The energy saving lightbulbs you are referring to are called compact fluorescent lamps/lightbulbs (CFLs). When shopping for CFLs, look for an electronic ballast, hours, lumens, Color Rendering Index (CRI), temperature, and of course, price.
There are two basic types: the all-in-one version and the separate glass tube and ballast version. For someone starting out, the all-in-one version is the easiest to purchase (and is an electronic ballast). Both versions have a threaded base similar to the incandescent bulb which allows for easy retrofitting.
The hours listed on the box will tell you how long the product will last. CFLs can have a service life of up to 10,000 hours (roughly equivalent to 10 years.)
Also, check the box for the lumens, which is required to be posted on the box. Lumens refers to the amount of light output. This number allows you to compare incandescents with fluorescents. Remember, wattage is a measurement of energy used (thus, how much you are paying on your utility bill) and should NOT be used to compare perceived brightness of CFLs and incandescent lightbulbs.
The CRI is on a scale of 1-100 with 100 being the most desirable light. It compares the color of items under the artificial light you are using to the color of the object if you were looking at it under natural sunlight. Look for products with a CRI of 80 or above. This two-digit number helps to ensure that your clothes match when you get to work!
Temperature, measured in kelvin (K), indicates how warm (orange/yellow/red) or cold (blues) the light appears. The lower the number, the warmer the light. Sometimes, the temperature will only appear as the words "warm white" or "cool white" rather than 3000K and 5000K respectively.
Some other things to consider include: the temperature in the area they will be used, whether they will be dimmed, and whether they will be located in a moist location.
Don't forget to look for the ENERGY STAR® logo! For more information go to the ENERGY STAR Web site - click on "lighting" for more information on CFLs.
