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A compact fluorescent lamp (CFL), also called compact fluorescent light, energy-saving light and compact fluorescent tube, is a
fluorescent lamp A fluorescent lamp, or fluorescent tube, is a low-pressure mercury-vapor gas-discharge lamp that uses fluorescence to produce visible light. An electric current in the gas excites mercury vapor, which produces short-wave ultraviolet li ...
designed to replace an
incandescent light bulb An incandescent light bulb, incandescent lamp or incandescent light globe is an electric light with a wire filament heated until it glows. The filament is enclosed in a glass bulb with a vacuum or inert gas to protect the filament from oxida ...
; some types fit into
light fixture A light fixture (US English), light fitting (UK English), or luminaire is an electrical device containing an electric lamp that provides illumination. All light fixtures have a fixture body and one or more lamps. The lamps may be in sockets fo ...
s designed for incandescent bulbs. The lamps use a tube that is curved or folded to fit into the space of an incandescent bulb, and a compact electronic ballast in the base of the lamp. Compared to general-service incandescent lamps giving the same amount of visible light, CFLs use one-fifth to one-third the electric power, and last eight to fifteen times longer. A CFL has a higher purchase price than an incandescent lamp, but can save over five times its purchase price in electricity costs over the lamp's lifetime. Like all fluorescent lamps, CFLs contain toxic mercury, which complicates their disposal. In many countries, governments have banned the disposal of CFLs together with regular garbage. These countries have established special collection systems for CFLs and other hazardous waste. The principle of operation remains the same as in other
fluorescent lighting A fluorescent lamp, or fluorescent tube, is a low-pressure mercury-vapor gas-discharge lamp that uses fluorescence to produce visible light. An electric current in the gas excites mercury vapor, which produces short-wave ultraviolet ligh ...
: electrons that are bound to mercury atoms are excited to states where they will radiate ultraviolet light as they return to a lower energy level; this emitted ultraviolet light is converted into visible light as it strikes the fluorescent coating, and into heat when absorbed by other materials such as glass. CFLs radiate a
spectral power distribution In radiometry, photometry, and color science, a spectral power distribution (SPD) measurement describes the power per unit area per unit wavelength of an illumination ( radiant exitance). More generally, the term ''spectral power distributio ...
that is different from that of incandescent lamps. Improved
phosphor A phosphor is a substance that exhibits the phenomenon of luminescence; it emits light when exposed to some type of radiant energy. The term is used both for fluorescent or phosphorescent substances which glow on exposure to ultraviolet or ...
formulations have improved the perceived color of the light emitted by CFLs, such that some sources rate the best "soft white" CFLs as subjectively similar in color to standard incandescent lamps. White LED lamps compete with CFLs for high-efficiency lighting.Amber Angelle, "Will LED Light Bulbs Best Your CFLs and Incandescents?
''Popular Mechanics'' August 4, 2010
accessed May 30, 2011
General Electric General Electric Company (GE) is an American multinational conglomerate founded in 1892, and incorporated in New York state and headquartered in Boston. The company operated in sectors including healthcare, aviation, power, renewable energ ...
has since stopped production of domestic CFL lamps in the United States in favour of LEDs.


History

The parent to the modern fluorescent lamp was invented in the late 1890s by Peter Cooper Hewitt. The Cooper Hewitt lamps were used for photographic studios and industries. Edmund Germer, Friedrich Meyer, and Hans Spanner patented a high-pressure vapor lamp in 1927. George Inman later teamed with
General Electric General Electric Company (GE) is an American multinational conglomerate founded in 1892, and incorporated in New York state and headquartered in Boston. The company operated in sectors including healthcare, aviation, power, renewable energ ...
to create a practical fluorescent lamp, sold in 1938 and patented in 1941. Circular and U-shaped lamps were devised to reduce the length of fluorescent light fixtures. The first fluorescent light bulb and fixture were displayed to the general public at the
1939 New York World's Fair The 1939–40 New York World's Fair was a world's fair held at Flushing Meadows–Corona Park in Queens, New York, United States. It was the second-most expensive American world's fair of all time, exceeded only by St. Louis's Louisiana Pur ...
. The spiral CFL was invented in 1976 by
Edward E. Hammer Edward E. Hammer (December 27, 1931 – July 16, 2012) was an engineer who was at the forefront of fluorescent lighting research. His technological contributions in incandescent, fluorescent and HID light sources earned him over 35 patents. He re ...
, an engineer with General Electric, in response to the 1973 oil crisis. Although the design met its goals, it would have cost GE about $25 million to build new factories to produce the lamps, and thus the invention was shelved. The design was eventually copied by others. In 1980,
Philips Koninklijke Philips N.V. (), commonly shortened to Philips, is a Dutch multinational conglomerate corporation that was founded in Eindhoven in 1891. Since 1997, it has been mostly headquartered in Amsterdam, though the Benelux headquarters is ...
introduced its model SL*18, which was a screw-in or bayonet mount lamp with integral magnetic ballast. The lamp used a folded T4 tube, stable tri-color phosphors, and a mercury amalgam. Inventor of new phosphors was Louis Vrenken. This was the first successful screw-in replacement for an incandescent lamp, using new rare earth aluminum lattice phosphors to solve the problem of lumen depreciation that would normally occur quickly in such a thin tube; however, it wasn't widely adopted, because of its large size, weight (over half a kilogram), pronounced 50 Hz flicker and 3-minute warm up time. It was based on the SL1000 prototype from 1976. In 1985, Osram started selling its model Dulux EL, which was the first CFL to include an electronic ballast. Volume was an issue in CFL development, since the fluorescent lamps had to fit in the same volume as comparable incandescent lamps. This required the development of new, high-efficacy phosphors that could withstand more power per unit area than the phosphors used in older, larger fluorescent tubes. In 1995, helical CFLs, manufactured in China by Shanghai Xiangshan, became commercially available. They were first proposed by General Electric, who saw difficulties bending glass tubes into spirals using automated machinery. Xiangshan solved this problem by bending the tubes by hand, made possible by the then-low labor costs in China. Since that time, sales steadily increased. The phosphor coating in spiral CFLs is uneven, being thicker at the bottom than at the top, owing to the effect of gravity during the coating process. Although their popularity varied across countries, in China CFLs were the "dominant technology in the residential segment" in 2011. The rise of LED lighting, however, significantly affected CFL sales and production. As a result of decreasing cost and better features, customers increasingly migrated toward LEDs. In India, "nearly 60 per cent of the lighting market in India has been taken over by LEDs" by 2018. LED prices fell well below US$5 for a basic bulb in 2015. In the United States, CFLs were also facing the possibility of proposed regulations for 2017 that would create difficulty qualifying for the Energy Star rating. In early 2016, General Electric announced it would phase out CFL production in the US. File:Old compact fluorescent lamp.JPG, Philips SL*18, an early CFL File:Compact-Fluorescent-Bulb.jpg, A helical integrated CFL, one of the most popular designs in North America since 1995, when a Chinese firm marketed the first successful design.


Pattern

There are two types of CFLs — integrated and non-integrated lamps, where CFL-i denotes an integrated ballast and CFL-ni denotes a non-integrated ballast. Integrated lamps combine the tube and ballast in a single unit. These lamps allow consumers to replace incandescent lamps easily with CFLs. Integrated CFLs work well in many standard incandescent light fixtures, reducing the cost of converting to fluorescent. 3-way lamps and dimmable models with standard bases are available. Non-integrated CFLs have the ballast permanently installed in the luminaire, and usually only the fluorescent tube is changed at its end of life. Since the ballasts are placed in the light fixture, they are larger and last longer compared to the integrated ones, and they don't need to be replaced when the tube reaches its end-of-life. Non-integrated CFL housings can be both more expensive and sophisticated. They have two types of tubes: a bi-pin tube designed for conventional ballast, e.g. with G23 or G24d plug-in base, and a quad-pin tube designed for an electronic ballast or a conventional ballast with an external starter. A bi-pin tube contains an integrated starter, which obviates the need for external heating pins but causes incompatibility with electronic ballasts. Non-integrated CFLs can also be installed to a conventional light fixture using an adapter containing a built-in magnetic ballast. The adapter consists of a regular bulb screw, the ballast itself and a clip for the lamp's connector. CFLs have two main components: a magnetic or electronic ballast and a gas-filled tube (also called bulb or burner). Replacement of magnetic
ballast Ballast is material that is used to provide stability to a vehicle or structure. Ballast, other than cargo, may be placed in a vehicle, often a ship or the gondola of a balloon or airship, to provide stability. A compartment within a boat, ship, ...
s with electronic ballasts has removed most of the flickering and slow starting traditionally associated with fluorescent lighting, and has allowed the development of smaller lamps directly interchangeable with more sizes of incandescent light bulb. Electronic ballasts contain a small circuit board with a bridge rectifier, a filter
capacitor A capacitor is a device that stores electrical energy in an electric field by virtue of accumulating electric charges on two close surfaces insulated from each other. It is a passive electronic component with two terminals. The effect of a ...
and usually two switching
transistor upright=1.4, gate (G), body (B), source (S) and drain (D) terminals. The gate is separated from the body by an insulating layer (pink). A transistor is a semiconductor device used to Electronic amplifier, amplify or electronic switch, switch ...
s, which are often
insulated-gate bipolar transistor An insulated-gate bipolar transistor (IGBT) is a three-terminal power semiconductor device primarily used as an electronic switch, which, as it was developed, came to combine high efficiency and fast switching. It consists of four alternating la ...
s. The incoming AC current is first rectified to DC, then converted to high frequency AC by the transistors, connected as a resonant series DC to AC inverter. The resulting high frequency is applied to the lamp tube. Since the resonant converter tends to stabilize lamp current (and light emitted) over a range of input voltages, standard CFLs respond poorly in dimming applications and will experience a shorter lifespan and sometimes catastrophic failure. Special electronic ballasts (integrated or separate) are required for dimming service. CFL light output is roughly proportional to phosphor surface area, and high output CFLs are often larger than their incandescent equivalents. This means that the CFL may not fit well in existing light fixtures. To fit enough phosphor coated area within the approximate overall dimensions of an incandescent lamp, standard shapes of CFL tube are a helix with one or more turns, multiple parallel tubes, circular arc, or a butterfly. Some CFLs are labeled not to be run base up, since heat will shorten the ballast's life. Such CFLs are unsuitable for use in pendant lamps and especially unsuitable for recessed light fixtures. CFLs designed for use in such fixtures are available. Current recommendations for fully enclosed, unventilated light fixtures (such as those recessed into insulated ceilings), are either to use "reflector CFLs" (R-CFL), cold-cathode CFLs or to replace such fixtures with those designed for CFLs. A CFL will thrive in areas that have good airflow, such as in a table lamp.


Characteristics


Spectrum of light

CFLs emit light from a mix of
phosphor A phosphor is a substance that exhibits the phenomenon of luminescence; it emits light when exposed to some type of radiant energy. The term is used both for fluorescent or phosphorescent substances which glow on exposure to ultraviolet or ...
s, each emitting one band of color with some bands still in the
ultraviolet Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30  PHz) to 400 nm (750  THz), shorter than that of visible light, but longer than X-rays. UV radiati ...
range as can be seen on the light spectrum. Modern phosphor designs balance the emitted light color, energy efficiency, and cost. Every extra phosphor added to the coating mix improves color rendering but decreases efficiency and increases cost. Good quality consumer CFLs use three or four phosphors to achieve a "white" light with a color rendering index (CRI) of about 80, where the maximum 100 represents the appearance of colors under daylight or other sources of
black-body radiation Black-body radiation is the thermal electromagnetic radiation within, or surrounding, a body in thermodynamic equilibrium with its environment, emitted by a black body (an idealized opaque, non-reflective body). It has a specific, continuous sp ...
such as an
incandescent light bulb An incandescent light bulb, incandescent lamp or incandescent light globe is an electric light with a wire filament heated until it glows. The filament is enclosed in a glass bulb with a vacuum or inert gas to protect the filament from oxida ...
(depending on the correlated color temperature).
Color temperature Color temperature is the color of light emitted by an idealized opaque, non-reflective body at a particular temperature measured in kelvins. The color temperature scale is used to categorize the color of light emitted by other light sources ...
can be indicated in
kelvin The kelvin, symbol K, is the primary unit of temperature in the International System of Units (SI), used alongside its prefixed forms and the degree Celsius. It is named after the Belfast-born and University of Glasgow-based engineer and ph ...
s or mireds (1 million divided by the color temperature in kelvins). The color temperature of a light source is the temperature of a
black body A black body or blackbody is an idealized physical object, physical body that absorption (electromagnetic radiation), absorbs all incident electromagnetic radiation, regardless of frequency or angle of incidence (optics), angle of incidence. T ...
that has the same
chromaticity Chromaticity is an objective specification of the quality of a color regardless of its luminance. Chromaticity consists of two independent parameters, often specified as hue (h) and colorfulness (s), where the latter is alternatively called ...
(i.e. color) as the light source. A notional temperature, the correlated color temperature, the temperature of a black body that emits light of a hue that to human color perception most closely matches the light from the lamp, is assigned. The color temperature is characteristic of black-body radiation; practical white light sources approximate the radiation of a black body at a given temperature, but will not have an identical spectrum. In particular, narrow bands of shorter-wavelength radiation are usually present even for lamps of low color temperature ("warm" light). As color temperature increases, the shading of the white light changes from red to yellow to white to blue. Color names used for modern CFLs and other tri-phosphor lamps vary between manufacturers, unlike the standardized names used with older halophosphate fluorescent lamps. For example, Sylvania's Daylight CFLs have a color temperature of 3500 K, while most other lamps called ''daylight'' have color temperatures of at least 5000 K. In United States, Energy Star's specification provides a set of named color temperatures for certified luminaries.


Lifespan

CFLs typically have a rated
service life A product's service life is its period of use in service. Several related terms describe more precisely a product's life, from the point of manufacture, storage, and distribution, and eventual use. Service life has been defined as "a product's ...
of 6000–15,000 hours, whereas standard incandescent lamps have a service life of 750 or 1000 hours. However, the actual lifetime of any lamp depends on many factors, including operating voltage, manufacturing defects, exposure to
voltage spike In electrical engineering, spikes are fast, short duration electrical transients in voltage (voltage spikes), current (current spikes), or transferred energy (energy spikes) in an electrical circuit. Fast, short duration electrical transients ...
s, mechanical shock, frequency of cycling on and off, lamp orientation, and ambient
operating temperature An operating temperature is the allowable temperature range of the local ambient environment at which an electrical or mechanical device operates. The device will operate effectively within a specified temperature range which varies based on the de ...
, among other factors. The life of a CFL is significantly shorter if it is turned on and off frequently or is used in a totally enclosed fixture. In the case of a 5-minute on/off cycle the lifespan of some CFLs may be reduced to that of incandescent light bulbs. The US Energy Star program suggests that fluorescent lamps be left on when leaving a room for less than 15 minutes to mitigate this problem. CFLs emit less light later in their lives than when they are new. The light output decay is exponential, with the fastest losses being soon after the lamp is first used. By the end of their lives, CFLs can be expected to emit 70–80% of their original light output. The response of the human eye to light is
logarithmic Logarithmic can refer to: * Logarithm, a transcendental function in mathematics * Logarithmic scale, the use of the logarithmic function to describe measurements * Logarithmic spiral, * Logarithmic growth * Logarithmic distribution, a discrete pr ...
. That is, while the human eye is highly sensitive to changes in the intensity of faint light sources, it is less sensitive to changes in the intensity of brighter light sources since the pupils compensate by dilating or constricting. So, presuming the illumination provided by the lamp was ample at the beginning of its life, and the light output of a bulb gradually decreases by 25%, viewers will perceive a much smaller change in light intensity. Fluorescent lamps get dimmer over their lifetime, so what starts out as an adequate luminosity may become inadequate. In one test by the U.S. Department of Energy, of ''Energy Star'' products in 2003–04, one quarter of tested CFLs no longer met their rated output after 40% of their rated service life.


Energy efficiency

Because the eye's sensitivity changes with the wavelength, the output of lamps is commonly measured in
lumens The lumen (symbol: lm) is the unit of luminous flux, a measure of the total quantity of visible light emitted by a source per unit of time, in the International System of Units (SI). Luminous flux differs from power ( radiant flux) in that radia ...
, a measure of the power of light as perceived by the human eye. The luminous efficacy of lamps is the number of lumens emitted for each watt of electric power used. The luminous efficacy of a typical CFL is 50–70 lumens per watt (lm/W) and that of a typical incandescent lamp is . Compared to a theoretical 100%-efficient lamp (), CFL lamps have lighting efficiency ranges of 7–10%, versus 1.5–2.5% for incandescents. Because of their higher efficacy, CFLs use between one-seventh and one-third of the power of equivalent incandescent lamps. Of 2010 world total lighting sales, 50 to 70 percent were incandescent. Replacing all inefficient lighting with CFLs would save per year, 2.5% of world electricity use. In the US, it is estimated that replacing all incandescents would save 80 TWh yearly. Since CFLs use much less energy than incandescent lamps (ILs), a phase-out of ILs would result in less
carbon dioxide Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is t ...
() being emitted into the atmosphere. Exchanging ILs for efficient CFLs on a global scale would achieve annual reductions of 230 Mt (million tons), more than the combined yearly emissions of the Netherlands and Portugal. If a building's indoor incandescent lamps are replaced by CFLs, the heat emitted due to lighting is significantly reduced. In warm climates, or in office or industrial buildings where
air conditioning Air conditioning, often abbreviated as A/C or AC, is the process of removing heat from an enclosed space to achieve a more comfortable interior environment (sometimes referred to as 'comfort cooling') and in some cases also strictly controlling ...
is often required, CFLs reduce the load on the cooling system when compared to the use of incandescent lamps, resulting in savings in electricity in addition to the energy efficiency savings of the lamps. However, in cooler climates in which buildings require heating, the
heating system A heating system is a mechanism for maintaining temperatures at an acceptable level; by using thermal energy within a home, office, or other dwelling. Often part of an HVAC (heating, ventilation, air conditioning) system. A heating system may be a ...
must replace the reduced heat from lighting fixtures. In
Winnipeg Winnipeg () is the capital and largest city of the province of Manitoba in Canada. It is centred on the confluence of the Red and Assiniboine rivers, near the longitudinal centre of North America. , Winnipeg had a city population of 749 ...
, Canada, it was estimated that CFLs would only generate 17% savings in energy compared to incandescent bulbs, as opposed to the 75% savings that could have been expected without space heating considerations.


Cost

While the purchase price of a CFL is typically 3–10 times greater than that of an equivalent incandescent lamp, a CFL lasts 8–15 times longer and uses two-thirds to three-quarters less energy. A US article stated "A household that invested $90 in changing 30 fixtures to CFLs would save $440 to $1,500 over the five-year life of the bulbs, depending on your cost of electricity. Look at your utility bill and imagine a 12% discount to estimate the savings." CFLs are extremely cost-effective in commercial buildings when used to replace incandescent lamps. Using average U.S. commercial electricity and gas rates for 2006, a 2008 article found that replacing each 75 W incandescent lamp with a CFL resulted in yearly savings of $22 in energy usage, reduced
HVAC Heating, ventilation, and air conditioning (HVAC) is the use of various technologies to control the temperature, humidity, and purity of the air in an enclosed space. Its goal is to provide thermal comfort and acceptable indoor air quality. ...
cost, and reduced labour to change lamps. The incremental capital investment of $2 per fixture is typically paid back in about one month. Savings are greater and payback periods shorter in regions with higher electric rates and, to a lesser extent, also in regions with higher than U.S. average cooling requirements. However, frequent on-off cycling (turning on and off) of CFLs greatly reduces their lifespan. The current price of CFLs reflects the manufacturing of nearly all CFLs in China, where labour costs less. In September 2010, the
Winchester, Virginia Winchester is the most north western independent city in the Commonwealth of Virginia. It is the county seat of Frederick County, although the two are separate jurisdictions. The Bureau of Economic Analysis combines the city of Winchester wit ...
,
General Electric General Electric Company (GE) is an American multinational conglomerate founded in 1892, and incorporated in New York state and headquartered in Boston. The company operated in sectors including healthcare, aviation, power, renewable energ ...
plant closed, leaving
Osram Sylvania Osram Sylvania Inc. is the North American operation of lighting manufacturer Osram. It was established in January 1993, with the acquisition of GTE’s Sylvania lighting division by Osram GmbH. In 2016, Osram spun off their general lighting busi ...
and the tiny American Light Bulb Manufacturing Inc. the last companies to make standard incandescent bulbs in the United States. At that time, Ellis Yan, whose Chinese company made the majority of CFLs sold in the United States, said he was interested in building a United States factory to make CFL bulbs, but wanted $12.5 million from the U.S. government to do so. General Electric had considered changing one of its bulb plants to make CFLs, but said that even after a $40 million investment in converting a plant, wage differences would mean costs would be 50% higher. According to an August 2009 newspaper report, some manufacturers claimed that CFLs could be used to replace higher-power incandescent lamps than justified by their light output. Equivalent wattage claims can be replaced by comparison of actual light output emitted by the lamp, which is measured in lumens and marked on the packaging.


Ballast Failure

In addition to the wear-out failure modes common to all fluorescent lamps, the electronic ballast may fail, since it has a number of component parts. Ballast failures are usually due to overheating and may be accompanied by discoloration or distortion of the ballast enclosure, odors, or smoke. The lamps are internally protected and are meant to fail safely at the end of their lives. Industry associations are working toward advising consumers of the different failure modes of CFLs compared to incandescent lamps, and to develop lamps with inoffensive failure modes. New North American technical standards aim to eliminate smoke or excess heat at the end of lamp life.


Dimming

Only some CFLs are labeled for dimming control. Using a dimmer with a standard CFL is ineffective and can shorten bulb life and void the warranty. Dimmable CFLs are available. The dimmer switch used in conjunction with a dimmable CFL must be matched to its power consumption range; many dimmers installed for use with incandescent bulbs do not function acceptably below 40 W, whereas CFL applications commonly draw power in the range 7–20 W. Dimmable CFLs have been marketed before suitable dimmers are available. The dimming range of CFLs is usually between 20% and 90%, but many modern CFLs have a dimmable range of 2% to 100%, more akin to that of incandescent lights. There are two types of dimmable CFL on the market: Standard dimmable CFLs, and "switch-dimmable" CFLs. The latter use a standard light switch, and the on-board electronics chooses the light output level based on the number of times the switch is turned on and off quickly. Dimmable CFLs are not a 100% replacement for incandescent fixtures that are dimmed for "mood scenes" such as wall sconces in a dining area. Below the 20% limit, the lamp may remain at 20% or flicker or the starter circuitry may stop and restart. Above 80%, the bulb may operate at 100%. However, recent products have solved these problems so that they perform more like incandescent lamps. Dimmable CFLs are more expensive than standard CFLs due to the additional circuitry. Cold-cathode CFLs can be dimmed to low levels, making them popular replacements for incandescent bulbs on dimmer circuits. When a CFL is dimmed, its color temperature (warmth) stays the same. This is counter to incandescent light sources, where color gets redder as the light source gets dimmer. The Kruithof curve from 1934 described an empirical relationship between intensity and color temperature of visually pleasing light sources.


Power factor

The input stage of a CFL is a rectifier, which presents a non-linear load to the power supply and introduces harmonic distortion on the current drawn from the supply. The use of CFLs in homes has no appreciable effect on power quality, but significant quantities of them in a large facility can have an adverse effect. The
power factor In electrical engineering, the power factor of an AC power system is defined as the ratio of the '' real power'' absorbed by the load to the '' apparent power'' flowing in the circuit. Real power is the average of the instantaneous product of ...
of CFLs does not significantly affect their energy-saving benefits for individual consumers, but their use in large numbers, such as in commercial applications or across millions of homes in a distribution system, could require infrastructure upgrades. In such cases, CFLs with low (below 30 percent) total harmonic distortion (THD) and power factors greater than 0.9 should be selected.


Infrared signals

Electronic devices operated by
infrared remote control In electronics, a remote control (also known as a remote or clicker) is an electronic device used to operate another device from a distance, usually wirelessly. In consumer electronics, a remote control can be used to operate devices such as ...
can interpret the infrared light emitted by CFLs as a signal; this may limit the use of CFLs near televisions, radios, remote controls, or
mobile phone A mobile phone, cellular phone, cell phone, cellphone, handphone, hand phone or pocket phone, sometimes shortened to simply mobile, cell, or just phone, is a portable telephone that can make and receive telephone call, calls over a radio freq ...
s. Energy Star certified CFLs must meet FCC standards, and so are required to list all known incompatibilities on the package.Can CFLs interfere with electronic equipment?
at ConsumerReports.org. Accessed 1 January 2008.


Outdoor use

CFLs are generally not designed or rated for outdoor use and some will not start in cold weather. CFLs are available with cold-weather ballasts, which may be rated to as low as −28.8 °C (−20 °F). Light output during the first few minutes of operation is limited at low temperatures before reaching full brightness. Cold-cathode CFLs will start and perform in a wide range of temperatures due to their different design.


Starting time

Incandescent lamps reach full brightness a fraction of a second after being switched on. , CFLs turn on within a second, but many still take time to achieve full brightness. The light color may be slightly different immediately after being turned on. Some CFLs are marketed as "instant on" and have no noticeable warm-up period, but others can take up to a minute to reach full brightness, or longer in very cold temperatures. Some that use a mercury amalgam can take up to three minutes to reach full output. This and the shorter life of CFLs when turned on and off for short periods may make CFLs less suitable for applications such as motion-activated lighting. Hybrid lamps, combining a halogen lamp with a CFL, are available where warm up time is unacceptable. The halogen lamp lights immediately, and is switched off once the CFL has reached full brightness.


Health and environmental impact


General

According to the European Commission Scientific Committee on Emerging and Newly Identified Health Risks (SCENIHR) in 2008, CFLs may pose an added health risk due to the
ultraviolet Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30  PHz) to 400 nm (750  THz), shorter than that of visible light, but longer than X-rays. UV radiati ...
and blue light emitted. This radiation could aggravate symptoms in people who already suffer skin conditions that make them exceptionally sensitive to light. The light emitted by some single-envelope CFLs at distances of less than could lead to ultraviolet exposures approaching the current workplace limit set to protect workers from skin and retinal damage. However, industry sources claim the UV radiation received from CFLs is too small to contribute to skin cancer and the use of double-envelope CFLs "largely or entirely" mitigates any other risks. Tests have shown that radiation exposure from CFLs is negligible at 150 centimeter distance from the source. At closer distances, comparisons show that CFLs emit less UVA (long wavelength) radiation than incandescent light bulbs. They do, however, emit higher levels of UVB (short wavelength) radiation. UVA can penetrate deep into the skin while sufficient levels of UVB can burn superficial layers. Closed (double-envelope) CFLs are shielded and emit a lower total UV radiation compared to incandescent or halogen bulbs of a similar wattage. For the average user, UV radiation from indoor lights does not appear to be a concern. For those with skin sensitivity long term indoor exposure may be a concern, in which case they may want to use a bulb with lower UV radiation output. There seems to be more variability within bulb types than between them, but the best option is shielded CFLs. A 2012 study comparing cellular health effects of CFL light and incandescent light found statistically significant cell damage in cultures exposed to CFL light. Spectroscopic analysis confirmed the presence of significant UVA and UVC radiation, which the study's authors conjectured was attributable to damage in the bulbs' internal phosphor coatings. No cellular damage was observed following exposure to incandescent light of equivalent intensity. The study's authors suggest that the ultraviolet exposure could be limited by the use of "double-walled" bulbs manufactured with an additional glass covering surrounding the phosphor-coated layer. When the base of the bulb is not made to be flame-retardant, as required in the voluntary standard for CFLs, overheating of the electrical components in the bulb may create a fire hazard.


Mercury content

CFLs, like all
fluorescent lamp A fluorescent lamp, or fluorescent tube, is a low-pressure mercury-vapor gas-discharge lamp that uses fluorescence to produce visible light. An electric current in the gas excites mercury vapor, which produces short-wave ultraviolet li ...
s, contain mercury as vapor inside the glass tubing. Most CFLs contain 3–5 mg per bulb, with the bulbs labeled "eco-friendly" containing as little as 1 mg. Because mercury is poisonous, even these small amounts are a concern for landfills and waste incinerators where the mercury from lamps may be released and contribute to air and water
pollution Pollution is the introduction of contaminants into the natural environment that cause adverse change. Pollution can take the form of any substance (solid, liquid, or gas) or energy (such as radioactivity, heat, sound, or light). Pollutants, the ...
. In the U.S., lighting manufacturer members of the National Electrical Manufacturers Association (NEMA) have voluntarily capped the amount of mercury used in CFLs. In the EU the same cap is required by the RoHS law. In areas where electric power is mostly generated in coal-fired stations, replacing incandescent bulbs by CFLs actually reduces mercury emissions. This is because the reduced electric power demand, reducing in turn the amount of mercury released by coal as it is burned, more than offsets the amount of mercury released from broken and discarded CFL bulbs. In July 2008 the U.S. EPA published a data sheet stating that the net system emission of mercury for CFL lighting was lower than for incandescent lighting of comparable lumen output. This was based on the average rate of mercury emission for U.S. electricity production and average estimated escape of mercury from a CFL put into a landfill. Coal-fired plants also emit other heavy metals, sulfur, and carbon dioxide. In the United States, the U.S. Environmental Protection Agency estimated that if all 270 million CFLs sold in 2007 were sent to landfill sites, around 0.13 metric tons of mercury would be released, 0.1% of all U.S. emissions of mercury (around 104 metric tons that year). The graph assumes that CFLs last an average of 8,000 hours regardless of manufacturer and premature breakage. In areas where coal is not used to produce energy, the emissions would be less for both types of bulb. Special handling instructions for breakage are not printed on the packaging of household CFL bulbs in many countries. The amount of mercury released by one bulb can temporarily exceed U.S. federal guidelines for chronic exposure. ''Chronic'', however, implies exposure for a significant time, and it remains unclear what the health risks are from short-term exposure to low levels of elemental mercury. Despite following EPA best-practice clean-up guidelines on broken CFLs, researchers were unable to remove mercury from carpet, and agitation of the carpet — such as by young children playing — created localized concentrations as high as 0.025 mg/m3 in air close to the carpet, even weeks after the initial breakage. The U.S. Environmental Protection Agency (EPA) has published best practices for cleanup of broken CFLs, and ways to avoid breakage, on its web site. It recommends airing out the room and carefully disposing of broken pieces in a jar. A Maine Department of Environmental Protection (DEP) study of 2008 comparing clean-up methods warns that using plastic bags to store broken CFL bulbs is dangerous, because vapors well above safe levels continue to leak from the bags. The EPA and the Maine DEP recommend a sealed glass jar as the best repository for a broken bulb. Since the end of 2018, the export, import and manufacture of CFLs within the European Union has been prohibited under the EU Mercury Regulation.


Recycling

Health and environmental concerns about mercury have prompted many jurisdictions to require spent lamps to be properly disposed of or recycled, rather than being included in the general waste stream sent to landfills. Safe disposal requires storing the bulbs unbroken until they can be processed. In the
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., federal district, five ma ...
, most states have adopted and currently implement the federal Universal Waste Rule (UWR). Several states, including
Vermont Vermont () is a state in the northeast New England region of the United States. Vermont is bordered by the states of Massachusetts to the south, New Hampshire to the east, and New York to the west, and the Canadian province of Quebec to the ...
,
New Hampshire New Hampshire is a state in the New England region of the northeastern United States. It is bordered by Massachusetts to the south, Vermont to the west, Maine and the Gulf of Maine to the east, and the Canadian province of Quebec to the nor ...
,
California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the ...
,
Minnesota Minnesota () is a state in the upper midwestern region of the United States. It is the 12th largest U.S. state in area and the List of U.S. states and territories by population, 22nd most populous, with over 5.75 million residents. Minne ...
, New York,
Maine Maine () is a U.S. state, state in the New England and Northeastern United States, Northeastern regions of the United States. It borders New Hampshire to the west, the Gulf of Maine to the southeast, and the Provinces and territories of Canad ...
,
Connecticut Connecticut () is the southernmost state in the New England region of the Northeastern United States. It is bordered by Rhode Island to the east, Massachusetts to the north, New York to the west, and Long Island Sound to the south. Its cap ...
and
Rhode Island Rhode Island (, like ''road'') is a state in the New England region of the Northeastern United States. It is the smallest U.S. state by area and the seventh-least populous, with slightly fewer than 1.1 million residents as of 2020, but i ...
, have regulations that are more stringent than the federal UWR. Home-supply
chain store A chain store or retail chain is a retail outlet in which several locations share a brand, central management and standardized business practices. They have come to dominate the retail and dining markets and many service categories, in many ...
s make free CFL recycling widely available. In the
European Union The European Union (EU) is a supranational political and economic union of member states that are located primarily in Europe. The union has a total area of and an estimated total population of about 447million. The EU has often been ...
, CFLs are one of many products subject to the
WEEE The Waste Electrical and Electronic Equipment Directive (WEEE Directive) is the European Community Directive 2012/19/EU on waste electrical and electronic equipment (WEEE) which, together with the RoHS Directive 2011/65/EU, became European La ...
recycling scheme. The retail price includes an amount to pay for recycling, and manufacturers and importers have an obligation to collect and recycle CFLs. According to the Northwest Compact Fluorescent Lamp Recycling Project, because household users in the U.S. Northwest have the option of disposing of these products in the same way they dispose of other solid waste, in Oregon "a large majority of household CFLs are going to municipal solid waste". They also note the EPA's estimates for the percentage of fluorescent lamps' total mercury released when they are disposed of in the following ways: municipal waste landfill 3.2%, recycling 3%, municipal waste incineration 17.55% and hazardous waste disposal 0.2%. The first step of processing CFLs involves crushing the bulbs in a machine that uses negative pressure ventilation and a mercury-absorbing filter or
cold trap In vacuum applications, a cold trap is a device that condenses all vapors except the permanent gases into a liquid or solid. The most common objective is to prevent vapors being evacuated from an experiment from entering a vacuum pump where the ...
to contain mercury vapor. Many municipalities are purchasing such machines. The crushed glass and metal is stored in drums, ready for shipping to recycling factories.


Greenhouse gases

In some places, such as
Quebec Quebec ( ; )According to the Government of Canada, Canadian government, ''Québec'' (with the acute accent) is the official name in Canadian French and ''Quebec'' (without the accent) is the province's official name in Canadian English is ...
and
British Columbia British Columbia (commonly abbreviated as BC) is the westernmost Provinces and territories of Canada, province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include ...
in 2007,
central heating A central heating system provides warmth to a number of spaces within a building from one main source of heat. It is a component of heating, ventilation, and air conditioning (short: HVAC) systems, which can both cool and warm interior spaces. ...
for homes was provided mostly by the burning of
natural gas Natural gas (also called fossil gas or simply gas) is a naturally occurring mixture of gaseous hydrocarbons consisting primarily of methane in addition to various smaller amounts of other higher alkanes. Low levels of trace gases like carbon ...
, whereas electricity was primarily provided by hydroelectric power. An analysis of the impacts of a ban on incandescent light bulbs at that time introduced the notion that in such areas, heat generated by conventional electric light bulbs may have been significantly reducing the release of greenhouse gases from natural gas heating. Ivanco, Karney, and Waher estimated that "If all homes in Quebec were required to switch from (incandescent) bulbs to CFLs, there would be an increase of almost 220,000
tonne The tonne ( or ; symbol: t) is a unit of mass equal to 1000  kilograms. It is a non-SI unit accepted for use with SI. It is also referred to as a metric ton to distinguish it from the non-metric units of the short ton ( United State ...
s in CO2 emissions in the province, equivalent to the annual emissions from more than 40,000 automobiles."


Use and adoption

CFLs are produced for both
alternating current Alternating current (AC) is an electric current which periodically reverses direction and changes its magnitude continuously with time in contrast to direct current (DC) which flows only in one direction. Alternating current is the form in which ...
(AC) and
direct current Direct current (DC) is one-directional flow of electric charge. An electrochemical cell is a prime example of DC power. Direct current may flow through a conductor such as a wire, but can also flow through semiconductors, insulators, or eve ...
(DC) input. DC CFLs are popular for use in
recreational vehicle A recreational vehicle, often abbreviated as RV, is a motor vehicle or trailer that includes living quarters designed for accommodation. Types of RVs include motorhomes, campervans, coaches, caravans (also known as travel trailers and camp ...
s and off-the-grid housing. Various aid agency initiatives exist in
developing countries A developing country is a sovereign state with a lesser developed Industrial sector, industrial base and a lower Human Development Index (HDI) relative to other countries. However, this definition is not universally agreed upon. There is al ...
to replace kerosene lamps, which have associated health and safety hazards, with CFLs powered by batteries, solar panels or
wind power Wind power or wind energy is mostly the use of wind turbines to generate electricity. Wind power is a popular, sustainable, renewable energy source that has a much smaller impact on the environment than burning fossil fuels. Historicall ...
generators.200 0000+ solar powered kerosene-lamp replacements assisted by aid agencies: http://www.ashdenawards.org/winners/mpgvm , http://www.ashdenawards.org/winners/Dlight10 , Due to the potential to reduce electric consumption and pollution, various organizations have encouraged the adoption of CFLs and other efficient lighting. Efforts range from publicity to encourage awareness, to direct handouts of CFLs to the public. Some electric utilities and local governments have subsidized CFLs or provided them free to customers as a means to reduce electric demand; and so delay further investments in generation. In the United States, the ''Program for the Evaluation and Analysis of Residential Lighting'' (PEARL) was created to be a watchdog program. PEARL has evaluated the performance and Energy Star compliance of more than 150 models of CFL bulbs. The UN Environment Programme (UNEP)/Global Environment Facility (GEF) initiative has developed "The Global Efficient Partnership Program", which focuses on country-led policies and approaches to enable the implementation of energy-efficient lighting, including CFLs, quickly and cost-effectively in developing and emerging countries. In the United States and Canada, the Energy Star program labels lamps that meet a set of standards for efficiency, 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. Those CFLs with a recent Energy Star certification start in less than one second and do not flicker. ''Energy Star Light Bulbs for Consumers'' is a resource for finding and comparing Energy Star qualified lamps. There is ongoing work in improving the "quality" ( color rendering index) of the light. In the United States, new standards proposed by the
United States Department of Energy The United States Department of Energy (DOE) is an executive department of the U.S. federal government that oversees U.S. national energy policy and manages the research and development of nuclear power and nuclear weapons in the United Stat ...
could result in LED lamps replacing CFLs. In the opinion of Noah Horowitz of the
Natural Resources Defense Council The Natural Resources Defense Council (NRDC) is a United States-based 501(c)(3) non-profit international environmental advocacy group, with its headquarters in New York City and offices in Washington D.C., San Francisco, Los Angeles, Chicago, ...
, most CFL bulbs would not meet the standards. In the
United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the European mainland, continental mainland. It comprises England, Scotlan ...
, a similar program is run by the Energy Saving Trust to identify lighting products that meet energy conservation and performance guidelines. The G24 (624Q2) and GU24 lamp fitting socket systems were designed to replace the traditional lamp sockets, so that incandescent bulbs are not installed in fixtures intended for energy efficient lamps only.


Efficiency comparison


See Also

*
Fluorescent lamp A fluorescent lamp, or fluorescent tube, is a low-pressure mercury-vapor gas-discharge lamp that uses fluorescence to produce visible light. An electric current in the gas excites mercury vapor, which produces short-wave ultraviolet li ...
* List of plasma physics articles


References


External links


CFL Bulb and Base Reference Guide

Plug-In Plug-in CFL (PL Type) Lamps: Non-integrated Bulbs
– cross reference listing of non-integrated CFL bulbs
A technical description of a typical CFL circuit
{{Artificial light sources, state=collapsed Energy-saving lighting Fluorescence Gas discharge lamps 20th-century inventions General Electric inventions