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Wikipedia

LED lamp

An LED lamp or LED light bulb is an electric light that produces light using light-emitting diodes (LEDs). LED lamps are significantly more energy-efficient than equivalent incandescent lamps and can be significantly more efficient than most fluorescent lamps. The most efficient commercially available LED lamps have efficiencies of 200 lumens per watt (Lm/W). Commercial LED lamps have a lifespan many times longer than incandescent lamps.

LED light bulb
A 230-volt LED light bulb with an E27 base (10 watts, 806 lumens, 3000 Kelvins)
TypeLED, Light bulb
A 230-volt LED filament light bulb, with an E27 base. The filaments are visible as the eight yellow vertical lines.
An assortment of LED lamps commercially available in 2010: floodlight fixtures (left), reading light (center), household lamps (center right and bottom), and low-power accent light (right) applications
An 80W Chips on board (COB) LED module from an industrial light luminaire, thermally bonded to the heat sink

LED lamps require an electronic LED driver circuit to operate from mains power lines, and losses from this circuit means that the efficiency of the lamp is lower than the efficiency of the LED chips it uses. The driver circuit may require special features to be compatible with lamp dimmers intended for use on incandescent lamps. Generally the current waveform contains some amount of distortion, depending on the luminaires’ technology.

The LED lamp market is projected to grow from $75.8 billion in 2020 and increasing to $160 billion in 2026.

LEDs come to full brightness immediately with no warm-up delay. Frequent switching on and off does not reduce life expectancy as with fluorescent lighting. Light output decreases gradually over the lifetime of the LED (see Efficiency droop section).

Some LED lamps are drop-in replacements for incandescent or fluorescent lamps. LED lamps may use multiple LED packages for improved light dispersal, heat dissipation, and overall cost. The text on retail LED lamp packaging may show the light output in lumens, the power consumption in watts, the color temperature in Kelvin or a color description such as "warm white", "cool white" or "daylight", the operating temperature range, and sometimes the equivalent wattage of an incandescent lamp delivering the same output in lumens.

Contents

Illustration of Haitz's law, showing improvement in light output per LED over time, with a logarithmic scale on the vertical axis

Before the introduction of LED lamps, three types of lamps were used for the bulk of general (white) lighting:

  • Incandescent lights, which produce light with a glowing filament heated by electric current. These are very inefficient, having a luminous efficacy of 10–17 lumens/W, and also have a short lifetime of 1000 hours. They are being phased out of general lighting applications. Incandescent lamps produce a continuous black body spectrum of light similar to sunlight, and so produce high Color rendering index (CRI).
  • Fluorescent lamps, which produce ultraviolet light by a glow discharge between two electrodes in a low pressure tube of mercury vapor, which is converted to visible light by a fluorescent coating on the inside of the tube. These are more efficient than incandescent lights, having a luminous efficacy of around 60 lumens/W, and have a longer lifetime 6,000–15,000 hours, and are widely used for residential and office lighting. However, their mercury content makes them a hazard to the environment, and they have to be disposed of as hazardous waste.
  • Metal-halide lamps, which produce light by an arc between two electrodes in an atmosphere of argon, mercury and other metals, and iodine or bromine. These were the most efficient white electric lights before LEDs, having a luminous efficacy of 75–100 lumens/W and have a relatively long bulb lifetime of 6,000–15,000 hours, but because they require a 5–7 minute warmup period before turning on, are not used for residential lighting, but for commercial and industrial wide area lighting, and outdoor security lights and streetlights. Like fluorescents, they also contain hazardous mercury.

Considered as electric energy converters, all these existing lamps are inefficient, emitting more of their input energy as waste heat than as visible light. Global electric lighting in 1997 consumed 2016 terawatthours of energy. Lighting consumes roughly 12% of electrical energy produced by industrialized countries. The increasing scarcity of energy resources, and the environmental costs of producing energy, particularly the discovery of global warming due to carbon dioxide emitted by the burning of fossil fuels, which are the largest source of energy for electric power generation, created an increased incentive to develop more energy-efficient electric lights.

The first low-powered LEDs were developed in the early 1960s, and only produced light in the low, red frequencies of the spectrum. In 1968, the first commercial LED lamps were introduced: Hewlett-Packard's LED display, which was developed under Howard C. Borden and Gerald P. Pighini, and Monsanto Company's LED indicator lamp. However, early LED lamps were inefficient and could only display deep red colors, making them unsuitable for general lighting and restricting their usage to numeric displays and indicator lights.

The first high-brightness blue LED was demonstrated by Shuji Nakamura of Nichia Corporation in 1994. The existence of blue LEDs and high-efficiency LEDs led to the development of the first 'white LED', which employed a phosphor coating to partially convert the emitted blue light to red and green frequencies, creating a light that appears white. Isamu Akasaki, Hiroshi Amano and Nakamura were later awarded the 2014 Nobel Prize in Physics for the invention of the blue LED.

China further boosted LED research and development in 1995 and demonstrated its first LED Christmas tree in 1998. The new LED technology application then became prevalent at the start of the 21st century by US (Cree) and Japan (Nichia, Panasonic, and Toshiba) and then starting 2004 by Korea and China (Samsung, Kingsun, Solstice, Hoyol, and others.)

In the US, the Energy Independence and Security Act (EISA) of 2007 authorized the Department of Energy (DOE) to establish the Bright Tomorrow Lighting Prize competition, known as the "L Prize", the first government-sponsored technology competition designed to challenge industry to develop replacements for 60 W incandescent lamps and PAR 38 halogen lamps. The EISA legislation established basic requirements and prize amounts for each of the two competition categories, and authorized up to $20 million in cash prizes. The competition also included the possibility for winners to obtain federal purchasing agreements, utility programs, and other incentives. In May 2008, they announced details of the competition and technical requirements for each category. Lighting products meeting the competition requirements could use just 17% of the energy used by most incandescent lamps in use today. That same year the DOE also launched the Energy Star program for solid-state lighting products. The EISA legislation also authorized an additional L Prize program for developing a new "21st Century Lamp".

Philips Lighting ceased research on compact fluorescents in 2008 and began devoting the bulk of its research and development budget to solid-state lighting. On 24 September 2009, Philips Lighting North America became the first to submit lamps in the category to replace the standard 60 W A-19 "Edison screw fixture" light bulb, with a design based on their earlier "AmbientLED" consumer product. On 3 August 2011, DOE awarded the prize in the 60 W replacement category to a Philips LED lamp after 18 months of extensive testing.

Early LED lamps varied greatly in chromaticity from the incandescent lamps they were replacing. A standard was developed, ANSI C78.377-2008, that specified the recommended color ranges for solid-state lighting products using cool to warm white LEDs with various correlated color temperatures. In June 2008, NIST announced the first two standards for solid-state lighting in the United States. These standards detail performance specifications for LED light sources and prescribe test methods for solid-state lighting products.

Also in 2008 in the United States and Canada, the Energy Star program began to label lamps that meet a set of standards for starting time, life expectancy, color, and consistency of performance. The intent of the program is to reduce consumer concerns due to variable quality of products, by providing transparency and standards for the labeling and usability of products available in the market. Energy Star Certified Light Bulbs is a resource for finding and comparing Energy Star qualified lamps. A similar program in the United Kingdom (run by the Energy Saving Trust) was launched to identify lighting products that meet energy conservation and performance guidelines. Ushio released the first LED filament lamp in 2008.Philips released its first LED lamp in 2009, followed by the world's first 60w equivalent LED lamp in 2010, and a 75 watt equivalent version in 2011.

The Illuminating Engineering Society of North America (IESNA) in 2008 published a documentary standard LM-79, which describes the methods for testing solid-state lighting products for their light output (lumens), efficacy (lumens per watt) and chromaticity.

As of 2016[update], in the opinion of Noah Horowitz of the Natural Resources Defense Council, new standards proposed by the United States Department of Energy would likely mean most light bulbs used in the future would be LED.

By 2019 electricity usage in the United States had decreased for at least five straight years, due in part to U.S. electricity consumers replacing incandescent light bulbs with LEDs due to their energy efficiency and high performance.

Examples of early adoption

LEDs as Christmas illumination in Viborg, Denmark

In 2008 Sentry Equipment Corporation in Oconomowoc, Wisconsin, US, was able to light its new factory interior and exterior almost solely with LEDs. Initial cost was three times that of a traditional mix of incandescent and fluorescent lamps, but the extra cost was recovered within two years via electricity savings, and the lamps should not need replacing for 20 years. In 2009 the Manapakkam, Chennai office of the Indian IT company, iGate, spent 3,700,000 (US$80,000) to light 57,000 sq ft (5,300 m2) of office space with LEDs. The firm expected the new lighting to pay for itself within 5 years.

In 2009 the exceptionally large Christmas tree standing in front of the Turku Cathedral in Finland was hung with 710 LED lamps, each using 2 watts. It has been calculated that these LED lamps paid for themselves in three and a half years, even though the lights run for only 48 days per year.

In 2009 a new highway (A29) was inaugurated in Aveiro, Portugal; it included the first European public LED-based lighting highway.

By 2010 mass installations of LED lighting for commercial and public uses were becoming common. LED lamps were used for a number of demonstration projects for outdoor lighting and LED street lights. The United States Department of Energy made several reports available on the results of many pilot projects for municipal outdoor lighting, and many additional streetlight and municipal outdoor lighting projects soon followed.

LED lamps are often made with arrays of surface mount LED modules that replace incandescent or compact fluorescent lamps, mostly replacing incandescent lamps rated from 5 to 200 watts.

A significant difference from other light sources is that the light is more directional, i.e., emitted as a narrower beam.

White light LEDs

LED lamp used in photography

General-purpose lighting requires a white light, emulating a black body at a specified temperature, from "warm white" (like an incandescent bulb) at 2700K, to "daylight" at around 6000K. The first LEDs emitted light in a very narrow band of wavelengths, of a color characteristic of the energy band gap of the semiconductor material used to make the LED. LEDs that emit white light are made using two principal methods: either mixing light from multiple LEDs of various colors, or using a phosphor to convert some of the light to other colors. The light is not the same as a true black body, giving a different appearance to colors than an incandescent bulb. Color rendering quality is specified by the CRI, and as of 2019[update] is about 80 for many LED bulbs, and over 95 for more expensive high-CRI LED lighting (100 is the ideal value).

RGB or trichromatic white LEDs use multiple LED chips emitting red, green, and blue wavelengths. These three colors combine to produce white light. The color rendering index (CRI) is poor, typically 25 – 65, due to the narrow range of wavelengths emitted. Higher CRI values can be obtained using more than three LED colors to cover a greater range of wavelengths.

The second basic method uses LEDs in conjunction with a phosphor to produce complementary colors from a single LED. Some of the light from the LED is absorbed by the molecules of the phosphor, causing them to fluoresce, emitting light of another color via the Stokes shift. The most common method is to combine a blue LED with a yellow phosphor, producing a narrow range of blue wavelengths and a broad band of "yellow" wavelengths actually covering the spectrum from green to red. The CRI value can range from less than 70 to over 90, although a wide range of commercial LEDs of this type have a color rendering index around 82. Following successive increases in efficacy, which has reached 150 lm/W on a production basis as of 2017, this type has surpassed the performance of trichromatic LEDs.

The phosphors used in white light LEDs can give correlated color temperatures in the range of 2,200 K (dimmed incandescent) up to 7,000 K or more.

Color changing LED lighting

Tunable lighting systems employ banks of colored LEDs that can be individually controlled, either using separate banks of each color, or multi-chip LEDs with the colors combined and controlled at the chip level. For example, white LEDs of different color temperatures can be combined to construct an LED bulb that decreases its color temperature when dimmed.

LED drivers

Main article: LED driver
Household LED lamp with its internal LED elements and LED driver circuitry exposed.

LED chips require controlled direct current (DC) electrical power and an appropriate circuit as an LED driver is required to convert the alternating current from the power supply to the regulated voltage direct current used by the LEDs.

LED drivers are essential components of LED lamps to ensure acceptable lifetime and performance of the lamp. A driver can provide features such as dimming and remote control. LED drivers may be in the same lamp enclosure as the diode array, or remotely mounted from the light-emitting diodes. LED drivers may require additional components to meet regulations for acceptable AC line harmonic current.

Thermal management

High temperature of LEDs can cause premature failure and reduced light output. LED lamps tend to run cooler than their predecessors since there is no electric arc or tungsten filament, but they can still cause burns. Thermal management of high-power LEDs is required to keep the junction temperature of the LED device close to ambient temperature, since increased temperature will cause increased current, more heating, more current, and so on until failure. LEDs use much less power for a given light output, but they do produce some heat, and it is concentrated in a very small semiconductor die, which must be cooled. LED lamps typically include heat sinks and cooling fins. Very high power lamps for industrial uses are frequently equipped with cooling fans. Some place the LEDs and all circuitry in a glass bulb just like conventional incandescent bulbs, but with a helium gas filling to conduct heat and thus cool the LEDs. Others place the LEDs on a circuit board with an aluminum backing; the aluminum back is connected thermally to the aluminum base of the lamp using thermal paste, and the base is embedded in a melamine plastic shell.

Efficiency droop

The term "efficiency droop" refers to the decrease in luminous efficacy of LEDs as the electric current increases above tens of milliamps (mA). Instead of increasing current levels, luminance is usually increased by combining multiple LEDs in one lamp. Solving the problem of efficiency droop would mean that household LED lamps would require fewer LEDs, which would significantly reduce costs.

In addition to being less efficient, operating LEDs at higher electric currents produces high temperatures which compromise the lifetime of the LED. Because of this increased heating at higher currents, high-brightness LEDs have an industry standard of operating at only 350 mA, giving a good compromise between light output, efficiency, and longevity.

Early suspicions were that the LED droop was caused by elevated temperatures. Scientists proved the opposite to be true – that, although the life of the LED would be shortened, elevated temperatures actually improved the efficiency of the LED. The mechanism causing efficiency droop was identified in 2007 as Auger recombination, which was taken with mixed reaction. A 2013 study conclusively identified Auger recombination as the cause of efficiency droop.

LED lamps are used for both general and special-purpose lighting. Where colored light is needed, LEDs that inherently emit light of a single color require no energy-absorbing filters. LED lamps are commonly available as drop-in replacements for either bulbs or fixtures, replacing either an entire fixture (such as LED light panels replacing fluorescent troffers or LED spotlight fixtures replacing similar halogen fixtures) or bulbs (such as LED tubes replacing fluorescent tubes inside troffers or LED HID replacement lamps replacing HID bulbs inside HID fixtures) The differences between replacing a fixture and replacing a bulb are that, when a fixture (like a troffer) is replaced with something like an LED panel, the panel must be replaced in its entirety if the LEDs or the driver it contains fail since it is impossible to replace them individually in a practical fashion (although the driver is often separate and so it may be replaced), where as, if only the bulb is replaced with an LED replacement lamp, the lamp can be replaced independently of the fixture should the lamp fail. Some LED replacement lamps require the fixture to be modified such as by electrically removing the fixture's ballast, thus connecting the LED lamp directly to the mains supply; others can work without any modifications to the fixture.

BAPS Shri Swaminarayan Mandir Atlanta Illumination with color mixing LED fixtures
Computer-led LED lighting allows enhancement of unique qualities of paintings in the National Museum in Warsaw.

White-light LED lamps have longer life expectancy and higher efficiency (more light for the same electricity) than most other lighting when used at the proper temperature. LED sources are compact, which gives flexibility in designing lighting fixtures and good control over the distribution of light with small reflectors or lenses. Because of the small size of LEDs, control of the spatial distribution of illumination is extremely flexible, and the light output and spatial distribution of an LED array can be controlled with no efficiency loss.

LEDs using the color-mixing principle can emit a wide range of colors by changing the proportions of light generated in each primary color. This allows full color mixing in lamps with LEDs of different colors. Unlike other lighting technologies, LED emission tends to be directional (or at least Lambertian), which can be either advantageous or disadvantageous, depending on requirements. For applications where non-directional light is required, either a diffuser is used, or multiple individual LED emitters are used to emit in different directions.

Household LED lamp

Disassembled LED-light bulb with driver circuit board and Edison screw

Lamp sizes and bases

LED lamps are made with standard lamp connections and shapes, such as an Edison screw base, an MR16 shape with a bi-pin base, or a GU5.3 (bi-pin cap) or GU10 (bayonet fitting) and are made compatible with the voltage supplied to the sockets. They include driver circuitry to rectify the AC power and convert the voltage to an appropriate value, usually a switched-mode power supply.

As of 2010[update] some LED lamps replaced higher wattage bulbs; for example, one manufacturer claimed a 16-watt LED lamp was as bright as a 150 W halogen lamp. A standard general-purpose incandescent bulb emits light at an efficiency of about 14 to 17 lumens/W depending on its size and voltage. According to the European Union standard, an energy-efficient lamp that claims to be the equivalent of a 60 W tungsten lamp must have a minimum light output of 806 lumens.

A selection of consumer LED bulbs available in 2012 as drop-in replacements for incandescent bulbs in screw-type sockets

Some models of LED lamps are compatible with dimmers as used for incandescent lamps (although dimmers for incandescent lighting are not suitable for LEDs). LED lamps often have directional light characteristics. These lamps are more power-efficient than compact fluorescent lamps[better source needed] and offer lifespans of 30,000 or more hours, reduced if operated at a higher temperature than specified. Incandescent lamps have a typical life of 1,000 hours, and compact fluorescents about 8,000 hours. The lamps maintain output light intensity well over their lifetimes. Energy Star specifications require the lamps to typically drop less than 10% after 6,000 or more hours of operation, and in the worst case not more than 15%. LED lamps are available with a variety of color properties. The purchase price is higher than most other lamps – although dropping – but the higher efficiency usually makes total cost of ownership (purchase price plus cost of electricity and changing bulbs) lower.

High-power LED "corn cob" light bulb

Several companies offer LED lamps for general lighting purposes. The technology is improving rapidly and new energy-efficient consumer LED lamps are available.

As of 2016[update], in the United States, LED lamps are close to being adopted as the mainstream light source because of the falling prices and because incandescent lamps are being phased out. In the U.S. the Energy Independence and Security Act of 2007 effectively bans the manufacturing and importing of most current incandescent lamps. LED lamps have decreased substantially in price, and many varieties are sold with subsidized prices from local utilities. However, in September 2019 the Trump administration rolled back requirements for new, energy-efficient light bulbs.

A 17 W tube of LEDs which has the same intensity as a 45 W fluorescent tube

LED tube lamps

Main article: LED tube

LED tube lights are designed to physically fit in fixtures intended for fluorescent tubes. Some LED tubular lamps are intended to be a drop-in replacement into existing fixtures if appropriate ballast is used. Others require rewiring of the fixtures to remove the ballast. An LED tube lamp generally uses many individual Surface-Mounted LEDs which are directional and require proper orientation during installation as opposed to Fluorescent tube lamps which emit light in all directions around the tube. Most LED tube lights available can be used in place of T5, T8, T10, or T12 tube designations, T8 is D26mm, T10 is D30mm, in lengths of 590 mm (23 in), 1,200 mm (47 in) and 1,500 mm (59 in).

Lighting designed for LEDs

LED-wall lamp

Newer light fittings with long-lived LEDs built-in, or designed for LED lamps, have been coming into use as the need for compatibility with existing fittings diminishes. Such lighting does not require each bulb to contain circuitry to operate from mains voltage.

Plants

Experiments revealed surprising performance and production of vegetables and ornamental plants under LED light sources. Many plant species have been assessed in greenhouse trials to make sure that the quality of biomass and biochemical ingredients of such plants is at least comparable with those grown in field conditions. Plant performance of mint, basil, lentil, lettuce, cabbage, parsley and carrot was measured by assessing both the health and vigor of the plants and the success of the LEDs in promoting growth. Also noticed was profuse flowering of select ornamentals including primula, marigold and stock.

Light emitting diodes (LEDs) offer efficient electric lighting in desired wavelengths (red + blue) which support greenhouse production in minimum time and with high quality and quantity. As LEDs are cool, plants can be placed very close to light sources without overheating or scorching, requiring much less space for intense cultivation than with hot-running lighting.

Specialty

LED Flashlight replacement bulb (left), with tungsten equivalent (right)
Variable color temperature LED array in a floodlight

White LED lamps have achieved market dominance in applications where high efficiency is important at low power levels. Some of these applications include flashlights, solar-powered garden or walkway lights, and bicycle lights. Colored LED lamps are now commercially used for traffic signal lamps, where the ability to emit bright light of the required color is essential, and in strings of holiday lights. LED automotive lamps are widely used for their long life and small size. Multiple LEDs are used in applications where more light output than available from a single LED is required.

Outdoor LED lighting

LED floodlights

By about 2010 LED technology came to dominate the outdoor lighting industry; earlier LEDs were not bright enough for outdoor lighting. A study completed in 2014 concluded that color temperature and accuracy of LED lights was easily recognized by consumers, with preference towards LEDs at natural color temperatures. LEDs are now able to match the brightness and warmer color temperature that consumers desire from their outdoor lighting system.

LEDs are increasingly used for street lighting in place of mercury and sodium lamps due to their lower running and lamp replacement costs. However, there have been concerns that the use of LED street lighting with predominantly blue light can cause eye damage, and that some LEDs switch on and off at twice mains frequency, causing malaise in some people, and possibly being misleading with rotating machinery due to stroboscopic effects. These concerns can be addressed by use of appropriate lighting, rather than simple concern with cost.

See luminous efficacy for an efficiency chart comparing various technologies.

Comparison table

Cost comparison for 60 watt incandescent equivalent light bulb (U.S. residential electricity prices)
LED (EcoSmart clear) LED(V-TAC) LED (Philips) LED (Cree) CFL Halogen Incan­descent
Purchase price $3.29 $1.79 $2.03 $3.50 $0.99 $1.17 $0.41
Watts 6.5 9 8.5 9.5 14 43 60
lumens (mean) 800 806 800 815 775 750 860
lumens/watt 123.1 89.6 94.1 85.8 55.4 17.4 14.3
Color temperature kelvin 2700 2700 2700 2700 2700 2920 2700
CRI 80 80+ 80 85 82 100 100
Lifespan (hours) 15,000 20,000 10,000 25,000 10,000 1,000 1,000
Lamp lifetime in years@ 6 hours/day 6.8 9.1 4.6 11.4 4.6 0.46 0.46
Energy cost over 20 years@ 12.5 cents/kWh $36 $49 $47 $52 $77 $235 $329
Cost of replacements of the bulbs over 20years $10 $5 $10 $7 $3 $51 $18
Total cost over 20years $45 $55 $57 $59 $80 $287 $347
Total cost per 860lumens $49 $58 $61 $62 $88 $329 $347
Comparison based on 6 hours use per day (43,800 hours over 20 yrs)

In keeping with the long life claimed for LED lamps, long warranties are offered. However, currently there are no standardized testing procedures set by the Department of Energy in the United States to prove these assertions by each manufacturer. A typical domestic LED lamp is stated to have an "average life" of 15,000 hours (15 years at 3 hours/day), and to support 50,000 switch cycles.

Incandescent and halogen lamps naturally have a power factor of 1, but Compact fluorescent and LED lamps use input rectifiers and this causes lower power factors. Low power factors can result in surcharges for commercial energy users; CFL and LED lamps are available with driver circuits to provide any desired power factor, or site-wide power factor correction can be performed. EU standards requires a power factor better than 0.4 for lamp powers between 2 and 5 watts, better than 0.5 for lamp powers between 5 and 25 watts and above 0.9 for higher power lamps.

Energy Star qualification

Energy Star is an international standard for energy efficient consumer products. Devices carrying the Energy Star service mark generally use 20–30% less energy than required by US standards.

Energy Star LED qualifications:

  • Reduces energy costs – uses at least 75% less energy than incandescent lighting, saving on operating expenses.
  • Reduces maintenance costs – lasts 35 to 50 times longer than incandescent lighting and about 2 to 5 times longer than fluorescent lighting. No lamp-replacements, no ladders, no ongoing disposal program.
  • Reduces cooling costs – LEDs produce very little heat.
  • Is guaranteed – comes with a minimum three-year warranty – far beyond the industry standard.
  • Offers convenient features – available with dimming on some indoor models and automatic daylight shut-off and motion sensors on some outdoor models.
  • Is durable – won't break like a glass bulb.

To qualify for Energy Star certification, LED lighting products must pass a variety of tests to prove that the products will display the following characteristics:

  • Brightness is equal to or greater than existing lighting technologies (incandescent or fluorescent) and light is well distributed over the area lit by the fixture.
  • Light output remains constant over time, only decreasing towards the end of the rated lifetime (at least 35,000 hours or 12 annums based on use of 8 hours per day).
  • Excellent color quality. The shade of white light appears clear and consistent over time.
  • Efficiency is as good as or better than fluorescent lighting.
  • Light comes on instantly when turned on.
  • No flicker when dimmed.
  • No off-state power draw. The fixture does not use power when it is turned off, with the exception of external controls, whose power should not exceed 0.5 watts in the off state.
  • Power factor of at least 0.7 for all lamps of 5W or greater.

Many will not work with existing dimmer switches designed for higher power incandescent lamps. The LED lights must be explicitly dimmable and compatible with the brand of dimmer switch. Otherwise it will cause a flicker or glow within the lights.

Color rendering is not identical to incandescent lamps which emit close to perfect black-body radiation as that from the sun and for what eyes have evolved. A measurement unit called CRI is used to express how the light source's ability to render the eight color sample chips compare to a reference on a scale from 0 to 100. LEDs with CRI below 75 are not recommended for use in indoor lighting.

LED lamps may flicker. The effect can be seen on a slow motion video of such a lamp. The extent of flicker is based on the quality of the DC power supply built into the lamp structure, usually located in the lamp base. Longer exposures to flickering light contribute to headaches and eye strain.

LED life span as a function of lumen maintenance drops at higher temperatures, which limits the power that can be used in lamps that physically replace existing filament and compact fluorescent types. Thermal management of high-power LEDs is a significant factor in design of solid state lighting equipment. LED lamps are sensitive to excessive heat, like most solid state electronic components. Also, the presence of incompatible volatile organic compounds can impair the performance and reduce lifetime.

The long life of LEDs, expected to be about 50 times that of the most common incandescent lamps and significantly longer than fluorescent types, is advantageous for users but will affect manufacturers as it reduces the market for replacements in the distant future.

The human circadian rhythm can be affected by light sources. The effective color temperature of daylight is ~5,700K (bluish white) while tungsten lamps are ~2,700K (yellow). People who have circadian rhythm sleep disorders are sometimes treated with light therapy (exposure to intense bluish white light during the day) and dark therapy (wearing amber-tinted goggles at night to reduce bluish light).

Some organizations recommend that people should not use bluish white lamps at night. The American Medical Association argues against using bluish white LEDs for municipal street lighting.

Research suggests that the shift to LED street lighting attracts 48% more flying insects than HPS lamps, which could cause direct ecological impacts as well as indirect impacts such as attracting more gypsy moths to port areas.

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LED lamp
LED lamp Language Watch Edit 160 160 Redirected from SMD LED module An LED lamp or LED light bulb is an electric light that produces light using light emitting diodes LEDs LED lamps are significantly more energy efficient than equivalent incandescent lamps and can be significantly more efficient than most fluorescent lamps 1 2 3 The most efficient commercially available LED lamps have efficiencies of 200 lumens per watt Lm W 4 5 6 Commercial LED lamps have a lifespan many times longer than incandescent lamps LED light bulbA 230 volt LED light bulb with an E27 base 10 watts 806 lumens 3000 Kelvins TypeLED Light bulbA 230 volt LED filament light bulb with an E27 base The filaments are visible as the eight yellow vertical lines An assortment of LED lamps commercially available in 2010 floodlight fixtures left reading light center household lamps center right and bottom and low power accent light right applications An 80W Chips on board COB LED module from an industrial light luminaire thermally bonded to the heat sink LED lamps require an electronic LED driver circuit to operate from mains power lines and losses from this circuit means that the efficiency of the lamp is lower than the efficiency of the LED chips it uses The driver circuit may require special features to be compatible with lamp dimmers intended for use on incandescent lamps Generally the current waveform contains some amount of distortion depending on the luminaires technology 7 The LED lamp market is projected to grow from 75 8 billion in 2020 and increasing to 160 billion in 2026 8 LEDs come to full brightness immediately with no warm up delay Frequent switching on and off does not reduce life expectancy as with fluorescent lighting 9 Light output decreases gradually over the lifetime of the LED see Efficiency droop section Some LED lamps are drop in replacements for incandescent or fluorescent lamps LED lamps may use multiple LED packages for improved light dispersal heat dissipation and overall cost The text on retail LED lamp packaging may show the light output in lumens the power consumption in watts the color temperature in Kelvin or a color description such as warm white cool white or daylight the operating temperature range and sometimes the equivalent wattage of an incandescent lamp delivering the same output in lumens Contents 1 History 1 1 Examples of early adoption 2 Technology overview 2 1 White light LEDs 2 2 Color changing LED lighting 2 3 LED drivers 2 4 Thermal management 2 5 Efficiency droop 3 Application 3 1 Household LED lamp 3 1 1 Lamp sizes and bases 3 1 2 LED tube lamps 3 1 3 Lighting designed for LEDs 3 2 Plants 3 3 Specialty 3 3 1 Outdoor LED lighting 4 Comparison to other lighting technologies 4 1 Comparison table 4 2 Energy Star qualification 5 Limitations 6 See also 7 References 8 Further reading 9 External linksHistory EditSee also Light emitting diode History Illustration of Haitz s law showing improvement in light output per LED over time with a logarithmic scale on the vertical axis Before the introduction of LED lamps three types of lamps were used for the bulk of general white lighting Incandescent lights which produce light with a glowing filament heated by electric current These are very inefficient having a luminous efficacy of 10 17 lumens W and also have a short lifetime of 1000 hours They are being phased out of general lighting applications Incandescent lamps produce a continuous black body spectrum of light similar to sunlight and so produce high Color rendering index CRI Fluorescent lamps which produce ultraviolet light by a glow discharge between two electrodes in a low pressure tube of mercury vapor which is converted to visible light by a fluorescent coating on the inside of the tube These are more efficient than incandescent lights having a luminous efficacy of around 60 lumens W and have a longer lifetime 6 000 15 000 hours and are widely used for residential and office lighting However their mercury content makes them a hazard to the environment and they have to be disposed of as hazardous waste Metal halide lamps which produce light by an arc between two electrodes in an atmosphere of argon mercury and other metals and iodine or bromine These were the most efficient white electric lights before LEDs having a luminous efficacy of 75 100 lumens W and have a relatively long bulb lifetime of 6 000 15 000 hours but because they require a 5 7 minute warmup period before turning on are not used for residential lighting but for commercial and industrial wide area lighting and outdoor security lights and streetlights Like fluorescents they also contain hazardous mercury Considered as electric energy converters all these existing lamps are inefficient emitting more of their input energy as waste heat than as visible light Global electric lighting in 1997 consumed 2016 terawatthours of energy Lighting consumes roughly 12 of electrical energy produced by industrialized countries The increasing scarcity of energy resources and the environmental costs of producing energy particularly the discovery of global warming due to carbon dioxide emitted by the burning of fossil fuels which are the largest source of energy for electric power generation created an increased incentive to develop more energy efficient electric lights The first low powered LEDs were developed in the early 1960s and only produced light in the low red frequencies of the spectrum In 1968 the first commercial LED lamps were introduced Hewlett Packard s LED display 10 which was developed under Howard C Borden and Gerald P Pighini and Monsanto Company s LED indicator lamp 10 However early LED lamps were inefficient and could only display deep red colors making them unsuitable for general lighting and restricting their usage to numeric displays and indicator lights 10 The first high brightness blue LED was demonstrated by Shuji Nakamura of Nichia Corporation in 1994 11 The existence of blue LEDs and high efficiency LEDs led to the development of the first white LED which employed a phosphor coating to partially convert the emitted blue light to red and green frequencies creating a light that appears white 12 Isamu Akasaki Hiroshi Amano and Nakamura were later awarded the 2014 Nobel Prize in Physics for the invention of the blue LED 13 China further boosted LED research and development in 1995 and demonstrated its first LED Christmas tree in 1998 The new LED technology application then became prevalent at the start of the 21st century by US Cree and Japan Nichia Panasonic and Toshiba and then starting 2004 by Korea and China Samsung Kingsun Solstice Hoyol and others 14 In the US the Energy Independence and Security Act EISA of 2007 authorized the Department of Energy DOE to establish the Bright Tomorrow Lighting Prize competition known as the L Prize 15 the first government sponsored technology competition designed to challenge industry to develop replacements for 60 W incandescent lamps and PAR 38 halogen lamps The EISA legislation established basic requirements and prize amounts for each of the two competition categories and authorized up to 20 million in cash prizes 16 The competition also included the possibility for winners to obtain federal purchasing agreements utility programs and other incentives In May 2008 they announced details of the competition and technical requirements for each category Lighting products meeting the competition requirements could use just 17 of the energy used by most incandescent lamps in use today That same year the DOE also launched the Energy Star program for solid state lighting products The EISA legislation also authorized an additional L Prize program for developing a new 21st Century Lamp Philips Lighting ceased research on compact fluorescents in 2008 and began devoting the bulk of its research and development budget to solid state lighting 17 On 24 September 2009 Philips Lighting North America became the first to submit lamps in the category to replace the standard 60 W A 19 Edison screw fixture light bulb 18 with a design based on their earlier AmbientLED consumer product On 3 August 2011 DOE awarded the prize in the 60 W replacement category to a Philips LED lamp after 18 months of extensive testing 19 Early LED lamps varied greatly in chromaticity from the incandescent lamps they were replacing A standard was developed ANSI C78 377 2008 that specified the recommended color ranges for solid state lighting products using cool to warm white LEDs with various correlated color temperatures 20 In June 2008 NIST announced the first two standards for solid state lighting in the United States These standards detail performance specifications for LED light sources and prescribe test methods for solid state lighting products Also in 2008 in the United States and Canada the Energy Star program began to label lamps that meet a set of standards for starting time life expectancy color and consistency of performance The intent of the program is to reduce consumer concerns due to variable quality of products by providing transparency and standards for the labeling and usability of products available in the market 21 Energy Star Certified Light Bulbs is a resource for finding and comparing Energy Star qualified lamps A similar program in the United Kingdom run by the Energy Saving Trust was launched to identify lighting products that meet energy conservation and performance guidelines 22 Ushio released the first LED filament lamp in 2008 23 Philips released its first LED lamp in 2009 24 followed by the world s first 60w equivalent LED lamp in 2010 25 26 27 28 and a 75 watt equivalent version in 2011 29 The Illuminating Engineering Society of North America IESNA in 2008 published a documentary standard LM 79 which describes the methods for testing solid state lighting products for their light output lumens efficacy lumens per watt and chromaticity As of 2016 update in the opinion of Noah Horowitz of the Natural Resources Defense Council new standards proposed by the United States Department of Energy would likely mean most light bulbs used in the future would be LED 30 By 2019 electricity usage in the United States had decreased for at least five straight years due in part to U S electricity consumers replacing incandescent light bulbs with LEDs due to their energy efficiency and high performance 31 Examples of early adoption Edit LEDs as Christmas illumination in Viborg Denmark In 2008 Sentry Equipment Corporation in Oconomowoc Wisconsin US was able to light its new factory interior and exterior almost solely with LEDs Initial cost was three times that of a traditional mix of incandescent and fluorescent lamps but the extra cost was recovered within two years via electricity savings and the lamps should not need replacing for 20 years 17 In 2009 the Manapakkam Chennai office of the Indian IT company iGate spent 3 700 000 US 80 000 to light 57 000 sq ft 5 300 m2 of office space with LEDs The firm expected the new lighting to pay for itself within 5 years 32 In 2009 the exceptionally large Christmas tree standing in front of the Turku Cathedral in Finland was hung with 710 LED lamps each using 2 watts It has been calculated that these LED lamps paid for themselves in three and a half years even though the lights run for only 48 days per year 33 In 2009 a new highway A29 was inaugurated in Aveiro Portugal it included the first European public LED based lighting highway 34 By 2010 mass installations of LED lighting for commercial and public uses were becoming common LED lamps were used for a number of demonstration projects for outdoor lighting and LED street lights The United States Department of Energy made several reports available on the results of many pilot projects for municipal outdoor lighting 35 and many additional streetlight and municipal outdoor lighting projects soon followed 36 Technology overview EditLED lamps are often made with arrays of surface mount LED modules that replace incandescent or compact fluorescent lamps mostly replacing incandescent lamps rated from 5 to 200 watts A significant difference from other light sources is that the light is more directional i e emitted as a narrower beam White light LEDs Edit LED lamp used in photography General purpose lighting requires a white light emulating a black body at a specified temperature from warm white like an incandescent bulb at 2700K to daylight at around 6000K The first LEDs emitted light in a very narrow band of wavelengths of a color characteristic of the energy band gap of the semiconductor material used to make the LED LEDs that emit white light are made using two principal methods either mixing light from multiple LEDs of various colors or using a phosphor to convert some of the light to other colors The light is not the same as a true black body giving a different appearance to colors than an incandescent bulb Color rendering quality is specified by the CRI and as of 2019 update is about 80 for many LED bulbs and over 95 for more expensive high CRI LED lighting 100 is the ideal value RGB or trichromatic white LEDs use multiple LED chips emitting red green and blue wavelengths These three colors combine to produce white light The color rendering index CRI is poor typically 25 65 due to the narrow range of wavelengths emitted 37 Higher CRI values can be obtained using more than three LED colors to cover a greater range of wavelengths The second basic method uses LEDs in conjunction with a phosphor to produce complementary colors from a single LED Some of the light from the LED is absorbed by the molecules of the phosphor causing them to fluoresce emitting light of another color via the Stokes shift The most common method is to combine a blue LED with a yellow phosphor producing a narrow range of blue wavelengths and a broad band of yellow wavelengths actually covering the spectrum from green to red The CRI value can range from less than 70 to over 90 although a wide range of commercial LEDs of this type have a color rendering index around 82 37 Following successive increases in efficacy which has reached 150 lm W on a production basis as of 2017 this type has surpassed the performance of trichromatic LEDs The phosphors used in white light LEDs can give correlated color temperatures in the range of 2 200 K dimmed incandescent up to 7 000 K or more 38 Color changing LED lighting Edit Tunable lighting systems employ banks of colored LEDs that can be individually controlled either using separate banks of each color or multi chip LEDs with the colors combined and controlled at the chip level 39 For example white LEDs of different color temperatures can be combined to construct an LED bulb that decreases its color temperature when dimmed 40 LED drivers Edit Main article LED driver Household LED lamp with its internal LED elements and LED driver circuitry exposed LED chips require controlled direct current DC electrical power and an appropriate circuit as an LED driver is required to convert the alternating current from the power supply to the regulated voltage direct current used by the LEDs LED drivers are essential components of LED lamps to ensure acceptable lifetime and performance of the lamp A driver can provide features such as dimming and remote control LED drivers may be in the same lamp enclosure as the diode array or remotely mounted from the light emitting diodes LED drivers may require additional components to meet regulations for acceptable AC line harmonic current Thermal management Edit High temperature of LEDs can cause premature failure and reduced light output LED lamps tend to run cooler than their predecessors since there is no electric arc or tungsten filament but they can still cause burns Thermal management of high power LEDs is required to keep the junction temperature of the LED device close to ambient temperature since increased temperature will cause increased current more heating more current and so on until failure LEDs use much less power for a given light output but they do produce some heat and it is concentrated in a very small semiconductor die which must be cooled LED lamps typically include heat sinks and cooling fins 24 Very high power lamps for industrial uses are frequently equipped with cooling fans 41 Some place the LEDs and all circuitry in a glass bulb just like conventional incandescent bulbs but with a helium gas filling to conduct heat and thus cool the LEDs 42 Others place the LEDs on a circuit board with an aluminum backing the aluminum back is connected thermally to the aluminum base of the lamp using thermal paste and the base is embedded in a melamine plastic shell Efficiency droop Edit The term efficiency droop refers to the decrease in luminous efficacy of LEDs as the electric current increases above tens of milliamps mA Instead of increasing current levels luminance is usually increased by combining multiple LEDs in one lamp Solving the problem of efficiency droop would mean that household LED lamps would require fewer LEDs which would significantly reduce costs In addition to being less efficient operating LEDs at higher electric currents produces high temperatures which compromise the lifetime of the LED Because of this increased heating at higher currents high brightness LEDs have an industry standard of operating at only 350 mA giving a good compromise between light output efficiency and longevity 43 44 45 46 Early suspicions were that the LED droop was caused by elevated temperatures Scientists proved the opposite to be true that although the life of the LED would be shortened elevated temperatures actually improved the efficiency of the LED 47 The mechanism causing efficiency droop was identified in 2007 as Auger recombination which was taken with mixed reaction 46 A 2013 study conclusively identified Auger recombination as the cause of efficiency droop 48 Application EditLED lamps are used for both general and special purpose lighting Where colored light is needed LEDs that inherently emit light of a single color require no energy absorbing filters LED lamps are commonly available as drop in replacements for either bulbs or fixtures replacing either an entire fixture such as LED light panels replacing fluorescent troffers or LED spotlight fixtures replacing similar halogen fixtures or bulbs such as LED tubes replacing fluorescent tubes inside troffers or LED HID replacement lamps replacing HID bulbs inside HID fixtures The differences between replacing a fixture and replacing a bulb are that when a fixture like a troffer is replaced with something like an LED panel the panel must be replaced in its entirety if the LEDs or the driver it contains fail since it is impossible to replace them individually in a practical fashion although the driver is often separate and so it may be replaced where as if only the bulb is replaced with an LED replacement lamp the lamp can be replaced independently of the fixture should the lamp fail Some LED replacement lamps require the fixture to be modified such as by electrically removing the fixture s ballast thus connecting the LED lamp directly to the mains supply others can work without any modifications to the fixture 49 BAPS Shri Swaminarayan Mandir Atlanta Illumination with color mixing LED fixtures Computer led LED lighting allows enhancement of unique qualities of paintings in the National Museum in Warsaw 50 White light LED lamps have longer life expectancy and higher efficiency more light for the same electricity than most other lighting when used at the proper temperature LED sources are compact which gives flexibility in designing lighting fixtures and good control over the distribution of light with small reflectors or lenses Because of the small size of LEDs control of the spatial distribution of illumination is extremely flexible 51 and the light output and spatial distribution of an LED array can be controlled with no efficiency loss LEDs using the color mixing principle can emit a wide range of colors by changing the proportions of light generated in each primary color This allows full color mixing in lamps with LEDs of different colors 52 Unlike other lighting technologies LED emission tends to be directional or at least Lambertian which can be either advantageous or disadvantageous depending on requirements For applications where non directional light is required either a diffuser is used or multiple individual LED emitters are used to emit in different directions Household LED lamp Edit Disassembled LED light bulb with driver circuit board and Edison screw Lamp sizes and bases Edit LED lamps are made with standard lamp connections and shapes such as an Edison screw base an MR16 shape with a bi pin base or a GU5 3 bi pin cap or GU10 bayonet fitting and are made compatible with the voltage supplied to the sockets They include driver circuitry to rectify the AC power and convert the voltage to an appropriate value usually a switched mode power supply As of 2010 update some LED lamps replaced higher wattage bulbs for example one manufacturer claimed a 16 watt LED lamp was as bright as a 150 W halogen lamp 53 A standard general purpose incandescent bulb emits light at an efficiency of about 14 to 17 lumens W depending on its size and voltage According to the European Union standard an energy efficient lamp that claims to be the equivalent of a 60 W tungsten lamp must have a minimum light output of 806 lumens 54 A selection of consumer LED bulbs available in 2012 as drop in replacements for incandescent bulbs in screw type sockets Some models of LED lamps are compatible with dimmers as used for incandescent lamps 55 although dimmers for incandescent lighting are not suitable for LEDs LED lamps often have directional light characteristics These lamps are more power efficient than compact fluorescent lamps 56 better source needed and offer lifespans of 30 000 or more hours reduced if operated at a higher temperature than specified Incandescent lamps have a typical life of 1 000 hours 57 and compact fluorescents about 8 000 hours 58 The lamps maintain output light intensity well over their lifetimes Energy Star specifications require the lamps to typically drop less than 10 after 6 000 or more hours of operation and in the worst case not more than 15 59 LED lamps are available with a variety of color properties The purchase price is higher than most other lamps although dropping but the higher efficiency usually makes total cost of ownership purchase price plus cost of electricity and changing bulbs lower 18 High power LED corn cob light bulb Several companies offer LED lamps for general lighting purposes The technology is improving rapidly and new energy efficient consumer LED lamps are available 60 As of 2016 update in the United States LED lamps are close to being adopted as the mainstream light source 61 because of the falling prices and because incandescent lamps are being phased out 62 In the U S the Energy Independence and Security Act of 2007 effectively bans the manufacturing and importing of most current incandescent lamps LED lamps have decreased substantially in price and many varieties are sold with subsidized prices from local utilities However in September 2019 the Trump administration rolled back requirements for new energy efficient light bulbs 63 A 17 W tube of LEDs which has the same intensity as a 45 W fluorescent tube LED tube lamps Edit Main article LED tube LED tube lights are designed to physically fit in fixtures intended for fluorescent tubes Some LED tubular lamps are intended to be a drop in replacement into existing fixtures if appropriate ballast is used Others require rewiring of the fixtures to remove the ballast An LED tube lamp generally uses many individual Surface Mounted LEDs which are directional and require proper orientation during installation as opposed to Fluorescent tube lamps which emit light in all directions around the tube Most LED tube lights available can be used in place of T5 T8 T10 or T12 tube designations T8 is D26mm T10 is D30mm in lengths of 590 mm 23 in 1 200 mm 47 in and 1 500 mm 59 in Lighting designed for LEDs Edit LED wall lamp Newer light fittings with long lived LEDs built in or designed for LED lamps have been coming into use as the need for compatibility with existing fittings diminishes Such lighting does not require each bulb to contain circuitry to operate from mains voltage Plants Edit Main article Grow light Light emitting diodes LEDs Experiments revealed surprising performance and production of vegetables and ornamental plants under LED light sources 64 Many plant species have been assessed in greenhouse trials to make sure that the quality of biomass and biochemical ingredients of such plants is at least comparable with those grown in field conditions Plant performance of mint basil lentil lettuce cabbage parsley and carrot was measured by assessing both the health and vigor of the plants and the success of the LEDs in promoting growth Also noticed was profuse flowering of select ornamentals including primula marigold and stock 64 65 Light emitting diodes LEDs offer efficient electric lighting in desired wavelengths red blue which support greenhouse production in minimum time and with high quality and quantity As LEDs are cool plants can be placed very close to light sources without overheating or scorching requiring much less space for intense cultivation than with hot running lighting Specialty Edit LED Flashlight replacement bulb left with tungsten equivalent right Variable color temperature LED array in a floodlight White LED lamps have achieved market dominance in applications where high efficiency is important at low power levels Some of these applications include flashlights solar powered garden or walkway lights and bicycle lights Colored LED lamps are now commercially used for traffic signal lamps where the ability to emit bright light of the required color is essential and in strings of holiday lights LED automotive lamps are widely used for their long life and small size Multiple LEDs are used in applications where more light output than available from a single LED is required Outdoor LED lighting Edit LED floodlights By about 2010 LED technology came to dominate the outdoor lighting industry earlier LEDs were not bright enough for outdoor lighting A study completed in 2014 concluded that color temperature and accuracy of LED lights was easily recognized by consumers with preference towards LEDs at natural color temperatures 66 LEDs are now able to match the brightness and warmer color temperature that consumers desire from their outdoor lighting system LEDs are increasingly used for street lighting in place of mercury and sodium lamps due to their lower running and lamp replacement costs However there have been concerns that the use of LED street lighting with predominantly blue light can cause eye damage and that some LEDs switch on and off at twice mains frequency causing malaise in some people and possibly being misleading with rotating machinery due to stroboscopic effects These concerns can be addressed by use of appropriate lighting rather than simple concern with cost 67 Comparison to other lighting technologies EditSee luminous efficacy for an efficiency chart comparing various technologies Comparison table Edit Cost comparison for 60 watt incandescent equivalent light bulb U S residential electricity prices LED EcoSmart clear 68 LED V TAC 69 LED Philips 70 LED Cree 71 CFL 72 Halogen 73 Incan descent 74 Purchase price 3 29 1 79 2 03 3 50 0 99 1 17 0 41Watts 6 5 9 8 5 9 5 14 43 60lumens mean 800 806 800 815 775 75 750 860lumens watt 123 1 89 6 94 1 85 8 55 4 17 4 14 3Color temperature kelvin 2700 2700 2700 2700 2700 2920 2700CRI 80 80 80 85 82 100 100Lifespan hours 15 000 20 000 10 000 25 000 10 000 1 000 1 000Lamp lifetime in years 6 hours day 6 8 9 1 4 6 11 4 4 6 0 46 0 46Energy cost over 20 years 12 5 cents kWh 36 49 47 52 77 235 329Cost of replacements of the bulbs over 20 years 10 5 10 7 3 51 18Total cost over 20 years 45 55 57 59 80 287 347Total cost per 860 lumens 49 58 61 62 88 329 347Comparison based on 6 hours use per day 43 800 hours over 20 yrs In keeping with the long life claimed for LED lamps long warranties are offered However currently there are no standardized testing procedures set by the Department of Energy in the United States to prove these assertions by each manufacturer 76 A typical domestic LED lamp is stated to have an average life of 15 000 hours 15 years at 3 hours day and to support 50 000 switch cycles 77 Incandescent and halogen lamps naturally have a power factor of 1 but Compact fluorescent and LED lamps use input rectifiers and this causes lower power factors Low power factors can result in surcharges for commercial energy users CFL and LED lamps are available with driver circuits to provide any desired power factor or site wide power factor correction can be performed EU standards requires a power factor better than 0 4 for lamp powers between 2 and 5 watts better than 0 5 for lamp powers between 5 and 25 watts and above 0 9 for higher power lamps 78 79 Energy Star qualification Edit Energy Star is an international standard for energy efficient consumer products 80 81 Devices carrying the Energy Star service mark generally use 20 30 less energy than required by US standards 82 Energy Star LED qualifications 83 Reduces energy costs uses at least 75 less energy than incandescent lighting saving on operating expenses Reduces maintenance costs lasts 35 to 50 times longer than incandescent lighting and about 2 to 5 times longer than fluorescent lighting No lamp replacements no ladders no ongoing disposal program Reduces cooling costs LEDs produce very little heat Is guaranteed comes with a minimum three year warranty far beyond the industry standard Offers convenient features available with dimming on some indoor models and automatic daylight shut off and motion sensors on some outdoor models Is durable won t break like a glass bulb To qualify for Energy Star certification LED lighting products must pass a variety of tests to prove that the products will display the following characteristics Brightness is equal to or greater than existing lighting technologies incandescent or fluorescent and light is well distributed over the area lit by the fixture Light output remains constant over time only decreasing towards the end of the rated lifetime at least 35 000 hours or 12 annums based on use of 8 hours per day Excellent color quality The shade of white light appears clear and consistent over time Efficiency is as good as or better than fluorescent lighting Light comes on instantly when turned on No flicker when dimmed No off state power draw The fixture does not use power when it is turned off with the exception of external controls whose power should not exceed 0 5 watts in the off state Power factor of at least 0 7 for all lamps of 5W or greater Limitations EditMany will not work with existing dimmer switches designed for higher power incandescent lamps 55 The LED lights must be explicitly dimmable and compatible with the brand of dimmer switch Otherwise it will cause a flicker or glow within the lights Color rendering is not identical to incandescent lamps which emit close to perfect black body radiation as that from the sun and for what eyes have evolved A measurement unit called CRI is used to express how the light source s ability to render the eight color sample chips compare to a reference on a scale from 0 to 100 84 LEDs with CRI below 75 are not recommended for use in indoor lighting 85 LED lamps may flicker The effect can be seen on a slow motion video of such a lamp The extent of flicker is based on the quality of the DC power supply built into the lamp structure usually located in the lamp base Longer exposures to flickering light contribute to headaches and eye strain 86 87 88 LED life span as a function of lumen maintenance drops at higher temperatures which limits the power that can be used in lamps that physically replace existing filament and compact fluorescent types Thermal management of high power LEDs is a significant factor in design of solid state lighting equipment LED lamps are sensitive to excessive heat like most solid state electronic components Also the presence of incompatible volatile organic compounds can impair the performance and reduce lifetime 89 The long life of LEDs expected to be about 50 times that of the most common incandescent lamps and significantly longer than fluorescent types is advantageous for users but will affect manufacturers as it reduces the market for replacements in the distant future 17 The human circadian rhythm can be affected by light sources 90 91 The effective color temperature of daylight is 5 700K 92 bluish white while tungsten lamps are 2 700K yellow 93 People who have circadian rhythm sleep disorders are sometimes treated with light therapy exposure to intense bluish white light during the day and dark therapy wearing amber tinted goggles at night to reduce bluish light 94 95 96 Some organizations recommend that people should not use bluish white lamps at night The American Medical Association argues against using bluish white LEDs for municipal street lighting 97 Research suggests that the shift to LED street lighting attracts 48 more flying insects than HPS lamps which could cause direct ecological impacts as well as indirect impacts such as attracting more gypsy moths to port areas 98 See also EditHeadlamp LED LED display List of emerging technologies List of light sources Lux Photometry optics Radiation angle Solar lamp Solid state lighting SpectroscopyReferences Edit How Energy Efficient Light Bulbs Compare with Traditional Incandescents energy gov Retrieved 4 February 2018 CFLs vs LEDs The Better Bulbs greenamerica org Retrieved 31 August 2016 Lightbulb Efficiency Comparison Chart greatercea org 24 March 2015 Retrieved 4 February 2018 Dubai Lamp Philips Lighting Philips ae Retrieved 2 August 2019 Lighting world first Philips breaks 200 lumens per watt barrier PDF Philips com Retrieved 2 August 2019 Philips and Dubai unveil world s most efficient LED bulb newatlas com 6 October 2016 Ciugudeanu Calin Buzdugan Mircea Beu Dorin Campianu Angel Galatanu Catalin Daniel 12 December 2019 Sustainable Lighting Retrofit Versus Dedicated Luminaires Light Versus Power Quality Sustainability 11 24 7125 doi 10 3390 su11247125 ISSN 2071 1050 LED LIGHTING MARKET GROWTH TRENDS COVID 19 IMPACT AND FORECASTS 2021 2026 Mordor Intelligence Retrieved 25 September 2021 Damir B 2012 Longevity of light bulbs and how to make them last longer RobAid Archived from the original on 19 August 2015 Retrieved 10 August 2015 a b c Andrews David L 2015 Photonics Volume 3 Photonics Technology and Instrumentation 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to say goodbye to the lightbulbs you ve loved The Charlotte Observer The Mercury News p 1C Craven McGinty Jo 11 October 2019 Americans Are No Longer Gluttons for Electricity Thank the LED Bulb After increasing 10 fold between 1950 and 2010 average residential consumption dipped The Wall Street Journal For more than five years Americans have been doing something decidedly un American We ve been using less electricity T oday s electronics and appliances are more efficient New homes are tighter and better insulated And most important light emitting diodes or LEDs have replaced traditional incandescent light bulbs Led ing the way Nitya Varadarajan 5 October 2009 Of the top six in Turku led a move HS fi Domestic 19 November 2009 Retrieved 9 January 2012 New highway connecting Lisbon to Oporto includes first European LED based lighting in a highway Aveiro 11 September 2009 U S Department of Energy Solid State Lighting GATEWAY Demonstration Results Archived 9 June 2010 at the Wayback Machine 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PDF on 9 March 2013 Retrieved 1 March 2013 The National Museum in Warsaw is also one of the most modern in Europe The LED system allows to adjust the light to every painting so that its unique qualities are enhanced Moreno Ivan Avendano Alejo Maximino Tzonchev Rumen I 2006 Designing light emitting diode arrays for uniform near field irradiance PDF Applied Optics 45 10 2265 2272 Bibcode 2006ApOpt 45 2265M doi 10 1364 AO 45 002265 PMID 16607994 Moreno Ivan Contreras Ulises 2007 Color distribution from multicolor LED arrays Optics Express 15 6 3607 18 Bibcode 2007OExpr 15 3607M doi 10 1364 OE 15 003607 PMID 19532605 S2CID 35468615 ledlightingsupplier co uk Diese Website steht zum Verkauf Informationen zum Thema ledlightingsupplier ledlightingsupplier co uk Archived from the original on 6 September 2012 Retrieved 26 August 2011 Lonsdale Sarah 7 July 2010 Green property energy efficient bulbs The Daily Telegraph London Retrieved 8 June 2011 a b Dimming LED lamps the dos and don ts luxreview com Elisabeth Rosenthal and Felicity Barringer Green Promise Seen in Switch to LED Lighting The New York Times 29 May 2009 Taub Eric 11 February 2009 How Long Did You Say That Bulb Would Last New York Times Retrieved 9 March 2016 Q amp A How much can I save by replacing incandescent bulbs with CFLs Consumer Reports 29 March 2010 Retrieved 4 February 2018 Integral LED Lamps Criteria Development PDF Taub Eric A 16 May 2010 LED Bulbs for the Home Near the Marketplace The New York Times Wald Matthew L 24 June 2010 An LED That Mimics an Old Standby New York Times Green Blog Flicker On Flicker Off Daniel Gross Slate 5 February 2016 Philips Flattens the Light Bulb Mashable Pete Pachal 16 December 2013 NPR Trump Administration Reverses Standards For Energy Efficient Lightbulbs https www npr org 2019 09 04 757623821 trump administration reverses standards for energy efficient light bulbs a b Sabzalian Mohammad R P Heydarizadeh A Boroomand M Agharokh Mohammad R Sahba M Zahedi and B Schoefs 2014 High performance of vegetables flowers and medicinal plants in a red blue LED incubator for indoor plant production Agronomy for Sustainable Development 34 879 886 IF 3 99 Darko E P Heydarizadeh B Schoefs and Mohammad R Sabzalian 2014 Photosynthesis under artificial light the shift in primary and secondary metabolites Philosophical Transactions of the Royal Society B 369 20130243 IF 6 23 LED advancements drive quality of light gains MAGAZINE LEDs Magazine 22 April 2014 Highways Magazine Public Health England issues LED street lighting warning Highways Magazine UK 3 April 2008 Retrieved 19 January 2019 60 Watt Equivalent A15 Dimmable Filament Classic Glass LED Light Bulb Soft White 3 Pack Home Depot Archived from the original on 5 February 2018 Retrieved 4 February 2018 LED Bulbs LED Bulb 9W E27 A60 Thermoplastic Warm White v tac eu Archived from the original on 10 September 2017 Retrieved 4 February 2018 60W Equivalent Soft White A19 LED Light Bulb 2 Pack Home Depot Archived from the original on 20 October 2017 Retrieved 4 August 2017 Cree 60W Equivalent Soft White 2700K A19 Dimmable LED Light Bulb 4 Pack Home Depot Retrieved 9 October 2017 Solar LEG Lights Green Energy Retrieved 20 January 2014 EcoSmart 60 Watt Equivalent Eco Incandescent A19 Household Light Bulb 4 Pack Home Depot Archived from the original on 5 February 2018 Retrieved 9 October 2017 LED Candle Lamp is capable of replacing up to a 40 watt incandescent bulb LEDfy Retrieved 4 August 2017 Lightbulbs LEDs and CFLs offer more choices and savings PDF ConsumerReports 2011 Archived from the original PDF on 11 August 2013 Retrieved 21 January 2014 Standards Development for Solid State Lighting energy gov Specification of a typical domestic 9 5W LED lamp Philips Archived from the original on 18 November 2018 Retrieved 28 January 2021 PF vs Power in EU ledon at Commission Regulation EU No 1194 2012 PDF EUR Lex 14 December 2012 p 13 Retrieved 5 October 2019 The Clinton Presidency Protecting Our Environment and Public Health The White House Retrieved 4 February 2018 History of Energy Star Archived from the original on 27 March 2012 Retrieved 27 March 2012 Alena Tugend 10 May 2008 If Your Appliances Are Avocado They re Probably not Green New York Times Retrieved 29 June 2008 Energy star products specs Retrieved 4 September 2016 Appendix B Calculating color rendering metrics lrc rpi edu Energy Star Program Requirements for Solid State Lighting Luminaires PDF Retrieved 2 June 2012 Characterizing and Minimizing LED Flicker in Lighting Applications Steven Keeping 2012 Retrieved on 2 February 2018 A Review of the Literature on Light Flicker Ergonomics Biological Attributes Potential Health Effects and Methods in Which Some LED Lighting May Introduce Flicker IEEE Standard P1789 February 2010 Open letter from Alex Baker Lighting Program Manager Energy Star dated 22 March 2010 Cree XLamp LEDs Chemical compatibility URL https www cree com led components media documents XLamp Chemical Comp pdf West Kathleen E Jablonski Michael R Warfield Benjamin Cecil Kate S James Mary Ayers Melissa A Maida James Bowen Charles Sliney David H Rollag Mark D Hanifin John P Brainard George C 1 March 2011 Blue light from light emitting diodes elicits a dose dependent suppression of melatonin in humans Journal of Applied Physiology 110 3 619 626 doi 10 1152 japplphysiol 01413 2009 PMID 21164152 S2CID 23119076 Cajochen Christian Frey Sylvia Anders Doreen Spati Jakub Bues Matthias Pross Achim Mager Ralph Wirz Justice Anna Stefani Oliver 1 May 2011 Evening exposure to a light emitting diodes LED backlit computer screen affects circadian physiology and cognitive performance Journal of Applied Physiology 110 5 1432 1438 doi 10 1152 japplphysiol 00165 2011 PMID 21415172 Williams D R 2004 Sun Fact Sheet NASA Retrieved 4 February 2018 Microscopy Resource Center Olympus Life Science olympus lifescience com Circadian Rhythms nigms nih gov Fahey Christopher D Zee Phyllis C 1 December 2006 Circadian rhythm sleep disorders and phototherapy Psychiatric Clinics of North America 29 4 989 1007 abstract ix doi 10 1016 j psc 2006 09 009 PMID 17118278 Appleman Kenneth Figueiro Mariana G Rea Mark S 1 May 2013 Controlling light dark exposure patterns rather than sleep schedules determines circadian phase Sleep Medicine 14 5 456 461 doi 10 1016 j sleep 2012 12 011 PMC 4304650 PMID 23481485 AMA Adopts Community Guidance to Reduce the Harmful Human and Environmental Effects of High Intensity Street Lighting ama assn org Retrieved 4 February 2018 Pawson S Bader M October 2014 LED lighting increases the ecological impact of light pollution irrespective of color temperature Ecological Applications 24 7 1561 1568 doi 10 1890 14 0468 1 PMID 29210222 Retrieved 6 January 2017 Further reading EditE Fred Schubert 2006 Light Emitting Diodes Cambridge University Press ISBN 978 1 139 45522 0 Krigel A Berdugo M Picard E Levy Boukris R Jaadane I Jonet L Dernigoghossian M Andrieu Soler C Torriglia A Behar Cohen F 2016 Light induced retinal damage using different light sources protocols and rat strains reveals LED phototoxicity PDF Neuroscience 339 296 307 doi 10 1016 j neuroscience 2016 10 015 PMID 27751961 S2CID 1619530 External links Edit Media related to LED lamps at Wikimedia Commons e lumen eu a website from the European Commission about the second generation of energy saving lamps Some cities are taking another look at LED lighting after AMA warning 25 Sep 2016 The Washington Post Retrieved from https en wikipedia org w index php title LED lamp amp oldid 1051977597 Comparison of common SMD surface mounted LED modules, wikipedia, wiki, book,

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