Compact fluorescent lamps (“energy savers”) belong to the group of low pressure discharge lamps. They were specifically designed to directly replace incandescent lamps as they fit into the same space as the standard light bulbs and can be fixed into standard sockets. They use up to 5 times less electricity than standard incandescent lamps (max light efficacy: 65 lm/W) and their rated lifespan is between 5 to 15 years. CFL lamps were introduced in 1985, but have been developed further since then in terms of light quality, durability and substitutability. CFL lamps consist of a bulb, an electronic ballast (integrated or non-integrated) and either screw or bayonet fitting. They are produced both for AC and DC input.
Fluorescent tubes are the workhorses in office and industrial lighting. As in the case of the CFL lamps they generate UV-light through a gas discharge (using a small amount of mercury – less than 5 mg) which then transforms to visible radiation by the use of fluorescent powders, which are coated inside the bulb or tube.
The necessary electron emission is produced by emitter coated tungsten coils. The emitter material consists of a mixture of alkaline earth oxides.
Use of high quality fluorescent lamps (tri-phosphor lamp) with efficacies of up to 100 lm/W can save 70% energy in combination with electronic control gear.