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White LED Lighting - 11/15/2004 - House Systems Electrical

White LED Lighting

LED (light emitting diode) lamps consume less than a quarter of the electricity that fluorescent lighting does, and the lamps last about ten times as long.

LED lighting system.You thought fluorescent was energy-efficient. But LED (light emitting diode) lamps consume less than a quarter of the electricity that fluorescent lighting does, and the lamps last about ten times as long. Until recently, though, the price of an LED lighting system was too high for most residential use. With sales rising and prices steadily decreasing, it's been said that whoever makes the best white LED will open a goldmine.

White LED lighting has been used for years by the RV and boating crowd, running off direct current (DC) battery systems. It then got popular in off-the-grid houses, powered by photovoltaic cells. It used to be that white LED was possible only by "rainbow" groups of three LEDs -- red, green, and blue -- and controlling the current to each to yield an overall white light. Now a blue indium gallium chip with a phosphor coating is used to create the wave shift necessary to emit white light from a single diode. This process is much less expensive for the amount of light generated.

Each diode is about 1/4" and consumes about ten milliamps (a tenth of a watt). Lamps come in various arrangements of diodes on a circuit board. Standard arrays are three, six, 12, or 18 diodes, or custom sizes -- factories can incorporate these into custom-built downlights, sconces and surface-mounted fixtures. With an inexpensive transformer, they run on standard 120 volt alternating current (AC), albeit with a slight (about 15% to 20%) power loss. They are also available as screw-in lamps to replace incandescent. A 1.2 watt white LED light cluster is as bright as a 20-watt incandescent lamp (bright enough to read by).

The lighting quality is comparable to that of cool white compact fluorescent lamps, with color rendering indices near 85. LED lights don't flicker. The light is very directional in small arrays. LED strip lights can be installed under counters, in hallways, and in staircases. Concentrated arrays can be used for room lighting. Waterproof, outdoor fixtures are available, and they operate in temperatures from -20°C to 80°C. Manufacturers consider applications such as gardens, walkways, and decorative fixtures outside garage doors to be the most cost-efficient.


Energy Efficiency LEDs can use up to 90% less energy than an equvalent incandescent bulb. If many LEDs are used in place of other types of bulbs, incredible energy savings can result.
Quality and Durability LEDs last considerably longer than incandescent lighting, ranging from 50,000 to 100,000 hours of use. In addition, they can perform well in cold and can be made fro harsh weather conditions.


Easy

There is a limited number of manufacturers, but this is changing. Some fixtures are subject to backorder until market/production stabilizes.

The biggest limitation to LED for common residential use is the cost of manufacturing due to still-limited production runs. Manufacturers claim production will increase considerably in the near future, further lowering prices.


Greater than comparable products

An 18" strip light, which is the equivalent of a 25-watt incandescent lamp, costs $128. Transformers for AC systems typically cost $6 to $20 depending upon amperage.


Less than comparable products

Standard LED clusters use up to 90% less power than their incandescent equivalent.


12V amber LED strip lights meet code for emergency lighting.


Asdal Builders: Henderson, Nevada


White LED lamps are available with standard screw-in bases to fit incandescent fixtures. They are much smaller than compact fluorescent and even incandescent, because instead of a bulb, there is an array of tiny diodes lining the rim of the base. They also come as strips that can be used under cabinets.


Warranties for LEDs can range from 3 to 5 years, depending on manufacturer.


Imagine never having to change lamps, which consume too little electricity to notice. LED lights work well for rooms with TV or radio because they do not generate radio frequency interference as some compact fluorescent lamps do. They produce little heat, and can operate in hot or cold environments.


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