Compact fluorescent lamp

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A spiral type compact fluorescent light bulb. Despite the slightly reduced efficiency of this style CF bulb due to the inherently excessive thick layer of phosphor on the lower side of the twist, it has remained one of the most popular among North American consumers since its introduction in the mid 1990s.[1]

A compact fluorescent lamp (CFL), also known as a compact fluorescent light bulb or an energy saving lightbulb, is a type of fluorescent lamp that fits into a standard light bulb socket or plugs into a small lighting fixture.

In comparison to incandescent light bulbs, CFLs have a longer rated life and use less electricity. CFLs might save enough money in electricity costs to make up for their higher initial price within about 500 hours of use, although the continuing decrease in the price of incandescent bulbs is increasing the payback time.

[edit] Market

Globally introduced in the early 1980s, CFLs have steadily increased in sales volume. The most important advance in fluorescent lamp technology (including in CFLs) has been the gradual replacement of magnetic ballasts with electronic ballasts: This has removed most of the flickering and slow starting traditionally associated with fluorescent lighting.

The market for CFLs has been aided by the production of both integrated and non-integrated lamps. Integrated lamps combine a bulb, an electronic ballast and either a screw or bayonet fitting; these lamps allow consumers to easily replace incandescent bulbs with CFLs. Non-integrated lamps allow for the replacement of consumable bulbs and the extended use of ballasts; since the ballasts last longer, they can be more expensive and sophisticated, providing options such as dimming. (Non-integrated CFLs are more popular for professional users, such as hotels.)

CFLs are produced for both AC input and DC input. DC CFLs are popular for use in recreational vehicles and off-the-grid housing. Poor families in developing countries are using DC CFLs (with car batteries and small solar panels) to replace kerosene lanterns.

CFLs can also be operated with solar-powered streetlights, using solar panels located on the top or sides of a pole and luminaires that are specially wired to use the lamps.

[edit] CFL lifespan, energy consumption and costs compared to incandescent bulbs

[edit] Lifespan

Modern CFLs typically have a life span specified between 8,000 and 15,000 hours.^[1] Typical domestic incandescent bulbs are similarly specified to have a life of 1000 hours.^[2] These lifetimes are often specified according to IEC60969,^[3] which specifies that "life to 50% of failures shall be not less than value declared by the manufacturer". In practice the lifetime of any actual light bulb, CFL or incandescent, depends on many factors including random statistical effects, manufacturing defects, exposure to voltage spikes, mechanical shock, frequency of cycling on and off, ambient operating temperature and many other factors.

[edit] Energy consumption

CFLs use about 20% of the power, and so in the simplest case when compared with incandescent bulbs, they can be responsible for about an 80% reduction in electricity costs and therefore also in the environmental impact of generating that electricity. For example, many 11-watt CFLs are specified to produce the same amount of light as 60-watt incandescent bulbs (approximately 900 lumens).

Such a simple calculation does not take into account the other effects of light bulb heat on energy costs. The energy consumed by any light bulb is ultimately converted into heat energy in its immediate environment. During cold months, the more power-hungry bulbs therefore help to heat buildings; but during hot months, they not only waste power directly, but may also place additional strain on air conditioning systems.

Even when the heat produced may be welcome, in many cases light bulbs do not provide it in the most efficient way. Light fittings are usually fixed high in the room, where convection will not help to distribute the heat to the occupants. Many buildings also generally use less expensive, more environmentally friendly or more efficient sources of heat than electricity for heating.

[edit] Cost

In addition to the above savings on energy costs, CFLs last approximately 8 to 15 times longer than an equivalent incandescent on average, thus requiring that fewer bulbs be purchased. They may, however, result in higher heating or lower cooling requirements, which would affect the savings. Looking only at monetary costs, a CFL will typically repay its initial higher cost much faster than the prevailing interest rate.

[edit] Colors

A photograph of various light bulbs illustrates the effect of color temperature differences (left to right): 1. Compact Fluorescent: General Electric, 13 watt, 6500 K; 2. Incandescent: Sylvania 60-Watt Extra Soft White; 3. Compact Fluorescent: Bright Effects, 15 watts, 2644 K; 4. Compact Fluorescent: Sylvania, 14 watts, 3000 K

Color temperature can be indicated in Kelvin or Mired (1 million divided by the colour temperature in Kelvin).

Color temperature is a quantitative measure. The higher the number in Kelvin, the “cooler”, i.e., bluer, the shade. Color names associated with a particular color temperature are not standardized for modern CFLs and other triphosphor lamps like they were for the older style halophosphate fluorescent lamps. Variations and inconsistencies exist among manufacturers. For example, Sylvania's Daylight CFLs have a color temperature of 3500 K, while most other bulbs with a "daylight" label have color temperatures of at least 5000 K. Some vendors do not include the kelvin value on the package, but this is beginning to change now that the Energy Star Criteria for CFLs is expected to require such labeling in its 4.0 revision.

CFLs are also produced, less commonly, in other colors:

• Red, green, orange, blue, and pink, primarily for novelty purposes
• Yellow, for outdoor lighting, because it does not attract insects
• Blacklight (UV light) for special effects

CFLs with UVA generating phosphor, are an efficient source of long wave ultraviolet "blacklight", much more efficient than incandescent "blacklight" bulbs, since the amount of UV light that the filament of the incandescent lamp produces is according to blackbody radiation, and the UV radiation is only a fraction of the generated spectrum.

Being a gas discharge lamp, a CFL will not generate all frequencies of visible light; the actual color rendering index is a design compromise (see below). With less than perfect color rendering, CFLs can be unsatisfactory for inside lighting, but modern, high quality designs are proving acceptable for home use.

Other terms that apply to CFLs:

• Full Spectrum
• High Definition

To many consumers, however, fluorescent lights provide a harsh and garish light compared with the typical incandescent lamp. This is an important factor in the resistance by the public to use CFLs. Other factors include the great expense, the slow response time, a key problem for consumer safety, and the possibility of ultra-violet emissions from fluorescent lamps. The emissions can cause serious damage to light sensitive pigments in paintings and textiles, for example. The cost differential has widened in 2006/7 with the widespread import of very cheap and compact incandescent bulbs from the far east. It is unlikely that fluorescent bulbs of the same small size will be available in the near, or even distant future.

[edit] Environmental issues

Since CFLs use less power to supply the same amount of light as an incandescent lamp of the same lumen rating, they can be used to decrease overall energy consumption. Generation of electricity is a major source of pollution in various forms. According to Environment Canada:

"The electricity sector is unique among industrial sectors in its very large contribution to emissions associated with nearly all air issues. Electricity generation produces a large share of Canadian nitrogen oxides and sulphur dioxide emissions, which contribute to smog and acid rain and the formation of fine particulate matter. It is the largest uncontrolled industrial source of mercury emissions in Canada. Fossil fuel-fired electric power plants also emit carbon dioxide, which contributes to climate change. In addition, the sector has significant impacts on water and habitat and species. In particular, hydro dams and transmission lines have significant effects on water and biodiversity." ^[4]

Mercury use of compact fluorescent bulb vs. incandescent bulb when powered by electricity generated from coal.

CFLs contain small amounts of mercury^[5][6] and it is a concern for landfills and waste incinerators where the mercury from lamps may be released and contribute to air and water pollution. In the USA, lighting manufacturer members of the National Electrical Manufacturers Association (NEMA) have made a voluntary commitment to cap the amount of mercury used in CFLs:

Under the voluntary commitment, effective April 15, 2007, NEMA members will cap the total mercury content in CFLs of less than 25 watts at 5 milligrams (mg) per unit. The total mercury content of CFLs that use 25 to 40 watts of electricity will be capped at 6 mg per unit.^[7]

Some manufacturers such as Philips and GE make very low mercury content CFLs.^[8] Safe disposal requires storing the bulbs unbroken until they can be processed. Consumers should seek advice from local authorities. Usually, one can either:

• Return used CFLs to where they were purchased, so the store can recycle them correctly; or
• Take used CFLs to a local recycling facility.

The first step of processing involves crushing the bulbs in a machine that uses negative pressure ventilation and a mercury-absorbing filter or cold trap to contain and treat the contaminated gases. Many municipalities are purchasing such machines. The crushed glass and metal is stored in drums, ready for shipping to recycling factories.

Note that coal power plants are the "the largest uncontrolled industrial source of mercury emissions in Canada". ^[9] According to the Environmental Protection Agency (EPA), (when coal power is used) the mercury released from powering an incandescent bulb for five years exceeds the sum of the mercury released by powering a comparably luminous CFL for the same period and the mercury contained in the lamp.^[10] It should be noted, however that the "EPA is implementing policies to reduce airborne mercury emissions. Under regulations issued in 2005, coal-fired power plants will need to reduce their emissions by 70 percent by 2018."^[11]. This change will lengthen the term before CFLs are better than incandescents. If CFLs are recycled and the mercury reclaimed, the equation tilts towards CFLs, and if non-coal sources of electricity are used, the equation tilts toward incandescents.

[edit] How they work

[edit] Parts

Electronic ballast of a compact fluorescent lamp

There are two main parts in a CFL: the gas-filled tube (also called bulb or burner) and the magnetic or electronic ballast. Electrical energy in the form of an electrical current from the ballast flows through the gas, causing it to emit ultraviolet light. The ultraviolet light then excites a white phosphor coating on the inside of the tube. This coating emits visible light. CFLs that flicker when they start have magnetic ballasts; CFLs with electronic ballasts are now much more common. See Fluorescent lamp.

[edit] End of life

Both the ballast and the burner are subject to failure from normal use. In low-quality CFLs, high temperatures often cause the ballast electronics to fail before the burners. In high-quality CFLs, the burners almost always fail first. The burners occasionally fail due to cracks and imperfect seals but much more typically due to an increased work function at the electrodes caused by vaporization and sputtering-off of the cathode material. It is also this material that then deposits onto the burner's glass tubing, causing blackening of the tubing.

High-quality driver electronics can prolong the life of the burners by preheating the electrodes to prevent damage from rapid expansion. High-quality drivers require high-quality components. The best CFL manufacturers (including Osram, Philips, General Electric, Luxlite) produce CFLs that can last 15,000 hours. Such lifetimes require highly automated and controlled manufacturing.

At end of life, CFLs should be recycled by specialist firms. In the European Union, CFL lamps are one of many products subject to the WEEE recycling scheme. The retail price includes an amount to pay for recycling, and manufacturers and importers have an obligation to collect and recycle CFL lamps.

[edit] Design compromises and challenges

Apart from durability, the primary purpose of good CFL design is high electrical efficiency.

These are some other areas of interest:

• Quality of light: A phosphor emits light in a narrow frequency range, unlike an incandescent filament, which emits the full spectrum, though not all colors equally, of visible light. Mono-phosphor lamps emit poor quality light; colors look bad and inaccurate. The solution is to mix different phosphors, each emitting a different range of light. Properly mixed, a good approximation of daylight or incandescent light can be reached. However, every extra phosphor added to the coating mix causes a loss of efficiency (and longer "warm up" times) and increased cost. Good-quality consumer CFLs use three or four phosphors—typically emitting light in the red, green and blue spectra—to achieve a "white" light with color rendering indexes (CRI) of around 80 although CFLs with a CRI as great as 93 have been developed. (A CRI of 100 represents the most accurate reproduction of all colors; reference sources having a CRI of 100, such as the sun and tungsten bulbs, emit black body radiation.)
• Size: CFL light output is roughly proportional to phosphor surface area, and high output CFL bulbs are often larger than their incandescent equivalents. This means that the CFL might work fine in the socket, but that the light cover might not fit over it or that the user might not have the room to squeeze the CFL in place.
• Covered performance: To approximate the look of an incandescent bulb, the CFL burner can be enclosed behind a cosmetic glass cover. However, this causes the temperature of the burner to increase greatly, increasing the gas pressure inside the burner and decreasing the brightness (and therefore efficiency) of the lamp. These problems have largely been solved using special mercury compounds and other techniques, and now globe and flood versions are widely available (at hardware stores and elsewhere).
• Electronics: Dimming control can be added to the lamp with support from the driver electronics. Also, large deployments of CFLs (in a hotel lobby, for example) require specialised electronics with low levels of electronic distortion to avoid disturbing the electricity supply.^[12] This is usually not a problem with home use because of the few lamps deployed. One problem with dimmable compact fluorescents is that when they dim the color temperature stays the same. This means that a dimmed light appears grey instead of warm orange like an incandescent light when dimmed.^{[citation needed]}
• Time to achieve full brightness: Compact fluorescent bulbs can take 30 seconds or more to reach full brightness. (This compares to 0.1 seconds for incandescent bulbs and 0.01 seconds for LED lamps) In practice this varies widely between brands/types. It is more of a problem with older lamps, "Warm (colour) tone" lamps and at low ambient temperatures.
• CFLs often do not fail suddenly, as incandescent lightbulbs do. Symptoms of impending CFL failure may come months ahead, with more and more prolonged turn-on times until full luminosity is reached, buzzing of the ballast, random periods of reduced brightness and the appearance of growing black spots on the glass tubing's inside.
• In places infested with insects, or in an outdoor environment, bugs have a habit of climbing into the "cage" formed by the CFL tubing and perishing inside. Some CFLs have an extra oval shell hiding the tubeworks to prevent this.
• Buzz: The newer spiral lights have very low hum or buzz, but in a very quiet room can still be heard.
• Outdoor Use: In very cold weather the time to full brightness can be extended to several minutes or not turn on at all.
• Differences among manufacturers: There are large differences among quality of light, cost, and turn-on time among different manufacturers, even for bulbs that appear identical and have the same color temperature.
• Availability of high output versions: CFLs rated greater than 23 watts (said to be equivalent to a 120 watt incandescent bulb) can be difficult to find. However incandescent bulb of 150 or even 200 watts are widely available.
• RFI/EMC issues: Because of the way in which they operate CFLs tend to produce a certain amount of harmonic energy on the power line which can lead to interference problems on AM radio although the severity of this varies between brands.
• There are consumer safety problems with the use of any fluorescent lights in hazardous areas in the home, such as kitchens, stairs, and bathrooms, especially for the elderly and infirm. Due to the slowness in achieving full brightness, the user may be unaware of imminent hazards, such as a broken glass or loose rug. After the road, the home is the most hazardous area for the public, so CFLs should be considered carefully before installation.

[edit] Other CFL technologies

Another type of fluorescent lamp is the electrodeless fluorescent, known as a radiofluorescent lamp or fluorescent induction lamp. Unlike virtually all other conventional lamps that have hardwired electrical connections to transfer energy to the lamp core, the electrodeless fluorescent accomplishes this solely by electromagnetic induction. The induction is effected by means of a wire-wound ferrite core that projects upward into the bulb encased in an inverted U-shaped glass cover. The wire is energized with high frequency electricity often 2.65 or 13.6 MHz; this ionizes the mercury vapor, exciting the phosphor & producing light.

Another variation on existing CFL technologies are bulbs with an external nano-particle coating of titanium dioxide. Titanium dioxide is a photocatalyst, becoming ionized when exposed to UV light produced by the CFL. It is thereby capable of converting oxygen to ozone and water to hydroxyl radicals, which neutralize odors and kill bacteria, viruses, and mold spores.

The Cold Cathode Fluorescent Light (CCFL) is one of the newest forms of CFL. CCFLs use electrodes without a filament. The voltage of CCFL lamps is about 5 times higher than CFL lamps and the current is about 10 times lower. CCFL lamps have a diameter of about 3 millimeters. The lifetime of CCFL lamps is about 50,000 hours. The lumens-per-watt value is about half of CFL lamps.

Initially CCFL was used for thin monitors and backlighting, but now it is also manufactured for use as a lightbulb. Since the efficacy (lumen/watt) is actually lower than a compact fluorescent light, it is actually not as efficient as a CFL. Its advantages are that it (1) is instant-on, like an incandescent, (2) is compatible with timers, photocells, and dimmers, and (3) has an amazingly long life of approximately 50,000 hours. CCFL are a convenient transition-technology for those who are not comfortable with the short lag-time associated with the initial lighting of Compact Fluorescents. They are also an effective and efficient replacement for lighting that is turned on and off frequently with little extended use (e.g. a half-bath or closet).

[edit] Efforts to encourage adoption

Campaigns to improving the efficiency of household lighting are part of the wider effort to increase energy efficacy.[2]

In the UK, some activists in Britain have lobbied Parliament to tax or ban incandescent bulbs, a measure that has generated controversy, and websites like Banthebulb.org have been created in support of the ban. The Government itself focuses its efforts to improve household energy efficiency through its establishment and funding of the Energy Saving Trust. However, there are concerns over consumer safety in the home because of the low reaction time of CFLs. The elderly and infirm are at risk from slip and fall accidents when the poor light prevents them seeing obstacles or hazards.

In an attempt to slash emissions, the Australian federal government plans to phase out the use of incandescent light bulbs by 2010, the first government to do so in the world.^[13].^[14] In addition the Australian government have published an Energy saving calculator in order to help people calculate their individual benefits.

In Holland, Greenpeace are attempting to mobilize people to change 1 million light bulbs to CFLs.

In Ottawa, Canada, there is an effort to get every household to change at least one light bulb. Project Porchlight has volunteers going door-to-door providing one CF bulb to every household for free.

The U.S. Environmental Defense initiated a campaign in June 2006 called Make the Switch to encourage the public to switch from incandescent bulbs to compact fluorescent bulbs. It asked every household in the U.S. to replace three 60-watt incandescent bulbs with CFLs. Environmental Defense claims that if every household were to do this, the change could reduce pollution as much as taking 3.5 million cars off the road would.

Wal-Mart announced in September 2006 that it was starting a campaign to endorse CFLs. The store aims to sell one CFL to every one of their 100 million customers within the next year, thus changing the energy consumption of the United States and improving Wal-Mart's reputation.^[15].

A California Assemblyman, Lloyd Levine, wants to introduce a bill to ban all conventional light bulbs from the State of California (NewScientist)

In February 2007, the 18seconds campaign was launched with leaders from business (Yahoo! and Walmart) and US Government (EPA and DOE) to increase awareness of energy-efficient light bulbs as a way to slow global climate change . The coalition was named 18seconds to reflect the amount of time it takes for one person to change a light bulb. To coincide with the launch of this campaign, Yahoo has created a Web site 18seconds.org that will track bulb sales and energy savings nationwide and encourage bulb-switching competition among cities and states.^[16]

In South Africa the main electricity supply company Eskom has launched a program to exchange incandescent bulbs for CFL bulbs for free. Its aim is to reduce the electrical demand at peak times. [3]

Another website, Onebillionbulbs.com, is behind a campaign to replace one billion incandescent bulbs with CFLs across the U.S. The site has a fifty-state map; each state is a certain color from white to green. The closer to green, the closer to the state's goal.

However, people have been hesitant to transition from incandescent bulbs to CFLs, despite their three- to twelve-month payback period. The initial capital investment is higher, which may deter some people. The warm-up period associated with CFLs discourages others (although the new CCFL mitigate that objection). Professionals who install lighting fixtures sometimes do not consider installing CFLs, because the electrical bill is not their concern, and the CFLs have a higher cost.

There are several special cases where CFLs should not be used:

- CFLs burn out in a few weeks if used in motion-detector security lights.

- CFLs don't work right for television and theater stage lighting. The dimmers don't dim CFLs properly, the CFLs won't light or burn out quickly, and the lens systems in spotlights won't focus a CFL to a smooth pool of light.

- There are other uses for incandescent lamps in electronic circuits. Such uses include positive temperature coefficient resistances, ballasts, and protective load circuits in audio power amplifiers and electrostatic air filters. A CFL would prevent the electronic device from working.

[edit] Gallery of CFLs

Biax or Linear CFL	Globe CFL	Reflector CFL	Spiral CFL
A CFL bulb designed to resemble an incandescent bulb. An incandescent bulb is shown on the right for comparison

[edit] References

[edit] Notes

• R. J. Van der Plas, A. B. de Graaff, "A comparison of lamps for domestic lighting in developing countries" (Energy Ser. Pap. 6, Industry and Energy Department, World Bank, Washington, DC, 1988).
• G. S. Dutt, "Illumination and Sustainable Development", Energy Sustain Dev. 1 (1), 23 (1994).

[edit] External links

• Compact Fluorescent Lamps: What You Should Know
• How much coal is required to run a 100-watt light bulb 24 hours a day for a year? - from HowStuffWorks.com
• Energy Savings
• Compact Fluorescent Pitfalls, Reality, and Recommendations
• Lighting Research Center - Excellent information and analysis of "full spectrum" lighting
• US Government Energy Star's page on fluorescent bulbs
• LampRecycle.Org - For information on recycling spent mercury-containing lamps
• Mercury in Compact Fluorescent Lamps - from the National Electrical Manufacturers Association
• Lighting and the environment:A personal view of environmental considerations in lighting design. - a good overview of some of the criticisms of CFLs
• Should There be a Ban on Incandescent Lamps? - another one-person overview, but with some solid measurements.
• Typical Lumen Outputs and Energy Costs for Outdoor Lighting
• Dimwit politicians try to ban incandescent bulbs - news story
• What would happen if every household changed from ordinary light bulbs to CFL light bulbs?

Lighting and Lamps v • d • e
Incandescent:	Conventional - Halogen - Parabolic aluminized reflector (PAR)
Fluorescent:	Compact fluorescent (CFL) - Linear fluorescent - Induction lamp
Gas discharge:	High-intensity discharge (HID) - Mercury-vapor - Metal-halide - Neon - Sodium vapor
Electric arc:	Arc lamp - HMI - Xenon arc - Yablochkov candle
Combustion:	Acetylene/Carbide - Candle - Gas lighting - Kerosene lamp - Limelight - Oil lamp - Safety lamp - Petromax
Other types:	Sulfur lamp - Light-emitting diode (LED) - LED lamp (SSL) - Fiber optics - Plasma - El wire