History

• General Electric developed the basic technology for fluorescent lighting in the 1930s, but it wasn't until the 1970s that fluorescent lighting made advances that allowed the bulbs to be in a compact form, able to replace standard incandescent bulbs. Philips introduced the first commercially available CFL in 1980.
  
  

How It Works

• In an incandescent bulb, electric current passes through a high resistance metal wire called a filament, which then begins to glow, and give off both light and heat. In a CFL bulb, the electric current goes through a tube containing argon gas and mercury. This makes ultraviolet light that acts on a phosphor coating on the inside of the tube to give off visible light. One of the reasons this is significantly more efficient is that CFL bulbs produce very little heat, which is wasted energy in an incandescent bulb.
  
  

Savings

• The typical CFL bulb uses 75 percent less energy than its incandescent equivalent, and lasts 10 times longer. It will pay for itself in about six months. In 2010, the federal government's Energy Star program estimated that if every home in the U.S. replaced the bulb in one fixture with a CFL the nation would save enough energy to light 3 million homes for a year, and prevent 9 billion pounds of greenhouse gas emissions annually.
  
  

Types

• The market has a number of different styles of CFL bulbs, including spiral lamps, globe shapes, candelabra bulbs and even styles that look indistinguishable from a traditional bulb. CFLs are also available in different colors from a warmer, yellower light, to a bluer, daylight type. The color is indicated by the K number on the packaging--the lower the K number, the more yellow the light.
  
  

Drawbacks

• Not all CFLs are dimmable, so a dimmable fixture will need a special bulb. They are most efficient, and last longest in fixtures which remain on for more than 15 minutes at a time, so they are not suitable for places like a closet where they are turned on and off quickly. CFLs contain mercury, so they must be disposed of with care and the disposal must follow special procedures.