How to Make the Best Choice
First, choose a lamp that meets your requirements for shape, light output, and configuration. Then, consider the following:

Choose a lamp with the appropriate color quality.The correlated color temperature (CCT) of a CFL is a measure of the warmth of its appearance. CFL products offer CCT ratings in the range of 2,700 to 6,000 K, compared to 2,700 to 3,000 K for incandescent products. Designers looking to match the warmth of an incandescent light should specify CFLs with CCTs in the 2,700 to 3,000 K range. Use higher ratings when looking for a cool quality to the light. Also, because light from products with the same CCT but from different manufacturers may look different, using lamps from a single manufacturer in a large installation will help to ensure that all CFLs installed produce the same color effect.

Lighting manufacturers also use another color metric, the color rendering index (CRI), to quantify the color quality of a light source at a given color temperature. The more accurately a source renders a sample of eight standard colors relative to a reference source, the higher the CRI (measured on a scale of 0 to 100). Incandescent bulbs typically boast CRIs greater than 95, while most CFLs are in the 82 to 88 range.

Pick a lamp suited to the temperature conditions in which it will operate. If you're going to be installing CFLs in a base-down position or in areas where they will experience temperature extremes (as in poorly vented enclosed fixtures, where heat can build up, or in outdoor applications in cold climates), look for products that specifically state that the CFL provides stable light output over a broad range of temperatures and in various positions.

Make sure that the lamps you chose will not have a negative impact on power quality. Using CFLs in a home will not affect power quality appreciably, but their use in significant quantities in a large facility can have an impact. In those cases, look for products with low (below 30 percent) total harmonic distortion (THD) and power factors greater than 0.9. CFL manufacturers often state that their product has a high power factor, meaning that its power factor is greater than 0.9, rather than specifying a specific number.

Select a lamp that meets Energy Star requirements. Manufacturers test their products against these guidelines, and the Energy Star Web site spells out the requirements and lists all qualifying products. From an energy and environmental perspective, products that meet Energy Star requirements will perform as stated.

CFL lamps are best suited to locations where they will remain on for extended periods. Switching on a CFL for short periods, particularly those that start instantly, reduces the expected life of the device. This may defeat the energy/cost saving purpose of the CFL. In such cases, EG automatic lighting and residential toilet/bathroom areas, it may be preferable to use incandescent lamps.

Back to Lighting	Flourescent Lamps
Halogen Lamps	Incandescent Lamps
Compact Flourescent Lamps	Back to Tutorials