Compact fluorescent lamp

From Wikipedia, the free encyclopedia Jump to: navigation, search "Low-energy light-bulb" redirects here. For other low-energy bulbs, see Solid-state lighting. HYPERLINK "http://en.wikipedia.org/wiki/File:Energiesparlampe_01_retouched.jpg" \o "Tubular-type compact fluorescent lamp is one of the most popular types among European consumers." Tubular-type compact fluorescent lamp is one of the most popular types among European consumers. A compact fluorescent lamp (CFL), also known as a compact fluorescent light or energy saving light (or less commonly as a compact fluorescent tube [CFT]), is a type of fluorescent lamp. Many CFLs are designed to replace an incandescent lamp and can fit into most existing light fixtures formerly used for incandescents. Compared to general service incandescent lamps giving the same amount of visible light, CFLs generally use less power, have a longer rated life, but a higher purchase price. In the United States, a CFL can save over 30 US$ in electricity costs over the lamp's life time compared to an incandescent lamp and save 2,000 times its own weight in greenhouse gases.[1] Like all fluorescent lamps, CFLs contain mercury, which complicates their disposal. CFLs radiate a different light spectrum from that of incandescent lamps. Improved phosphor formulations have improved the subjective 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.[2] Contents [hide] ​ 1 History ​ 2 Construction o​ 2.1 Parts o​ 2.2 Integrated CFLs o​ 2.3 Non-integrated CFLs o​ 2.4 CFL power sources ​ 3 Health issues ​ 4 Comparison with incandescent lamps o​ 4.1 Lifespan o​ 4.2 Energy efficiency ​ 4.2.1 Efficacy and efficiency o​ 4.3 Cost o​ 4.4 Starting time ​ 5 Comparison with alternative technologies ​ 6 Other CFL technologies ​ 7 Spectrum of light ​ 8 Environmental issues o​ 8.1 Energy savings o​ 8.2 Mercury emissions ​ 8.2.1 Broken and discarded lamps ​ 8.2.2 Mercury poisoning of Chinese factory workers ​ 9 Design and application issues ​ 10 Efforts to encourage adoption o​ 10.1 Labeling programs ​ 11 See also ​ 12 Notes and references ​ 13 External links [edit] History An early compact fluorescent lamp The parent to the modern fluorescent lamp was invented in the late 1890s by Peter Cooper Hewitt.[3] The Cooper Hewitt lamps were used for photographic studios and industries.[3] Edmund Germer, Friedrich Meyer, and Hans Spanner then patented a high pressure vapor lamp in 1927.[3] George Inman later teamed with General Electric to create a practical fluorescent lamp, sold in 1938 and patented in 1941.[3] The modern CFL was invented by Edward E. Hammer, an engineer with General Electric, in response to the 1973 oil crisis. While it met its design goals, it would have cost GE about US$25 million to build new factories to produce them and the invention was shelved.[4] The design was eventually leaked out and copied by others.[4] CFLs have steadily increased in sales volume. [edit] Construction A compact fluorescent lamp used outside of a building. Electronic ballast of a compact fluorescent lamp The most important technical advance has been the replacement of electromagnetic ballasts with electronic ballasts; this has removed most of the flickering and slow starting traditionally associated with fluorescent lighting. There are two types of CFLs: integrated and non-integrated lamps. [edit] Parts There are two main parts in a CFL: the gas-filled tube (also called bulb or burner) and the magnetic or electronic ballast. An electrical current from the ballast flows through the gas (mercury vapour), causing it to emit ultraviolet light. The ultraviolet light then excites a phosphor coating on the inside of the tube. This coating emits visible light. Electronic ballasts contain a small circuit board with rectifiers, a filter capacitor and usually two switching transistors connected as a high-frequency resonant series DC to AC inverter. The resulting high frequency, around 40 kHz or higher, is applied to the lamp tube. Since the resonant converter tends to stabilize lamp current (and light produced) over a range of input voltages, standard CFLs do not respond well in dimming applications and special lamps are required for dimming service. CFLs that flicker when they start have magnetic ballasts; CFLs with electronic ballasts are now much more common. [edit] Integrated CFLs Integrated lamps combine a tube, an electronic ballast and either an Edison screw or bayonet fitting in a single CFL unit. These lamps allow consumers to replace incandescent lamps easily with CFLs. Integrated CFLs work well in many standard incandescent light fixtures, which lowers the cost of CFL conversion. Special 3-way models and dimmable models with standard bases are available for use when those features are needed.[5] [edit] Non-integrated CFLs Non-integrated CFLs have a separate, replaceable bulb and a permanently installed ballast. These ballasts are typically of the magnetic type, and the starter is housed in the base of the replaceable bulb. Since the ballasts are placed in the light fixture they are larger and last longer, compared to the integrated ones. Non-integrated CFL housings can be both more expensive and sophisticated. [edit] CFL power sources CFLs are produced for both alternating current (AC) and direct current (DC) input. DC CFLs are popular for use in recreational vehicles and off-the-grid housing. Some families in developing countries are using DC CFLs (with car batteries and small solar panels and/or wind generators), 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. [edit] Health issues See also: Light sensitivity According to the European Commission Scientific Committee on Emerging and Newly Identified Health Risks (SCENIHR) in 2008, the only property of compact fluorescent lamps that could pose an added health risk is the ultraviolet and blue light emitted by such devices. The worst that can happen is that this radiation could aggravate symptoms in people who already suffer rare skin conditions that make them exceptionally sensitive to light. They also stated that more research is needed to establish whether compact fluorescent lamps constitute any higher risk than incandescent lamps.[6] If individuals are exposed to the light produced by some single-envelope compact fluorescent lamps for long periods of time at distances of less than 20 cm, it could lead to ultraviolet exposures approaching the current workplace limit set to protect workers from skin and retinal damage.[6] The UV received from CFLs is too small to contribute to skin cancer and the use of double-envelope CFL lamps "largely or entirely" mitigates any other risks, they say.[6] [edit] Comparison with incandescent lamps [edit] Lifespan The average rated life of a CFL is between 8 and 15 times that of incandescents.[7] CFLs typically have a rated lifespan of between 6,000 and 15,000 hours, whereas incandescent lamps are usually manufactured to have a lifespan of 750 hours or 1,000 hours.[8][9] Some incandescent bulbs with long rated lifespans of 20,000 hours have reduced light output.[10] The lifetime of any lamp depends on many factors including operating voltage, manufacturing defects, exposure to voltage spikes, mechanical shock, frequency of cycling on and off, lamp orientation and ambient operating temperature, among other factors. The life of a CFL is significantly shorter if it is only turned on for a few minutes at a time: In the case of a 5-minute on/off cycle the lifespan of a CFL can be up to 85% shorter, reducing its lifespan to "close to that of incandescent light bulbs".[11] The US Energy Star program says to leave them on at least 15 minutes at a time to mitigate this problem. CFLs produce less light later in their life than they do at the start. The light output depreciation is exponential, with the fastest losses being soon after the lamp was first used. By the end of their lives, CFLs can be expected to produce 70-80% of their original light output.[12] The response of the human eye to light is logarithmic: Each f-number (or photographic 'f-stop') reduction represents a halving in actual light, but is subjectively quite a small change.[13] A 20-30% reduction over many thousands of hours represents a change of about half an f-stop, which is barely noticeable in everyday life.[14] [edit] Energy efficiency The chart shows the energy usage for different types of light bulbs operating at different light outputs. Points lower on the graph correspond to lower energy use. For a given light output, CFLs use 20 to 33 percent of the power of equivalent incandescent lamps.[15] Since lighting accounted for approximately 9% of household electricity usage in the United States in 2001, widespread use of CFLs could save as much as 7% of total US household usage.[16] If a building's indoor incandescent lamps are replaced by CFLs, the heat produced due to lighting will be reduced. At times when the building requires both heating and lighting, the heating system will make up the heat. If the building requires both illumination and cooling, then CFLs also reduce the load on the cooling system compared to incandescent lamps, resulting in two concurrent savings in electrical power. [edit] Efficacy and efficiency For more details on this topic, see Luminous efficacy. A typical CFL is in the range of 17 to 21% efficient at converting electric power to radiant power based on 60 to 72 lumens per watt source efficacy, and 347 lumens per radiant watt luminous efficacy of radiation for a tri-phosphor spectrum.[17] Because the eye's sensitivity changes with the wavelength, the output of lamps is commonly measured in lumens, a measure that accounts for the effect of the source's spectrum on the eye. The luminous efficacy of CFL sources is typically 60 to 72 lumens per watt, versus 8 to 17 lm/W for incandescent lamps.[18] [edit] Cost While the purchase price of an integrated CFL is typically 3 to 10 times greater than that of an equivalent incandescent lamp, the extended lifetime and lower energy use will more than compensate for the higher initial cost.[19] 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."[20] 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 cost, and reduced labor 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.[21] [edit] Starting time Incandescents reach full brightness a fraction of a second after being switched on. As of 2009[update], CFLs turn on within a second, but may still take time to warm up to full brightness.[22] Some CFLs are marketed as "instant on" and have no noticeable warm-up period,[23] but others can take up to a minute to reach full brightness,[24] or longer in very cold temperatures. Some, that use a mercury amalgam, can take up to three minutes to reach full output.[23] 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. [edit] Comparison with alternative technologies Solid-state lighting has already filled a few specialist niches such as traffic lights and may compete with CFLs for house lighting as well. LED lamps presently have efficiencies of 30% with higher levels attainable. LEDs providing over 150 lm/W have been demonstrated in laboratory tests[25], and lifetimes of around 50,000 hours are typical. The luminous efficacy of available LED fixtures does not typically exceed that of CFLs. Everyday operating temperatures are usually higher than those used to rate the LEDs, their driving circuitry loses some power, and, to reduce costs, LEDs are often driven at their brightest rather than their most efficient point. DOE testing of commercial LED lamps designed to replace incandescent or CFL lamps showed that average efficacy was still about 31 lm/W in 2008 (tested performance ranged from 4 lm/W to 62 lm/W)[26]. As of 2007, LED lamp fixtures also did not deliver the intensity of light output required for domestic uses at a reasonable cost.[27][28][29] General Electric in 2007 announced a high-efficiency incandescent bulb, which was said to ultimately produce the same lumens per watt as fluorescent lamps. GE has since discontinued development. [30] Meanwhile other companies have developed and are selling incandescents that use 70% as much energy as standard incandescents. [31] [edit] Other CFL technologies Another type of fluorescent lamp is the electrodeless lamp, known as a radiofluorescent lamp or fluorescent induction lamp. These lamps have no wire conductors penetrating their envelopes, and instead excite mercury vapor using a radio-frequency oscillator.[32] Currently, this type of light source is struggling with a high cost of production, stability of the products produced in China, establishing an internationally recognized standard and problems with EMC[33] and RFI. Induction lighting is excluded from Energy Star standard for 2007 by the EPA. Some manufacturers make CFL bulbs with an external coating of titanium dioxide.[34][35] It is claimed that the titanium dioxide, when exposed to UV light produced by the CFL, can neutralize odors and kill bacteria, viruses, and mold spores. The Cold Cathode Fluorescent Lamp (CCFL) is one of the newest forms of CFL. CCFLs use electrodes without a filament. The voltage of CCFLs is about 5 times higher than CFLs and the current is about 10 times lower. CCFLs have a diameter of about 3 millimeters. CCFLs were initially used for document scanners and also for backlighting LCD displays, but they are now also manufactured for use as lamps. The efficacy (lumens/watt) is about half that of CFLs. Their advantages are that they are instant-on, like incandescents, they are compatible with timers, photocells and dimmers, and they have a long life of approximately 50,000 hours. CCFLs are a convenient transition technology for those who are not comfortable with the short lag time associated with the initial lighting of CFLs. 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). Some manufacturers add a coating of luminous paint to covered CFL bulbs so that they glow in the dark for a short time after they are turned off. The purpose is to provide lighting in an emergency, such as a blackout following a natural disaster.[36] One manufacturer offers a compact fluorescent lamp with a white LED to provide a dim night-light. A few manufacturers[37][38] make CFL-style bulbs with mogul Edison screw bases intended to replace 250 watt and 400 watt metal halide lamps, claiming a 50% energy reduction; however, these lamps require slight rewiring of the lamp fixtures to bypass the lamp ballast. [edit] Spectrum of light Spectrum of a CFL bulb The light of CFLs is emitted by a mix of phosphors on the inside of the tube, which each emit one color. Modern phosphor designs are a compromise between the shade of the emitted light, energy efficiency, and cost. 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 to achieve a 'white' light with a CRI (color rendering index) of around 80, where 100 represents the appearance of colors under daylight or a blackbody (depending on the correlated color temperature). 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 A blacklight CFL. Color temperature can be indicated in kelvins or mireds (1 million divided by the color temperature in kelvins). Color temperature kelvin mired 'Warm white' or 'Soft white' ≤ 3000 K ≥ 333 M 'White' or 'Bright White' 3500 K 286 M 'Cool white' 4000 K 250 M 'Daylight' ≥ 5000 K ≤ 200 M Color temperature is a quantitative measure. The higher the number in kelvins, 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. Some manufacturers now label their CFLs with a 3 digit code to specify the color rendering index (CRI) and color temperature of the lamp. The first digit represents the CRI measured in tens of percent, while the second two digits represent the color temperature measured in hundreds of kelvins. For example, a CFL with a CRI of 83 and a color temperature of 2700 K would be given a code of 827.[39] 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. Other terms that apply to CFLs: ​ Full Spectrum ​ High Definition [edit] Environmental issues [edit] Energy savings Since fluorescent lamps use less power to supply the same amount of light as an incandescent lamp, they decrease energy consumption and the environmental effects of electric power generation. Where electricity is largely produced from burning fossil fuels, the savings reduces emission of greenhouse gases and other pollutants. While CFLs require more energy in manufacturing than incandescent lamps, this is more than offset by the fact that they last longer and use less energy than equivalent incandescent lamps during their lifespan.[40] [edit] Mercury emissions Main article: Mercury poisoning Coal-Powered Mercury use of compact fluorescent lamp vs. incandescent lamp, if powered by electricity generated completely from coal, though coal accounts for about half of the power production in the United States.This graph does not apply in areas that use hydro, nuclear,solar, wind sources CFLs, like all fluorescent lamps, contain small amounts of mercury[41][42] as vapor inside the glass tubing. Most CFLs contain 3 – 5 mg per bulb, with some brands containing as little as 1 mg.[43][44] 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. In the U.S., lighting manufacturer members of the National Electrical Manufacturers As