Compact Fluorescent Lamp (CFL), also known as a compact fluorescent light bulb, is a type of fluorescent tube light wound or bent to look like a filament bulb, so that it can fit in the existing light fixtures that were formerly used for incandescents, since nowadays CFLs are fast replacing incandescents. Compared to Incandescent lamps, CFLs are energy saving bulbs as they use much less energy and are more efficient.







  
POSITIVES-

· Efficiency: They give out 60 lumens per watt against the 12-14 lumens per watt of incandescents.

· Heat: Since they are more efficient than incandescents, CFLs don't produce as much heat.

· Wattage range: CFLs are available in 30 different wattages, starting from 3watts to 80watts. Some manufacturers have manufactured CFLs in even higher wattages.

· Colour temperature range: CFLs are available in a wide range of colour temperatures from 2700K (warm light) to 5400K (close to daylight)

·  Life: CFLs typically have a rated lifespan of between 6,000 and 15,000 hours. However, the life of a CFL is significantly shorter if it is only turned on for a few minutes at a time.
GREEN CFL:
Because of all these advantages, CFLs are presently the favourite of environmentalists and governments. Fidel Castro, in 2005 was the first to ban the use of incandescent bulbs in favour of CFLs to reduce Cuba's enormous fuel import bill. Britain and Australia already have legislation aimed at phasing out incandescents in favour of CFLs. The US and EU are likely to follow soon. In India, CFLs are being encouraged but the significantly higher cost means that the incandescent bulbs cannot be banned yet.


NEGATIVES-

· Light output: CFLs produce less light later in their life than they do at the start. By the end of their lives, CFLs can be expected to produce 70-80% of their original light output.

·Time to light up: CFLs take a perceptible time to achieve full brightness, and can take much longer in very cold temperatures.

·  Cost: The cost of an integrated CFL is typically 3 to 10 times greater than that of an equivalent incandescent lamp. However, the extended lifetime and lower energy use will compensate for the higher initial cost.

·  Colour rendering: CFLs don't have quite the same colour rendering ability that incandescent bulbs do.

·Dimming: Dimming of lights requires the use of expensive dimmable ballasts.

·Disposal: CFLs contain mercury and have to be disposed off carefully. They can't simply be tossed into a garbage bin. In the US and EU there are strict guidelines for disposal of CFLs.

· Shape: CFLs have strange shapes and don't look very elegant, though there have been some cosmetic improvements lately. They are difficult to manage optically because of their shape.


Considering these disadvantages, and the complexity in the construction and disposal of a CFL there is some debate about how correct the decision of some governments has been, to ban incandescents and replace them with CFLs.


COMPARING A CFL WITH AN INCANDESCENT BULB -

However, in energy terms- the amount of energy consumed by a CFL is way lower than that consumed by an Incandescent Lamp. Researchers at the Technical University in Denmark calculated that:
The total lifetime energy input of a 13W, CFL, over its rated lifetime of 6000 hours is 89.2kWh. By contrast, for the equivalent lifetime and equivalent light output, it would require 36 Incandescent bulbs, each burning its full lifetime of 1000 hours, which means the total lifetime energy input of the incandescent bulb works out to 2170.44kWh.
So, in a greener world, CFL's defenitely have an edge over incandescents.

A CFL is basically a FTL (Fluorescent Tube Light), wound and bent to look like an incandescent bulb, so that it can replace the bulb and fit into the existing incandescent light fixtures.