Compact fluorescent lamp: Difference between revisions

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A spiral type compact fluorescent lamp. Despite the slightly reduced efficiency of this style CFL because of 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.

A compact fluorescent lamp (CFL), also known as a compact fluorescent light bulb or an energy saving lightbulb, is a type of lamp (light bulb) designed to fit into roughly the same space as an incandescent lamp, but with the advantages of a fluorescent lamp. Many CFLs can directly replace an existing incandescent lamp.

Compared to incandescent lamps of the same luminous flux, CFLs have a longer rated life and use less energy. A CFL can save over US$30 in electricity costs over the lamp’s lifetime compared to an incandescent lamp. However, the initial purchase price of a CFL is often significantly higher than an incandescent lamp of the same output (but this cost is quickly recouped in energy savings assuming average bulb use).

Although CFLs do radiate a different spectrum of light than incandescent lamps, recent technological advances have reduced that difference dramatically. The light emitted by "soft white" CFLs available today are, for practical purposes, indistinguishable from standard bulbs.

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 lamps 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 street lights, using solar panels located on the top or sides of a pole and luminaires that are specially wired to use the lamps.

Comparison with incandescent lamps

Lifespan

Modern CFLs typically have a life span of between 8,000 and 15,000 hours, whereas incandescent lamps are usually manufactured to have a life span of 750 hours or 1000 hours. These lifetimes are quoted according to IEC60969, which specifies that "life to 50% of failures shall be not less than value declared by the manufacturer". Some incandescent lamps have shorter designed lifespans, such as those used for lighting photographic studios and used in overhead projectors. In practice the lifetime of any actual lamp, CFL or incandescent, depends on many factors including manufacturing defects, exposure to voltage spikes, mechanical shock, frequency of cycling on and off and ambient operating temperature, among other factors.

Energy consumption

Initial luminous flux (light output)	consumption of electricity
	Incandescent 240V	Compact fluorescent	Incandescent 120V	LV Halogen 12V
Lifetime	1,000hr	15,000hr	Variable	4,000hr
90 lm	15 W	-	-	-
240 lm	-	5 W	-	-
400 lm	-	7 W	-	-
415 lm	40 W	-	-	-
505 lm	-	-	40 W (1000hr)	-
660 lm	-	11 W	-	-
700 lm	60 W	-	-	-
865 lm	-	-	60 W (1000hr)	-
900 lm	-	14-15 W	-	35 W
930 lm	75 W	-	-	-
1190 lm	-	-	75 W (750hr)	-
1230 lm	-	20 W	-	-
1250 lm	-	-	-	50 W
1330 lm	100 W	-	-	-
1500 lm	-	23 W	-	-
1700 lm	-	-	-	65 W
1710 lm	-	-	100 W (750hr)	-
1900 lm	-	30 W	-	-
2140 lm	150 W	-	-	-
2990 lm	200 W	-	-	-
All 240V Incandescent,CFL and LV Halogen data taken from Osram website http://catalog.myosram.com at 2007-04-14. Lamps are: - "CLAS A FR xxW 240V B22D FS1" for incandescent - "DEL LL xxW/827 220-240V E27 FS1" for CFL, and - "64432 IRC xxW 12V GY6,35 FS1" for Low Voltage Halogen with the xx replaced by the various wattages. 240V lamps have slightly lower lumen outputs than 230V lamps, and the DEL LL variant of the CFLs are more efficient than the DEL EL variant. All 120V Incandescent data taken from GE Lighting website http://www.gelighting.com/na/business_lighting/products/ at 2007-04-14. Lamps are: - GE Basic A19 E26 120V xxW -with the xx replaced by the various wattages. 14 watt CFLs rated at 900 lumens by the manufacturer are: - n:vision EDXO-14 and - Commercial Electric EDS0-14.

For a given light output, CFLs use between one-fifth and one-quarter of the power of an equivalent incandescent lamp, thereby saving significant amounts of energy and reducing the need for electrical generation. For industrialized countries, lighting makes up about one fifth of electricity consumption, so there are potentially significant benefits.

Incandescent lamps are less efficient than CFLs because incandescent lamps convert approximately 90% of the energy they consume into heat (compared to 30% for a CFL).

Lighting accounted for approximately 9% of household electricity usage in the United States in 2001. If widespread use of CFLs could save three-quarters to four-fifths of this, it would amount to a total energy saving of about 7% from household usage.

Energy efficiency

Further information: Luminous efficacy

In order to compare the actual energy efficiency of CFLs with various other bulb technologies such as incandescent, LED and halogen, it is necessary to consider their luminous efficacy, including the subjective usefulness of different frequencies of light, the distribution of light over imaginary 360° spheres around the bulbs and other factors. In round figures, typical incandescent bulbs are something like 2% efficient and domestic CFLs are currently 7%-8% efficient.

Cost

In addition to the above savings on energy costs, CFLs' average life is between 8 and 15 times that of incandescents. [5] While the purchase price of a CFL is typically 3 to 6 times greater than that of an equivalent incandescent lamp, the savings accrued make the CFL much less expensive in the long run. [6]

Cold weather and dimming

Compact fluorescents may fail to operate at low temperatures. Light output drop at low temperatures, and they may not light at all below zero degrees C (32 degrees F). They also have unacceptably short life when switched on and off frequently. Incandescent bulbs operate well with no loss of brightness at extremely low or high temperatures and can better withstand frequent turning on and off, as in security light applications. Manufacturers of compact fluorescents warn against using ordinary CFLs to replace incandescent bulbs in enclosed fixtures or those which are controlled by dimmers..

Another disadvantage is that dimming of fluorescent lamps requires special lamp ballasts. According to BC Hydro, and Environmental Defense , new dimmable screw-in fluorescent bulbs are now available, however, these models only dim to a certain percentage such as 10 or 20 percent before turning off completely.

Comparison with LED lamps

Whilst CFLs are an important development in energy conservation for most lighting, LED lighting has already filled a few specialist niches like traffic lights and may have the potential to compete with CFLs in the near future. LED lamps have current efficiencies of 30% with higher levels attainable, and a lifetime of around 50,000 hours, but currently are struggling to deliver the required domestic light output while maintaining a reasonable working lifespan.

Colors

A photograph of various lamps 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	kelvin	mired
"Warm white" or "Soft white"	< 2700 K	370 M
"White", "Bright White", or "Medium White"	2900 - 3000 K	333- 345 M
"Cool white"	4000 K	250 M
"Daylight"	> 5000 K	200 M

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 lamps 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
• Blue for phototherapy
• Yellow, for outdoor lighting, because it does not attract insects
• Black light (UV light) for special effects

Black light CFLs, those with UVA generating phosphor, are much more efficient than incandescent black light lamps, since the amount of UV light that the filament of the incandescent lamp produces 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

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."

File:CFL bulb mercury use environment.svg

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

CFLs, like all fluorescent lamps (e.g., long tubular lamps common in offices and kitchens), contain small amounts of mercury 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.

Some manufacturers such as Philips and GE make very low mercury content CFLs. 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". According to the Environmental Protection Agency (EPA), (when coal power is used) the mercury released from powering an incandescent lamp for five years exceeds the total of (a) the mercury released by powering a comparably luminous CFL for the same period and (b) the mercury contained in the lamp. 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.". 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.

How they work

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.

End of life

Both the ballast and the burner (tube) are subject to failure from normal use. A detailed description of the failure modes of fluorescent lamps is given in the Fluorescent lamp article.

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 CFLs.

Many territories do provide recycling facilities for fluorescent lamps. However, many CFLs are crushed in landfills, exposing air and water to mercury vapour.

Design issues

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 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 incandescent tungsten lamps, emit black body radiation.)
• Size: 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.
• Covered performance: To approximate the look of an incandescent lamp, 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, although dimming performance is poor with the quality dimming range restricted to 50-95% light output. Dimmable compact fluorescents tend to retain the same color temperature as they are dimmed, rather than appearing as a warm orange like an incandescent light when dimmed.
• Large deployments of CFLs require specialised electronics with low levels of electronic distortion to avoid disturbing the electricity supply. This is usually not a problem with home use because of the few lamps deployed per site.
• Time to achieve full brightness: Compact fluorescent lamps may provide as little as 50-80% of their rated light output at initial switch on and can take up to three minutes to warm up, and color cast may be slightly different immediately after being turned on. This compares to around 0.1 seconds for incandescent lamps and around 0.01 seconds for LED lamps.). In practice this varies between brands/types. It is more of a problem with older lamps, "Warm (colour) tone" lamps and at low ambient temperatures.
• CFLs do not usually fail suddenly, as incandescent lamps 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 that prevents this.
• Outdoor Use: CFLs that are not designed for outdoor use may perform poorly in cold weather; CFLs are available with cold-weather ballasts, which may be rated to as low as -23 degrees Celsius (-10 F).
• Differences among manufacturers: There are large differences among quality of light, cost, and turn-on time among different manufacturers, even for lamps that appear identical and have the same color temperature.
• CFLs generally get dimmer over their lifetime, so what starts out as an adequate luminosity may become inadequate. In one series of tests by the U.S. Department of Energy for the Energy Star program, one-quarter of tested CFLs no longer met their rated output after 40% of their rated service life.

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 lamp. 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 bathroom or closet).

Efforts to encourage adoption

Due to the potential to reduce electric consumption and hence pollution, various organizations have undertaken measures to encourage the adoption of CFLs, with efforts ranging from publicity to encourage awareness and make CFLs more widely available to direct measures to provide CFLs to the public. Some electric utilities and local governments have subsidized CFLs or provided them free to customers as a means of reducing electric demand (and thereby delaying additional investments in generation). More controversially, some governments are considering stronger measures to encourage adoption of CFLs or even entirely displace incandescents; some proposed efforts involve tax measures, but Australia has announced a plan to phase out the use of incandescent lamps by 2010. Similarly Canada has also committed to phasing out incandescent lamps starting in 2012.

Voluntary measures

Home Depot gave away 1,000,000 CFLs on Earth Day 2007.

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..

In Ottawa, Canada, there is an effort to get every household to change at least one lamp. Project Porchlight has volunteers going door-to-door providing one CFL to every household for free. In other locations in Canada, local utilities regularly undertake "energy audits" to customers to suggest ways to reduce consumption (and reducing investment requirements for the utilities); CFLs are often given away or provided at subsidized prices to raise awareness of the potential savings.

The U.S. Environmental Defense initiated a campaign in June 2006 called Make the Switch to encourage the public to switch from incandescent lamps to compact fluorescent lamps. It asked every household in the U.S. to replace three 60-watt incandescent lamps 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. In the Netherlands, Greenpeace are attempting to mobilize people to Change 1 million light bulbs to CFLs.

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 lamps 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 lamp. To coincide with the launch of this campaign, Yahoo has created a Web site 18seconds.org that will track lamp sales and energy savings nationwide and encourage lamp-switching competition among cities and states.

In South Africa the main electricity supply company Eskom has launched a program to exchange incandescent lamps for CFLs for free. Its aim is to reduce the electrical demand at peak times. [7]

Another website, Onebillionbulbs.com, is behind a campaign to replace one billion incandescent lamps 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.

Recognizing that lower income households are less likely to lay out the significantly greater retail price for compact fluorescent light bulbs, which can cost 5 to 6 times the cost of an incandescent bulb, the site [8] is accepting donations that will be used to give compact fluorescent bulbs to these lower income households.

Government measures

Australia

The Australian federal government plans to phase out the use of incandescent lamps by 2010, apparently the first government to do so in the world.. The Government has not announced any concurrent recycling program for old incandescent lamps. The South Australian government has published an Energy saving calculator in order to help people calculate their individual benefits. However, there is no ban on such lamps yet. Conversion to CFLs will save Australia approximately 800,000 tonnes of greenhouse gas emissions per year. Australia's current yearly output is 564,000,000.

Canada

On 18 April 2007, the Ontario government announced that it was planning to ban incandescent lamps in 2012 to cut the local energy consumption. Following the announcement, the fellow province of Nova Scotia has also pondered a similar ban The territory of Nunavut are planning to ban incandescent lamps in May 2007.

A week later, on the 25 April 2007, the federal government announced plans to ban the sale of incandescent lamps by 2012 all over Canada.

United Kingdom

In the UK, some activists in Britain have lobbied Parliament to tax or ban incandescent lamps, a measure that has generated controversy, and websites like Banthebulb.org have been created in support of the ban; other commentators oppose any proposed ban. The Government itself focuses its efforts to improve household energy efficiency through its establishment and funding of the Energy Saving Trust

Gallery of CFLs

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

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).

See also

• Fluorescent lamp
• Luminous efficacy
• Energy efficiency

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
• 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
• Earth 911 - For fluorescent bulb recycling centers by postal code (US Only)
• Mercury in Compact Fluorescent Lamps - from the National Electrical Manufacturers Association
• Typical Lumen Outputs and Energy Costs for Outdoor Lighting
• Compact Fluorescents: Frequently Asked Questions Australian Greenhouse Office, Dept of the Environment and Water Resources, Australian Government.
• SPECTRA OF FLUORESCENT LIGHT BULBS
• POSSIBLE SAFTY HAZARDS