December 21 2007

The Best Compact Fluorescent Light Bulbs

Can the new breed of energy-saving fluorescents hold their own against incandescents? Popular Mechanics ran seven bulbs through their optical course to find out.

The compact fluorescent light bulb revolution nearly occurred back in the early 1990s. When CFLs first hit the market in force, consumers bought them in large numbers ? but they hated them. The bulbs were too big for many fixtures, expensive (up to $25 each) and they threw a dim, antiseptic light that paled next to the warmth of good old-fashioned incandescent bulbs.
When it comes to illuminating your home, brightness isn?t everything. Can CFLs match the light quality of the energy-wasting incandescents we know and love?
Popular Mechanics designed a test pitting seven common CFLs against a 75-watt incandescent bulb. To gather objective data, we used a Konica Minolta CL-200 chroma meter to measure color temperature and brightness, and a Watts up? Pro ammeter to track power consumption. Our subjective data came from a double-blind test with three PM staffers and Jesse Smith, a lighting expert from Parsons The New School for Design, in Manhattan. We put our participants in a color-neutral room and asked them to examine colorful objects, faces and reading material, then rate the bulbs? performance.
The results surprised us. Even though the incandescent bulb measured slightly brighter than the equivalent CFLs, our subjects didn?t see any dramatic difference in brightness. And here was the real shocker: When it came to the overall quality of the light, all the CFLs scored higher than our incandescent control bulb. In other words, the new fluorescent bulbs aren?t just better for both your wallet and the environment, they produce better light.

CFL BACKGROUND

Color temperature: The lower the color temperature, the warmer the light. Warmness (red) or coolness (blue) can be measured in degrees Kelvin by a chroma meter. We observed a temperature of about 2700 K for soft white bulbs, whereas "daylight" bulbs measured around 3400 K ? real noontime sunlight ranges from 5000 K to 6500 K.

Lumens vs. lux: Manufacturers use a complex process to measure lumens, the total quantity of light emitted by a bulb. We used a light and chroma meter to measure lux, the light intensity a bulb shines on a surface. Our observed results in lux generally tracked with manufacturers? lumen ratings.

Watts and efficiency: Our ammeter?s CFL wattage results were all within 3 watts of manufacturer ratings ? but all CFLs use about 70 percent less electricity than incandescent bulbs. The average U.S. household has 45 light bulbs ? replacing that number of 75-watt incandescent bulbs with CFLs would save $180 per year.

Phosphor: This chemical compound lines the inside of CFL tubing. When excited, it converts ultraviolet radiation into visible light. The chemical composition of the phosphor determines the color temperature of the light emitted by the bulb.

Mercury: According to the EPA, CFLs contain an average of 5 milligrams of mercury, which increases the bulb?s efficiency. But that also means you can?t just trash them?CFLs must be properly recycled. Visit Energy Star or Earth 911 for disposal instructions.

Beyond Fluorescent with LEDs: Light emitting diodes (LEDs) are tiny yet powerful sources of light that are even more energy efficient than CFLs. Manufacturing LEDs that produce light equivalent to a 60-watt bulb is expensive, however. One bulb can cost as much as $75.

For more information please visit the

Popular Mechanics website.

December 21st, 2007 at 4:04 PM. Posted in Products + Technology. Share this post.