How our high-tech lightbulb tests identify the best bulbs

LEDs and CFLs use about 75 percent less energy than standard incandescent bulbs, but that won't matter much if the lightbulbs are dim or give off a weird color. To find CFLs and LEDs that outshine the rest, our experts head straight to the integrating sphere in our lightbulb lab. That's how we know that an EcoSmart LED from Home Depot is the best replacement for a 60-watt incandescent that we've tested.

We place one lightbulb at a time inside the big hollow sphere to determine the bulb's brightness while monitoring its energy use and determining whether the light color is warm or cool. The sphere also shows us how accurately a bulb reveals the colors of objects. "The integrating sphere prevents light from other sources from interfering and captures all the light generated from the bulb," says John Banta, an engineer for Consumer Reports. Put another way, the integrating sphere is very cool.

The sphere sends data to our computers and the engineers analyze it. Meanwhile in a lab down the hall racks and racks of CFLs and LEDs cycle on and off, and after 3,000 hours they're put back in the sphere to learn how regular use affects their performance. Then it's on to more and more testing as we work to find out how LEDs, which have a very long claimed life, perform at 12,000 hours.

Our latest lightbulb Ratings are based on 3,000 hours of testing and show that LEDs outshine CFLs. In fact, a 60-watt replacement EcoSmart CFL from Home Depot scored the lowest of that group.

Some LEDs earned near perfect scores, but not all are good and they can be expensive. The good news is LED prices are dropping. We just spotted a top-scoring Philips 60-watt replacement LED for $15 at a nearby Home Depot. That's $10 less than a month ago. And our lightbulb tests show that there are plenty of fine, inexpensive CFLs to choose from. Before you shop, check our Ratings to find the best bulbs for your sockets.

—Kimberly Janeway