to leave the room and not return within 15 minutes, please turn off the lights.” A CFL uses a surge of energy when first turned on, which will shorten its life if frequently cycled. With incandescent bulbs disappearing from the marketplace, the 15-minute admonition may prevail. However, LEDs could become the prevailing lighting mode. They can be turned on and off frequently with no impact on bulb life or light quality.

We have all become accustomed to LEDs since they appeared in flashlights. Their use continues to spread as Christmas tree lights, vehicle taillights and headlights, decorative outdoor lighting and traffic control lights.

An engineer friend, Victor Zaderej, informed us that in many areas of China, large steel buildings without windows serve as greenhouses and use LED lighting to stimulate plant growth. Others have informed us of factories, assembly plants and warehouses illuminated by LEDs.

Our demonstration greenhouse is PV powered and lit with LEDs. For the moment, we have the world’s only known installation of an LED grow light system fitted to a metallic power strip that allows bulbs to be shifted to any site desired on it. The new system will hit the market next spring. While of no great significance, it is fun to be able to say we are the only place in the world where light is being provided with this new system.

What is the claim to fame for LEDs? A high-quality LED can last up to 50,000 hours, eliminating the need for frequent bulb replacements, saving both time and money for the user. The disappearing incandescent bulbs only last up to 3,000 hours, while CFLs can last up to 9,000 hours.

In terms of efficient energy use, incandescents only use 5 percent of the supplied electricity to produce light while the remaining energy is dissipated as heat. CFLs have an efficiency of 25 percent while LEDs convert 50 percent of the electricity to light, yet release enough heat to necessitate the use of a heat sink to protect the bulb.

LEDs use direct current, so an electronic device is included in a unit to convert AC power from the grid to DC. Considering the proliferation of DC-powered electronics in homes, at some point it may make sense for buildings to be DC powered to reduce the need for conversion units.

A small percentage of people appear sensitive to a flickering effect from LEDs not visible to the naked eye. According to an article by Brent Polich in Environmental Building News, it results from the 60-hertz cycle characteristic of our AC power. Complaints include eyestrain, headaches and slower reading speed and comprehension.

Since LEDs are electronic devices that include potentially harmful chemicals, they need to be disposed of in the same way as an electronic device.

As costs continue to drop, light quality improves, and applications expand, LEDs will play increased roles in daily lives.

Drs. Robert and Sonia Vogl are founders and officers of the Illinois Renewable Energy Association (IREA) and coordinate the annual Renewable Energy and Sustainable Lifestyle Fair. E-mail sonia@essex1.com.

From the Jan. 11-17, 2012, issue

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