Foshan WBL Lighting Co. Ltd

LEDs (Light Emitting Diodes) are small, solid light bulbs which are extremely energy-efficient. Until recently, LEDs were limited to single-bulb use in applications such as instrument panels, electronics, pen lights and, more recently, strings of indoor and outdoor Christmas lights.
	Recent improvements in manufacture have lowered the cost of LEDs, which has expanded their application. The bulbs are now available in clusters, from 2 to 36 bulbs, and are popular especially for battery powered items such as flashlights and headlamps. LEDs are also available in arrays which fit standard AC and DC receptacles, lamps, recessed and track lights.
	Benefits:
		Long-lasting - LED bulbs last 10 times as long as compact fluorescents, and 133 times longer than typical incandescents. Durable - Since LEDs do not have a filament, they are not damaged under circumstances when a regular incandescent bulb would be broken. Because they are solid, LED bulbs hold up well to jarring and bumping. Cool - these bulbs do not cause heat build-up; LEDs produce 3.4 btu's/hour, compared to 85 for incandescent bulbs. Energy-saving - LEDs use a fraction of the wattage of incandescent bulbs. Batteries will last 10 to 15 times longer than with incandescent bulbs. Also, because these bulbs last for years, energy is saved in maintenance and replacement costs. Many cities in the US are replacing their incandescent traffic lights with LED arrays because the electricity costs can be reduced by 80% or more. Light for remote areas - because of the low power requirement for LEDs, using solar panels becomes more practical and less expensive than running an electric line or using a generator for lighting.
	Limitations:
		Cost - although the cost keeps going down, LEDs are still expensive. A single AC bulb (30 LED), replacing a 25 watt incandescent, may cost about $40. Light Field - LEDs are focused lights, and therefore are best as task specific lighting such as reading lights, desk lamps, night lights, spotlights, security lights, signage lighting, etc. They do not radiate light in 360 degrees as an incandescent does. The light will be bright where you point it towards. New designs in LED bulbs are addressing this problem of directional focus. Diffuser lenses with clustered bulbs are becoming more common on the market which is broadening the applications for LED use in the home.
	LED Colors: Red - red is the traditional color for maintaining night vision. Green - green is now the preferred color for pilots and the military. The green color is also great for retaining night vision, and it doesn’t erase the red markings on maps and charts. Blue - many people like the blue because it is very easy on the eyes. Blue appears to be a good reading light for elderly eyes. Elderly folks report that they can read under the blue light for hours without eyestrain, compared to severe eyestrain in less than 30 minutes with incandescent lighting. White - the most popular of the LED colors. It produces a soft white light, without harsh reflection, glare or shadows. Amber - LED amber bulbs do not attract flying insects, as do ordinary white bulbs. Amber LEDs are used outdoors in areas such as patios and decks where insects flying around lights are a nuisance.
			Although LEDs are expensive, the cost is recouped over time and in battery savings. For the AC bulbs and large cluster arrays, the best value comes from commercial use where maintenance and replacement costs are expensive. Traffic lights, for example, are being switched over to LEDs in many cities. Smaller arrays, such as those in flashlights, headlamps and small task lights are great for specialty and outdoor use. New clustered arrays with various lenses are now available for more residential applications.

A Light Emitting Diode (LED) is a semiconductor device which converts electricity into light. LED lighting has been around since the 1960s, but is just now beginning to appear in the residential market for space lighting. At first white LEDs were only possible by "rainbow" groups of three LEDs -- red, green, and blue -- by controlling the current to each to yield an overall white light. This changed in 1993 when Nichia created a blue indium gallium chip with a phosphor coating that 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 inch in diameter and uses about ten milliamps to operate at about a tenth of a watt. LEDs are small in size, but can be grouped together for higher intensity applications. LED fixtures require a driver which is analogous to the ballast in fluorescent fixtures. The drivers are typically built into the fixture (like fluorescent ballasts) or they are a plug transformer for portable (plug-in) fixtures. The plug-in transformers allow the fixture to run on standard 120 volt alternating current (AC), with a modest (about 15 to 20 percent) power loss.

The efficacy of a typical residential application LED is approximately 20 lumens per watt (LPW), though efficacies of up to 100 LPW have been created in laboratory settings. Incandescent bulbs have an efficacy of about 15 LPW and ENERGY STAR qualified compact fluorescents are about 60 LPW, depending on the wattage and lamp type. Some manufacturers claim efficacies much higher than 20 LPW; make sure to examine system efficacy, which accounts for the power use of all components. In December 2006, the U.S. Department of Energy studied the efficacy of four luminaries. All four fell short of the manufacturers’ claims; the study implies that manufacturers are relying on measurements of how much light an isolated LED produces, rather than how much light an LED luminaire actually delivers.

LEDs are better at placing light in a single direction than incandescent or fluorescent bulbs. Because of their directional output, they have unique design features that can be exploited by clever designs. 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 also available. Some manufacturers consider applications such as gardens, walkways, and decorative fixtures outside garage doors to be the most cost-efficient.

LED lights are more rugged and damage-resistant than compact fluorescents and incandescent bulbs. LED lights don't flicker. They are very heat sensitive; excessive heat or inappropriate applications dramatically reduce both light output and lifetime. Uses include:

Task and reading lamps
Linear strip lighting (under kitchen cabinets)
Recessed lighting/ceiling cans
Porch/outdoor/landscaping lighting
Art lighting
Night lights
Stair and walkway lighting
Pendants and overhead
Retrofit bulbs for lamps

Definitions and Terms

Term	Definition	Units	How to interpret
Color Temperature	Color of light	Kelvin (K)	Sunlight at sunrise is 1800K 100W Incandescent light bulb is 2850K Overcast Sky is 6500K
Color Rendering Index (CRI)	Light’s effect on color	Scale of 0 to 100 with sunlight at 100	The higher the number, the more “true” the color will look in that light
Brightness	The intensity of the light.	Lumens	The higher the lumens, the brighter the light
Power	Amount of electrical energy consumed	Watts	Lower the watts, the lower the energy consumed
Efficacy	The efficiency of the bulb to convert electricity into light	Lumens per Watt	More efficient bulbs provide more light using less energy

PATH Attributes


	Individual LEDs are considerably more efficient, however, the lamp or fixture design is reduced by the driver and electronics. In addition, LEDs do not product heat like incandescent bulbs.

	LEDs last considerably longer than incandescent or fluorescent lighting. LEDs don’t typically burn out like traditional lighting, but rather gradually decrease in light output. Their “useful life” is defined by the Alliance for Solid-State Illumination Systems and Technologies (ASSIST) as the time it takes until 70% of initial light output is reached, often 50,000 hours. They are resistant to thermal and vibrational shocks and perform well when subjected to frequent on-off cycling.

Ease of Implementation

No additional tools or training are required for installation of LED fixtures.

Initial Cost

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. Currently, there is a limited number of LED fixture manufactures, but this is changing. Retrofit bulbs range from $25 to $60 for night lights and small lamps.

Operational Cost

The cost savings of LEDs can be found in smaller wattage lamps or for applications that take advantage of their longevity, such as difficult to reach places. They are also advantageous for dimmable fixtures, since dimmable fluorescents are expensive.

U.S.Code Acceptance

As with any electrical device, LED fixtures must be listed for use such as with a testing laboratory label. LEDs are not specifically referenced in building codes.

Field Evaluations

Asdal Builders: Henderson, NV

Installation

The small size of LED lights encourages a variety of design options. White LED lamps are available with Edison (screw-in type) bases to retrofit existing fixtures. There are LED strips that can be used under cabinets. In addition, outdoor landscaping fixtures are available.

Warranty

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

Benefits/Costs

LED lamps have many advantages over traditional lighting methods. These include:

Low energy consumption – retrofit bulbs range from 0.83 to 7.3 Watts
Long service life – LED bulbs can last up to 50,000 hours
Durable – LED bulbs are resistant to thermal and vibrational shocks and turn on instantly from -40C° to 185C°, making them ideal for applications subject to frequent on-off cycling, such as garages and basements
Directional distribution of light – good for interior task lighting
No infrared or ultraviolet radiation – excellent for outdoor use because UV light attracts bugs
Safety and environmentally conscious – LEDs contain no mercury and remain cool to the touch
Fully dimmable – LEDs do not change their color tint when dimmed unlike incandescent lamps that turn yellow
No frequency interference – no ballast to interfere with radio and television signals
Range of color – LEDs can be manufactured produce all colors of the spectrum without filters, they can also product white light in a variety of color temperatures

There are some current disadvantages to LED lighting:

LEDs are currently more expensive than more conventional lighting technologies, and may be hard to locate
LED are very heat sensitive. Excessive heat or inappropriate applications dramatically reduces both light output and lifespan
LEDs typically cast light in one direction at a narrow angle compared to incandescent or fluorescent lamps so lenses or reflectors are needed in fixtures to broaden the beam (if desired)

Weiwin Mar. 28th 2009