Compact fluorescent lamp

from Wikipedia, the free encyclopedia

A compact fluorescent lamp is a small fluorescent lamp . Since the end of 2018, export, import and manufacture within the European Union have been prohibited under the EU Mercury Regulation. One marketing name was energy saving lamp ; this term also includes other energy-saving light sources .

Compact fluorescent lamp ("energy saving lamp") with integrated ballast (EVG) and Edison screw base (E) 27
Compact fluorescent lamp with Edison screw base and coiled tube
Compact fluorescent lamp with integrated starter for operation with an external conventional ballast
Compact fluorescent lamps with Edison screw base and coiled tube with 105 watt, 36 watt and 11 watt power consumption

The tube in which the gas discharge takes place in these lamps is smaller and shorter in diameter than fluorescent lamps , as well as bent, coiled or folded several times in order to save space, hence the compact attachment ~ . With compact fluorescent lamps, a distinction must be made between lamps with and without an integrated ballast . Lamps with an integrated ballast usually have a screw base so that they can be used as a direct replacement for incandescent lamps with Edison threads .

Compact fluorescent tubes have a significantly better environmental balance than conventional incandescent lamps and halogen lamps , but have a significantly greater environmental impact than LED lamps , which are also almost twice as energy-efficient as compact fluorescent tubes.


Philips SL * 18, the first compact fluorescent lamp on the market in 1980
Compact fluorescent lamp from 1984 with conventional ballast and 2004 with electronic ballast

The fluorescent tube was invented over 150 years ago by the German physicist Heinrich Geißler . He filled a glass tube with a gas and applied a voltage. In 1901, Peter Cooper-Hewitt invented the mercury vapor lamp , a discharge lamp filled with mercury that emits blue-green light. Edmund Germer proposed in 1926 to increase the pressure inside the tube and to coat the tube with a fluorescent material that converts the existing ultraviolet radiation into visible light.

On the occasion of the oil price crisis in 1973, engineers at Philips looked for energy-saving alternatives to conventional incandescent lamps. They focused on compact fluorescent lamps, which were made possible by a new, slower aging phosphor coating (diameter only 12 mm). The development culminated in 1976 during the World lighting conference in Eindhoven in the introduction of the prototype SL 1000 ( S elf-ballasted L uminescent with 1000 lumens). The lamp, the service life of which has not yet been specified, had a built-in conventional ballast and, with a luminous flux of 850 lumens, did not achieve the projected value, but only had a power consumption of 18 watts. Due to a length of 21.5 cm and a weight of 750 grams, replacing conventional incandescent lamps was not very practical. The maximum brightness was also only reached after a heating phase of 3 minutes. The U-shaped curved fluorescent lamp was surrounded by a cylindrical glass with a silicon coating on the inside to ensure a more even light emission.

At the end of 1980 the development work led to the presentation of another prototype, the SL * 18 with several improvements: luminous flux 900 lumens, length 16 cm, weight 520 grams, specified service life of 5000 hours. This lamp still had the silicon-coated glass cover.

In 1981 Philips finally launched the first successful compact fluorescent lamp under the name SL * 18 Prismatic . As the name suggests, the glass cover now had a prismatic shape instead of the silicon coating . The lamp had a length of 16.5 cm, a diameter of 7.2 cm, achieved a luminous flux of 900 lumens after 3 minutes with a power consumption of 18 watts (which corresponds to the brightness of an incandescent lamp of 75 watts and thus an energy saving of around 75% meant) and cost around 39 DM in 1983  , which corresponds to around 37 EUR based on today's purchasing power  . In view of the size and weight, it was not possible to use it in all lights .

In the following years, compact fluorescent lamps with integrated ballasts came onto the market from other manufacturers. They were significantly larger and heavier than later models, as they contained a conventional ballast in the lamp base and initially a thick protective glass over the fluorescent tubes. In contrast to compact fluorescent lamps, they visibly flickered and had less good color rendering . The heating phase was many times longer and the light output was significantly lower.

That changed with the introduction of electronic ballasts. In principle, these work more efficiently and increase the efficiency of the fluorescent lamp by 10% due to the high operating frequency of 25 to 50 kHz . The first electronic ballast (EVG) with and for an incandescent lamp socket was published as a patent on April 9, 1984 by Jürg Nigg, Zurich . These energy-saving lamp adapters are still being built today. A life cycle assessment (ETH Zurich) shows that they save more resources than single-use energy-saving lamps with integrated electronic ballasts. According to its own information, the manufacturer Osram brought the first compact fluorescent lamp with an electronic ballast (EVG) and starter electronics integrated into the base in 1985.

While compact fluorescent lamps were initially widespread after the European incandescent lamp ban in 2012, their market share fell sharply in favor of LED lamps , which also contain no mercury. On April 1, 2015, the EU directive banned the manufacture and sale of inefficient lamps that contain mercury and have a light output of less than 80 lumens per watt. Since December 31, 2018, export, import and manufacture within the European Union have been prohibited under the EU Mercury Regulation. Lamps with LED technology had already increasingly displaced the compact fluorescent lamp from the market because they did not have a number of disadvantages (larger size, delayed start, susceptibility to cold, etc.). Currently (2020) there are practically only remnants of compact fluorescent lamps on sale in the trade, with the exception of special versions, e.g. B. with special bases .

Layout and function

X-ray image from three viewing directions (0 °, 45 °, 90 °) through a defective energy-saving lamp. The burned-out filament can be seen on the left.
Electronic ballast in the base of a compact fluorescent lamp with 12 watt power consumption (diameter of the circuit board approx. 32 mm)
Simplified circuit diagram of an integrated ECG

As fluorescent lamps, compact fluorescent lamps count among the mercury vapor low-pressure lamps . To reduce the dimensions , the gas discharge tube is not straight, but rather bent (several times) in a U-shape or designed as a helix . A further reduction in size and a higher luminance are achieved by increasing the internal pressure . The different designs and types of power are usually characterized by the ILCOS lamp designation system and are described in more detail there.

When operated directly from a voltage source, the lamp current of a compact fluorescent lamp would increase due to the negative differential resistance until the lamp is destroyed. In order to limit it, to operate a compact fluorescent lamp, as with other gas discharge lamps , a ballast , which is mostly electronic today, is required. This can either be contained in the lamp or implemented externally. Compact fluorescent lamps with electronic ballast require higher initial investments , but work with a significantly higher degree of efficiency than those with conventional ballast and also have power factor correction filtering . They also more or less reduce the 100  Hz flicker.

An electronically-working ballast heats the lamp start first the cathode by them in the circuit in series to a PTC are resistor. If it has warmed up due to the flow of current, it becomes high-resistance and releases the discharge path for the ballast - the lamp ignites. The pressure build-up, and consequently the evaporation of the mercury, occurs when the device is switched on by preheating the cathodes or heating filaments (directly heated cathodes) and subsequent self-heating. As a result, compact fluorescent lamps do not immediately achieve their full luminosity .

A compact fluorescent lamp (like a fluorescent tube with electronic ballast) contains the following circuit components:

  • a rectifier and
  • a filter capacitor of typically 1 to 4.7 µF to obtain a DC voltage of 325 V for the operation of an electronic circuit,
  • an inverter , which in turn generates an AC voltage of 45 to 60 kHz from this DC voltage and
  • a series resonance circuit (approx. 3 nF + 3 mH) is tuned to its frequency.
  • a gas discharge path parallel to the capacitor and in series with the choke of the series resonance circuit , which uses the voltage increase of the series resonance circuit for ignition.

If savings are made in the dimensioning of the smoothing capacitor and the sieving , this can be noticed by flickering with a frequency of 100 Hz. This frequency is higher than the flicker fusion frequency , but it can cause fatigue and strobing .

Integrated ballast

Compact fluorescent lamps are available as energy-saving lamps with the Edison screw sockets (E14, E27) that are usual for incandescent lamps . The ballast required for operation is located in the base of the lamp. This design allows incandescent lamps to be replaced by compact fluorescent lamps. Since conventional ballasts are significantly larger than electronic ones, electronic ballasts are always used in today's compact fluorescent lamps. Disadvantages of this combination of light source and ballast are the higher price and the ecologically undesirable aspect that the lamp can only be disposed of with the ballast.

The smoothing capacitor (in the circuit diagram it is C2) is the most temperature-sensitive component of the lamp and is therefore located as far away as possible from the fluorescent lamp in the screw base. There is also a fuse to achieve the intrinsic safety of the lamp. All other components are on a circuit board. Thermal problems can occur in narrow and insufficiently cooled luminaires, which reduces the service life of the ballast and thus the lamp.

Circuit description

See the circuit diagram . The AC mains voltage arriving at the screw base is rectified in the bridge rectifier and smoothed with C2. The transistors form a half bridge and, together with the transformer L1 (3 windings on a toroidal core), are a self-oscillating inverter (approx. 45 kHz). The choke L2 is the actual series choke; it is very small due to the high frequency. Together with C3 / C4, it forms a series resonance circuit at start-up which, when the lamp is not ignited, supplies the current flow through the cathode filaments to preheat them as well as the increased ignition voltage. The coupling capacitor C3 ensures the pure AC voltage operation of the choke and lamp. The diac generates a start pulse for the self-oscillating inverter from the charge of C1 (charged via R1). If the inverter is oscillating, D1 prevents recharging / starting by periodically discharging C1 before the diac ignites.

External ballast

In order to separate the ballast (electronic or conventional) from the actual lamp, it is integrated into the luminaire . The designs mentioned below differ in the arrangement of the starter .

Compact fluorescent lamp with integrated starter; The circuit diagram on the left shows the additional reactor (KVG) required for operation on the mains.
Two-pin socket

The starter is integrated in the lamp, in an elongated, rectangular block made of plastic between the two pin contacts on the base of the lamp (mainly base G23). The luminaire into which this lamp is plugged requires a conventional ballast (KVG, a 50 Hz choke coil ) for operation, electronic ballasts (EVG) can lead to starting problems with these lamps. The electrical circuit corresponds to a fluorescent lamp with conventional ballast. The starter is replaced with every change, but this version is relatively inexpensive.

Four-pin socket

Like the electronic or conventional ballast, the starter is integrated into the luminaire. As a result, the base (mainly GX24q) is relatively short and therefore compact. All four hot cathode connections are led out of the fluorescent lamp. It is technically equivalent to large tubular fluorescent lamps.

You can also operate several compact fluorescent lamps on a common external electronic ballast (this reduces investment costs ). External electronic ballasts can be connected to lighting or building management systems such as the Digital Addressable Lighting Interface .


Compact fluorescent lamps sometimes differ considerably in terms of light quality, switching resistance, service life and environmental compatibility . The negative properties of normal fluorescent lamps that do not have an electronic ballast cannot be transferred to compact fluorescent lamps. Compact fluorescent lamps with a conventional ballast are somewhat less efficient.

Since compact fluorescent lamps and LED lamps are used to replace conventional incandescent lamps, there are discussions about the advantages and disadvantages of the different types of lamps. In summary, the Stiftung Warentest assesses its topic package of energy-saving lamps on the negative reports that have been widespread, stating that many allegations are unfounded or only apply to a few products.

Light, color, brightness

Light output

Compact fluorescent lamps use less electrical energy when in operation, as they generate significantly less heat (red).

According to industry standard measurements with 60 to 65 lm / W, (good) compact fluorescent lamps have  a light output that is around four to five times higher than normal incandescent lamps with 10.5 lm / W (40 W) to 13.5 lm / W (100 W). You therefore need 75 to 80 percent less electrical power for the same luminous flux . In the course of their lifetime, the yield decreases steadily in contrast to incandescent lamps, which means that the savings mentioned over the lifetime are lower. In addition, the above-mentioned higher luminous efficacy is based on a measurement method (integrating sphere ), the results of which are not practical in everyday life due to the uneven radiation behavior of compact fluorescent lamps. The luminous efficiency of fluorescent lamps is exceeded many times over by LEDs with up to 300 lm / W.

Light color

A common objection to compact fluorescent lamps is that they emit a “colder” light than incandescent lamps. However, this only applies to lamps with a high color temperature (color tone “neutral white”, “daylight white”), which is more similar to that of sunlight at noon. In Central Europe, “warm tone” lamps are usually preferred for living spaces, with a color temperature of around 2700 K similar to that of incandescent lamps. In addition, the perception of color and warmth is not the same in all people.

For offices, the color temperature and color rendering index depend on the type of activity. Office lighting should meet current standards and recommendations of the professional associations. In the Mediterranean region and in tropical countries, “colder” light colors with higher blue and green components are preferred and lamps with a higher color temperature of, for example, 6500 K are used. If the color temperature is the same, the color rendering of colored objects (for example items of clothing or faces) may be falsified compared to that in sunlight or incandescent lamp light. This is the result of the discontinuous optical spectrum of fluorescent lamps, which deviates from the continuous spectrum of sunlight and incandescent lamp light. This effect is particularly pronounced in lamps with a low color rendering index , which because of the metamerism are not suitable for certain applications (e.g. in a printing shop or in the fashion sector).

A difference in the light color arises when dimming . While with a dimmable compact fluorescent lamp only the brightness is reduced, with a dimmed incandescent lamp the color temperature of the generated light drops significantly because the filament has a lower temperature. In this case, an incandescent lamp produces a redder light (which many people perceive as “warmer” ), while the color temperature of the compact fluorescent lamp remains the same. Compact fluorescent lamps can also be produced in one color (red, yellow, green, blue) and in ultraviolet (UV-A, " black light ") using suitable fluorescent materials. In all of these cases, the efficiency is far greater than that of suitably filtered incandescent lamps whose light is spectrally reduced.

"There are now suitable energy-saving lamps for every luminaire and every socket [...] The number of light colors on offer is also constantly increasing."

- Environment magazine. 2010

Colour reproduction

Since fluorescent lamps, unlike incandescent lamps or daylight, emit a discontinuous spectrum, the colors of objects under the light of these lamps may look slightly different than in sunlight. This effect is particularly disruptive in applications where the color tone has to be assessed, such as in a printing shop. It can be expressed quantitatively using the color rendering index. For compact fluorescent lamps this is typically between 80 and 85. More expensive five-band fluorescent lamps achieve a value of up to 95 with a lower luminous efficacy. Incandescent lamps have a color rendering index of 100. However, the color rendering index is not a percentage, although a higher value is a higher one Displays color accuracy.


Normal compact fluorescent lamps cannot be used with normal dimmers . Only compact fluorescent lamps with specially adapted electronic ballasts vary the lamp current in order to achieve a brightness adjustment of the lamp. If the brightness is lower, the power consumption of the electronic ballast is correspondingly lower. Such compact fluorescent lamps are specially marked and can be operated with ordinary incandescent lamp dimmers that work on the principle of phase control . Touch and wireless dimmers also work with phase control, so that suitable compact fluorescent lamps can be dimmed with them. However, due to the more complicated technology and the small number of pieces, such compact fluorescent lamps are usually more expensive. In addition, compact fluorescent lamps are offered that can be operated in several brightness levels by switching them on and off several times without an external dimmer. Alternatively, the brightness of some compact fluorescent lamps can be adjusted via radio.


In fluorescent lamps with conventional ballasts (CCG), brightness fluctuations occur in a 100 Hz rhythm. During the time when the 50 Hz mains voltage crosses zero, the discharge is extinguished for about 1 to 2.5 ms. The light color also varies somewhat over the period of a half-wave, but this is usually imperceptible. The fluctuations in brightness can lead to the stroboscopic effect , for example when working on moving machines or doing sports in the hall. In the case of incandescent lamps, this flicker is less pronounced because, due to its thermal inertia, the filament also emits light during the zero crossing of the current.

Ideally, fluorescent lamps with electronic ballast (EVG) practically do not flicker because the tube is not operated with the mains frequency of 50 Hz, but with an alternating voltage of around 50,000 Hz. Because of the inertia of the human eye, these frequencies are imperceptible. Due to the afterglow time of the phosphor, the amplitude of the brightness fluctuations is also much smaller than at 100 Hz. In addition, operation with high frequency has the advantage of a higher light yield.

In practice, fluorescent lamps with electronic ballasts can also flicker to a considerable extent, depending on their design. In particular, the electronic ballasts integrated in compact fluorescent lamps are optimized at low cost, for example by omitting or small dimensioning of the smoothing capacitor , so that the rectified supply voltage is still subject to a considerable 100 Hz fluctuation. This modulates the amplitude of the high-frequency tube current and leads to fluctuations in brightness.

Fluctuations in the mains voltage lead to fluctuations in brightness in incandescent lamps. In (compact) fluorescent lamps with high-quality electronic ballasts, this does not occur with voltage fluctuations of up to around 4%.

Markings in trade

Compact fluorescent lamps with different color temperatures in comparison

The light color of a lamp is described by the color temperature in Kelvin . This is a measure of the intensity distribution in the spectrum of the lamp, how the long and short wavelengths are weighted to one another. A higher color temperature means that the light source - as shown in the sketch above - appears bluer. The starting point for this description is the continuous spectrum of a blackbody .

Normal incandescent lamps have a color temperature between 2600 K and 3000 K. Compact fluorescent lamps are available with light colors between 2300 K and 8000 K.

Recordings by hand spectroscope, above: continuous spectrum of a 60 W incandescent lamp, below: discontinuous line spectrum of an equivalent 11 W compact fluorescent lamp. (The light lacks color components, which is why some colors are reproduced differently under the light of this lamp.)

Fluorescent lamps have a non-continuous emission spectrum that differs from a blackbody, so an incandescent lamp can give a different visual impression than a fluorescent lamp with the same color temperature. Whether this is the case depends on the absorption spectrum of the illuminated objects and the quality of the lamp. The latter is approximately measured by the color rendering index. On the packaging, the color temperature and the color rendering index are usually specified in a three-digit code. The first digit stands for the tens of the color rendering index Ra . For fluorescent lamps, the color rendering spectrum ranges from Ra 60 to Ra 98. The higher the value, the easier it is to distinguish colors under the light of the lamp. For light colors below 5000 K, a black body (by definition, a light bulb) has the value 100; for light colors above 5000 K, direct sunlight is given the index 100 as a reference. The next two digits stand for the color temperature in hectokelvin (color temperature in Kelvin divided by 100).

Thus “827” means a color rendering index of Ra 80–89 at a color temperature of 2700 Kelvin. This corresponds to the color temperature of normal incandescent lamp light with a lower but good color rendering index. On the other hand, lamps of the “965” type are used for color patterns; H. Daylight lamps with very good color rendering Ra> 90. Sometimes the color rendering index is given  as a value between 4 and 1A according to DIN 5035. 1B stands for a value between Ra 80 and Ra 89, 1A for a value between Ra 90 and Ra 100.

Compact fluorescent lamps can produce colored light depending on the type of fluorescent material. Ultraviolet lamps are sold under the name black light lamp - a special fluorescent material (light wavelength 350–370 nm) is used here, with the glass having the properties of an ultraviolet filter.



The average lifetimes between 3000 and 15,000 hours specified for compact fluorescent lamps apply under laboratory conditions. In 2006, Stiftung Warentest tested 27 compact fluorescent lamps with regard to their service life. Two of the models only lasted about 4500 hours, 23 lamps over 10,000 hours. In seven of the lamps, the test had to be aborted after 19,000 hours (= over two years) due to time constraints; the service life was above the specified values. In a report by the consumer magazine “Konsument” in 2006, compact fluorescent lamps were tested.

  • In the test cycle of 165 minutes "on" and 165 minutes "off", the cheapest lamps lasted almost 5000 hours, 40% were still lit after 10,000 hours.
  • In the test cycle of 0.5 minutes "on" and 4.5 minutes "off", cheap lamps sometimes only achieved 3500 switching cycles and thus less than 30 hours of lighting time.

Both "Stiftung Warentest" and "Konsument" carried out a further test at the beginning of 2008, which confirmed the old results. Öko-Test finds different results . Of 16 lamp types tested, only six achieved at least a "good" rating in terms of switching resistance (at least 7500 switching cycles with one minute switched on and 5 minutes switched off, i.e. 125 hours of lighting duration), and only six types achieved "(very) good" lighting duration (more than 6000 hours). Many no-name products were also tested (11 of 16).

In addition to the operating time, the switching frequency plays a role in the service life. There are two types of compact fluorescent lamps:

  • Immediate ignition, which is ignited without preheating. These compact fluorescent lamps are very sensitive and age between two and five hours with each ignition process, as the necessary ignition voltage sputters off a lot of electrode material and thus alloyed it with the mercury (service life: ≈ 10,000 h, ≈ 3000 starting processes).
  • Lamps with preheating: the electrodes are preheated for 0.2 to 2 seconds and only then is the ignition of the lamp attempted. The manufacturers promise up to 600,000 switching cycles for these compact fluorescent lamps.

In many areas of application (e.g. in stairwells) one would like to have both properties (fast ignition and long service life). Lifetime specifications of light sources always refer to a "3-hour cycle". This means that the lamps are alternately switched on for 2.75 hours (165 minutes) and then switched off for 15 minutes.


In contrast to clear incandescent lamps or high-pressure discharge lamps, compact fluorescent lamps are not nearly point-shaped light sources, so that a clear incandescent lamp with a freely visible incandescent filament has a different lighting effect than a compact fluorescent lamp with the same light color. When replacing a matt incandescent lamp with a compact fluorescent lamp, the differences are smaller. In particular, compact fluorescent lamps are less dazzling than clear incandescent lamps.

The dimensions of compact fluorescent lamps and incandescent lamps differ. Compact fluorescent lamps are sometimes significantly longer than incandescent lamps, and changing the luminaire may be necessary. In comparison to incandescent lamps, the aesthetic impression is different; no corresponding compact fluorescent lamp is available for certain special incandescent lamps. As with incandescent lamps, there are compact fluorescent lamps with special voltages for solar and camping applications. These can be operated directly on 12 V DC voltage, use the energy much more efficiently than incandescent lamps and light up about five times as long with the same battery charge. These lamps often have an E27 base (so that existing lights can continue to be used) and must not be accidentally connected to the 230 V mains. Due to the elaborate technology of the ballast and the low demand, these lamps are often twice as expensive as a comparable 230 V version and are usually only available on special order. They are offered in warm white (2700 K) and daylight white (6500 K).

Warm-up or preheating phase

A major disadvantage of many compact fluorescent lamps is their temperature-dependent brightness. Depending on the quality and technology used, it takes one to four minutes for 90% of the final brightness to be achieved. During the warm-up phase shortly after switching on, they reach between 50 and 80% of the final brightness. This is unfavorable when lamps are only needed for a short time. Such applications are storage rooms, stairwells or access lights controlled by motion detectors . In addition, they often have a different light color during the start-up phase due to the lower temperature of the phosphor.

High-quality lamps with a preheating function can compensate for the ambient temperature and are very resistant to switching, but start more slowly. After switching on, it takes 0.1 to 2 seconds before the lamp starts to glow because of the preheating phase. Compact fluorescent lamps require briefly (usually less than 0.1 seconds) more power (about 50 times) when they are started than during subsequent operation. The energy consumption during ignition corresponds approximately to that of five seconds in normal operation. This additional consumption is negligible and lower than with incandescent lamps, which also require a higher inrush current because the filament is a typical PTC thermistor .

operating temperatur

Conventional compact fluorescent lamps should ideally be operated at an ambient temperature of 20 to 30 ° C. If the temperature is significantly higher, both light output and service life decrease. The design of the luminaire has a significant influence. If it is closed at the top and has no ventilation openings, the warm air collects in it and increases the heat load on the lamp. Use at low temperatures, especially below freezing point, can also be problematic. On the one hand, the start time described is extended. Special circuits adapted to the temperature are required here. On the other hand, the light output of the lamps decreases. Special compact fluorescent lamps can still be used at temperatures as low as −23 ° C.

EMP resistance

Due to the semiconductor components in the base of a compact fluorescent lamp, this lamp, unlike incandescent lamps, is not EMP- proof; a one-time, short-term, high-energy, broadband electromagnetic compensation process can lead to a defect.

Electromagnetic compatibility

Compact fluorescent lamps with electronic control gear emit high-frequency conducted and non-conducted interference (see electromagnetic compatibility ). These fields are harmless to health, but can interfere with other sensitive devices. The current consumed by compact fluorescent lamps deviates significantly from a sinusoidal curve, so it contains a large number of harmonics . These can influence the voltage quality, especially in island networks.

Noise development

Depending on the quality of the components used in the ballasts of the compact fluorescent lamps, these can generate slight vibrations in the audible frequency spectrum. An unfavorable construction of the lamp socket can make these vibrations audible as hum. 50 Hz and 100 Hz hum can be caused by magnetostriction in the choke. The interference frequency is amplitude-modulated at the actual operating frequency (45,000 Hz would not be audible). By electrostriction harmonics can arise at the rectifier and filter capacitor at 100 Hz. A dimmer with phase angle control causes similar noises, but mostly louder than a compact fluorescent lamp.

environmental Protection

Basically, compact fluorescent lamps have a significantly better environmental balance than conventional light bulbs or halogen lamps despite the higher energy consumption for their production . The environmental balance of all lamp types is largely determined by the usage phase and the electricity mix used; the environmental balance of compact fluorescent lamps during manufacture is low compared to the environmental balance during operation. Even when using an electricity mix of 100% hydropower , compact fluorescent tubes achieve a better environmental balance than incandescent lamps after less than a year of operation. In the case of energy-saving lamps, halving the service life results in only a slightly poorer environmental balance. Due to their mercury content, however, it is important to properly dispose of the fluorescent lamp, even if the main source of mercury emissions is fossil power plants . From an environmental point of view, however, it is much better to use LED lamps , which require even less electrical energy. Due to their mercury content, among other things, the environmental balance of compact fluorescent tubes is on average 12 times worse than that of LEDs.

Energy balance

A compact fluorescent lamp with an average service life of 10,000 hours and a power consumption of 11 W is compared with a 60 W incandescent lamp with a life expectancy of 1000 hours. The energy balance for the compact fluorescent lamp is positive. The production of the light source requires around ten times the energy compared to the production of a conventional filament lamp. However, the energy consumption for the complex disposal process or recycling is not taken into account in most of the calculations.

The production of a compact fluorescent lamp requires around 12 MJ (= 3.33 kWh) of primary energy and is therefore significantly more complex than the production of an incandescent lamp of around 1 MJ. Furthermore, 52 MJ will be spent on selling both lamps. In operation, the above-mentioned compact fluorescent lamp requires around 99 MJ of primary energy in 1000 hours, while the incandescent lamp consumes around 540 MJ in 1000 hours; the efficiency of the provision of electrical energy is assumed to be 40%.
Assuming a service life of 10,000 hours for a high-quality compact fluorescent lamp, this amounts to a total of 1054 MJ compared to 5930 MJ for the 10 incandescent lamps used in the same time. So the saving is 82 percent. If the compact fluorescent lamp did not last longer than an incandescent lamp, there would be savings of 72 percent with 163 MJ compared to 593 MJ.

If, with a value of around 10 percent of the electricity consumption for lighting in an average household, all incandescent lamps are replaced by compact fluorescent lamps, which have 80 percent less electricity than incandescent lamps, this reduces the total electricity consumption of the household by eight percent.

The often cited statement that 95% of the energy consumption of a filament lamp is lost unused is wrong. The heat given off is reflected in the heating / cooling balance, which is why the replacement of compact fluorescent lamps usually results in increased heating requirements. However, electricity heating is questionable both economically and ecologically. The heat gain from filament lamps can be achieved more cost-effectively with most other forms of heating and the generation of electricity itself in Germany, for example, is currently still largely covered by fossil fuels such as lignite, hard coal or natural gas. In rooms cooled with air conditioning, on the other hand, every heat emission leads to an increased overall energy requirement.

CO 2 emissions

When fossil fuels are burned to generate electricity, which dominates in many countries, the amount of the greenhouse gas carbon dioxide (CO 2 ) varies depending on the fuel . Since compact fluorescent lamps consume less electricity than incandescent lamps, their use indirectly reduces the CO 2 emissions associated with lighting . Compact fluorescent lamps save around 490 kWh of electrical energy in 10,000 operating hours compared to ten 60 watt incandescent lamps. Thus, the CO decreased 2 - emissions by 290 kg. This estimate assumed the German electricity mix with CO 2 emissions of 590 g / kWh (value from 2008, more recent figures lower). Originates the current from power plants with lower CO 2 emissions, such as water , wind or nuclear power plants , the less CO is accordingly 2 emits and saved. In addition to CO 2 , the gases sulfur dioxide and nitrogen oxides are emitted when coal is burned . The use of compact fluorescent lamps also reduces these emissions.

Mercury emissions

In the domestic area

Like all fluorescent lamps, the compact fluorescent lamps commercially available to date contain toxic mercury . According to the RoHS directive, a maximum amount of 3.5 mg per lamp applies in the EU . For general lighting purposes with less than 30 watts, a maximum value of 2.5 mg per burning point applies after December 31, 2012 according to Annex III, Section 1a of this guideline. With high-quality lamps, less than 1.5 mg is used or mercury alloys are used to prevent the escape of mercury in the event of a glass break . The exact amount must be stated on the packaging in accordance with EU Regulation (EC) No. 244/2009. The mercury is hermetically sealed and can only escape if the glass breaks. If a lamp breaks in a closed room, the mercury load in the room air can rise to 20 times the standard value of 0.35 µg per cubic meter. This health hazard affects everyone who could come into contact with broken compact fluorescent lamps in the course of garbage disposal and waste separation.

Due to the mercury and the risk of contamination, the following steps are recommended if fluorescent lamps break:

  1. Ventilate well before, during and after cleaning. Everyone should leave the room for 15-30 minutes. Also lead pets out of the room.
  2. Put on rubber gloves to avoid skin contact.
  3. Collect splinters and dust on smooth surfaces with a folded cardboard and wipe with damp paper, on carpets with adhesive tape. A vacuum cleaner should not be used, as its exhaust air can spread the mercury further.
  4. Place all residues and cleaning materials in an airtight jar.
  5. Bring glass to collection point for electronic devices or to the point of sale.

If a lamp breaks while it is lit, more mercury escapes into the air than a cold one, since the proportion of gaseous mercury in the compact fluorescent lamp is higher when it is warm, while in a cold lamp a larger part of the mercury is liquid and adheres in small droplets on the inner walls of the glass. Stiftung Warentest recommends compact fluorescent lamps with amalgam technology and a double envelope as protection against breaking the fluorescent tube, although there seem to be manufacturer-specific differences in terms of resistance to breakage. The amalgam used here is a metallic mercury compound which is solid at room temperature and which only evaporates during operation. If such a lamp breaks when it is cold, the mercury does not escape into the air. However, such lamps take longer to reach their maximum brightness.

In the meantime, completely mercury-free fluorescent lamps have been developed, whose effective light output is 10% higher than that of conventional compact fluorescent lamps and which are also dimmable. Their light color is similar to that of light bulbs. The estimated lifespan is around 27 years.

In the atmosphere

When generating electricity in coal-fired power plants , mercury is released along with other pollutants. In the German electricity mix, around 2008 this was around 0.0147 mg per kilowatt hour of electricity. From this it can be calculated that the additional mercury emission of around 3.6 mg from a 60-watt incandescent lamp after a period of around 5000 hours corresponds to the currently valid maximum amount for compact fluorescent lamps of 5 mg, and therefore a compact fluorescent lamp is better, even if disposed of incorrectly Has a mercury balance. However, if electricity were generated solely by power plants without mercury emissions (e.g. in nuclear and gas power plants , or using renewable energy sources ), even the operation of incandescent lamps would not cause any such emissions. In contrast, if the compact fluorescent lamp is not properly disposed of, up to 3.5 mg of mercury would be released per unit. It also depends on the environmental balance of electricity generation whether ultimately more or less mercury gets into the environment.

Another problem is the degradation of mercury necessary for the production of compact fluorescent lamps . For example, in China , where most European manufacturers manufacture them, old, long-abandoned mines have been reopened; Reportedly to meet growing needs in the EU. The degradation of the toxic heavy metal takes place there mostly under inhumane conditions and without any environmental controls.
Assuming two lamps for every EU inhabitant as an example calculation, this would result in an increase in demand of a few tons of mercury. Some critics doubt the causality mentioned above and argue that around 70 tons of the heavy metal are supposedly required annually for amalgam fillings in the EU.

The recycling of old lamps has so far been inadequate because - even across Europe - the majority of lamps are disposed of in household waste and / or are illegally exported to third world countries. The statements of the source Bulb Fiction cited on this topic were dealt with in a white paper: Energy-saving lamps - compact fluorescent lamps by the ZVEI on May 7, 2012 and the statements in the film were compared with facts. The mercury of those compact fluorescent lamps that are recycled is at least partially disposed of as hazardous waste in Germany due to the lack of economic processes . With the usual treatment processes, the gaseous part is also released into the atmosphere.

Other pollutants

The electronic circuit board and the plastic housing are equipped with flame retardants . These can outgas during operation , which, as with other electronic components, can lead to odor nuisance and health problems. The Federal Environment Agency initially came to the conclusion that the concentrations were negligibly low and that there was no additional health risk. However, outgassing is generally to be expected with new technical devices. The topic of dangers, even when used properly, is addressed in the ZDFzoom film "Toxic Light" by Alexandra Pfeil, which was broadcast on August 8, 2012.

Disposal and recycling

Lamps to be disposed of separately
Energy saving lamp on a wild landfill

Defective compact fluorescent lamps are hazardous waste because they contain mercury and other problematic substances in the glass tube, in the electronics and in the potting material. They must not be thrown into household waste or in the glass container. Proper disposal, separated from household waste or commercial waste similar to household waste, not only serves to protect the environment, but also to protect the health of people who come into contact with the waste. The luminous powder containing mercury is not recycled, but stored in the salt dome, as extraction of the mercury is uneconomical.

Heat development

Since fluorescent tubes develop less heat than incandescent lamps with the same light output, a luminaire with compact fluorescent lamp can emit more light despite the limited lamp output. A luminaire that is designed for incandescent lamps up to 25 watts (which results in around 200 lumens), for example, can be upgraded to 500 lumens with a 10 watt compact fluorescent lamp if there is enough space in the luminaire. However, compact fluorescent lamps are sensitive to heat. In the example, a compact fluorescent lamp with up to 25 W cannot be used without further ado, since the resulting heat could overload the lamp and shorten its service life.

Comparison of effort

In 2008 the Öko-Institut e. V. in cooperation with the Institute for Social-Ecological Research (ISOE) compact fluorescent lamps. The data are based exclusively on surveys of the manufacturers, not on actual tests. Based on this, the table below compares an 11 watt compact fluorescent lamp (572 lumens, 650 lumens as usual in October 2013) with a 60 watt incandescent lamp, which was brighter at the time (710 lumens, the source cites 685 lumens). The values ​​relate to a daily light duration of 3 hours at an electricity price of 22 euro cents per kilowatt hour (as of May 2008). The average service life of a compact fluorescent lamp would result in the use of 10 incandescent lamps instead of 1 compact fluorescent lamp over the period; this period was used to compare the emissions. If 60% of German households were basically equipped with energy-saving lamps, 4.5 million tonnes of carbon dioxide could be saved, an amount that 1.8 million medium-sized cars achieve with a mileage of 15,000 kilometers per year. Compact fluorescent lamps are to be disposed of as hazardous waste because, like all fluorescent lamps, they contain mercury.

Compact fluorescent lamp compared to the incandescent lamp
11 watt compact fluorescent lamp 60 watt incandescent lamp
Electricity costs per year 2.65 euros 14.45 euros
Electricity consumption per year 12.0 kilowatt hours 65.7 kilowatt hours
CO 2 emissions per year 7.8 kg 42.4 kg
Lifespan of a lamp 10,000 hours 1000 hours
CO 2 emissions over 10,000 hours 71.2 kg 387.2 kg
Mercury content in the lamp 2 mg not applicable
Mercury emissions over 10,000 hours with 42% coal-based power generation 3.29 mg 8.86 mg

Potential savings

Interaction with heating and cooling energy

A Canadian study from 2008 shows an interaction between the energy saved and the energy required by heating and air conditioning. Since compact fluorescent lamps emit less heat than incandescent lamps, the need for heating energy increases slightly during the heating season when using compact fluorescent lamps. Conversely, the need for cooling energy (building air conditioning systems) drops minimally during the cooling season when using compact fluorescent lamps.

The general energy saving potential therefore depends on the climate. The calculated cost savings in terms of total energy consumption per household (two-story house with around 210 square meters) can fluctuate very strongly. For example, between 8 dollars a year in St. John's (Newfoundland) (cool climate - lower savings potential, as there is little heating effect from compact fluorescent lamps) and 44  Canadian dollars per year in Los Angeles (warm climate - higher savings potential, as almost no cooling effect is necessary Use of compact fluorescent lamps).

However, it must be noted that the efficiency of power generation and transmission of around 30% is significantly below that of heating systems based on primary energy (such as gas, coal or wood) of around 90%. Heating with incandescent lamps or electric heaters therefore generally uses around three times as much primary energy as operating conventional heaters. Accordingly, the price of heating oil or gas per kWh is significantly lower than that of electricity.

Relation to the light duration

The financial savings potential of compact fluorescent lamps through electricity price gains is only achieved after the lamp has been in use for a certain period of time compared to the higher purchase price. As a result of a study by finanztest , the service life is influenced by the manufacturing and operating conditions; some models only lasted around 4500 hours, while with others the test had to be stopped after 19,000 hours for reasons of time. Furthermore, the savings potential of lamps with a long service life turns out to be significantly greater if a lamp change is complex and associated with personnel costs. In particular, compact fluorescent lamps can be connected to light management systems that report a lamp failure.

Electromagnetic environmental compatibility

Compact fluorescent lamps with electronic ballast (like many other electrical devices) generate electromagnetic interference, which is summarized under the term electromagnetic environmental compatibility . These electromagnetic emissions, also known colloquially and pejoratively as electrosmog , mainly consist of the high-frequency magnetic field. In contrast, the magnetic fields emanating from incandescent lamps have a lower frequency, but are correspondingly stronger because of the higher current. In the case of low-voltage halogen lamps, significantly stronger low-frequency magnetic fields are generated, and when using switched-mode power supplies, high-frequency magnetic fields similar to those of compact fluorescent lamps are generated.

A comparison of these electromagnetic emissions is hardly possible because it is unclear whether a greater intensity or a higher frequency is more important, or whether these emissions are relevant to health at all. In terms of the field strengths measured, compact fluorescent lamps are within the range of values ​​from other electrical devices.

"The use of compact energy-saving lamps for general lighting purposes in the household is not questionable in terms of radiation protection."

- Federal Office for Radiation Protection


  • Peter Berz, Helmut Höge, Markus Krajewski (eds.): The light bulb book. 2nd edition, Braunmüller, Vienna 2011, ISBN 978-3-99100-038-9 .

Web links

Wiktionary: Energy saving lamp  - explanations of meanings, word origins, synonyms, translations
Commons : Compact Fluorescent Light  - Collection of pictures, videos and audio files

References and comments

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