Think lumens, not watts
When replacing your existing incandescent bulbs with any of the new energy-efficient varieties, there are a few things to keep in mind. Think of light bulbs in terms of the amount of light they produce (measured in lumens, or "lu") rather than the power they consume (in watts, or "W"). Here are some baseline comparisons.
|To replace a traditional incandescent bulb of...
||... look for a halogen, CFL or LED that outputs about
|| 1600 lumens
|| 1100 lumens
|| 800 lumens
|| 450 lumens
These correlations are approximate and depend to some degree on factors not taken into account, such as the tint of the incandescent bulb(s) in question (for example, a "soft white" bulb will deliver fewer lumens than a "daylight" bulb).
Select your color temperature
With so many options available, you'll be able to achieve the mood you want in any room. The key is color temperature, a measurement (expressed in Kelvins) of the tint a bulb produces. For a warmer tint (rich in reds and yellows), look for a bulb with a Kelvin rating in the low range, between 2700K and 3000K. Higher Kelvin ratings indicate that the bulb produces more light in the blue range of the spectrum, yielding a progressively cooler tint. A bulb rated between 5500K and 6500K will emit light similar to that produced by a typical fluorescent tube. By selecting bulbs in between the extremes, you can create a range of different tones and moods.
Other things to know
As with any traditional light bulb, it's important to be sure the new bulbs are safe and appropriate. Don't forget the basics: Match the size, shape and socket thread of the bulbs you're replacing, and always ensure that the replacement bulbs don't exceed the wattage rating of your fixture.
Information on this page is derived from the U.S. Department of Energy's Office of Energy Efficiency and Renewable Energy (EERE). More information is available at www.energysavers.gov.