What Are CFL Bulbs? Everything to Know

Fluorescent lights, the staple of school gyms and grocery stores, aren’t exactly known for their appeal. The long, skinny tubes have cheaply illuminated communal spaces and retail establishments for nearly 100 years, but if you have them in your home, it’s probably in the garage or basement.

Compact fluorescent lamps (CFL), which combine the energy efficiency of fluorescent tubes and the size of a regular light bulb, bridged the gap between utility and decor when they were invented in the 1970s. “The effort to make a compact fluorescent lamp was driven by the need to have small light bulbs that were more efficient than incandescent bulbs,” said Terry McGowan, the director of engineering at the American Lighting Association.

Below, McGowan and Dara Greaney, CEO of LEDLightExpert.com, explain what CFL bulbs are and how they differ from incandescents (the classic glass globes with a filament inside) and light-emitting diodes (LED), which are poised to put both CFLs and incandescents out of business.

What Is a CFL Bulb?

Compact fluorescent lamps (aka bulbs) are just smaller versions of the long fluorescent tubes you see in retail stores and warehouses. (Lighting experts and electricians often say “lamps” instead of “light bulbs,” but you can think of them as the same thing.) “It’s a way to make a fluorescent lamp look more like an incandescent lamp in size,” McGowan says. The long tube has just been shrunk down, often to a spiral or U-bend, so the CFL fits in a regular light socket.

Fluorescent lamps, including CFLs, are filled with gas, which along with a tiny bit of mercury, conducts electricity and produces ultraviolet (UV) light. The invisible UV is converted to visible light by a coating on the inside of the tube. Another distinguishing feature of CFLs is the ballast, which controls the electricity flow through the bulb. In regular fluorescent tube lighting, the ballast is in the light fixture housing. In most CFLs, it’s been moved to the base of the light bulb itself.

When choosing a CFL, look for the lumen rating, not the watts. Watts are a measure of energy, while lumens indicate the light output. Because CFLs use less energy than incandescents, the watts aren’t comparable. Check the package for lumens and wattage equivalents.

Types of CFL Bulbs

Early CFLs were simple affairs, but today’s CFLs give you options:

• Integrated ballast. This is the standard CFL with the coil or tube sitting atop the ballast in the base.
• Non-integrated ballast. McGowan says the lack of an integral ballast makes these lighter and cheaper. You need a fixture with a ballast, though.
• Dimmable, non-dimmable and three-position. The tech’s gotten better, but McGowan says dimming fluorescent lamps can be unsatisfactory due to the expensive circuitry required. Buy bulbs specified as dimmable for best results.
• Base type. CFLs come in screw bases, pin or twist-and-lock bases, push-in and other configurations.

CFL vs. LED Bulbs

Light-emitting diodes are a “solid-state” technology: There’s no gas and no tube, McGowan says. Diodes are little chips made of metal and metal alloys, painted with a coating that lights up when electrified. It’s similar to the coating in CFL bulbs, but that’s where the technical comparisons end. “It’s an entirely different way of creating light,” Greaney says.

There are similarities. They each use a lot less energy than incandescents. They come in multiple colors, and have improved lifespans over incandescents. Expect CFLs to last about 6,000 to 15,000 hours, McGowan says. The rated life of LEDs can reach 25,000 hours. Costs have come down on LEDs but they still cost a bit more than CFLs, Greaney says.

CFL vs. Incandescent Bulbs

Incandescent bulbs produce light by generating heat. Electricity is forced through a thin wire called a filament, which heats up and glows brightly. Unfortunately, most of the energy the incandescent consumes is lost to heat. How much energy are we talking? Nearly all of it, about 90%, according to the Department of Energy (DOE).

CFLs also lose energy to heat, but they produce more light per watt of power, so they’re more efficient. McGowan says you get 50–70 lumens per watt, but just 10 lumens per watt for incandescents of similar light output. Another perk? They last a lot longer. McGowan says incandescents top out at around 1000 hours, compared to the 6,000-15,000 hours of CFLs.

Are CFL Bulbs Being Discontinued?

Eventually, CFLs will be discontinued. Current federal energy efficiency standards require light bulbs sold in the U.S. to produce 45 lumens per watt. McGowan expects that to change, however. The DOE will soon raise that standard to 100 lumens per watt, which will knock CFLs and their 50–70 lumens per watt right off the shelves. “That’s likely to happen over the next 1–2 years,” McGowan says. “There are a few carve-outs for industrial applications, but even those are few and going away,” Greaney says.

But expect overlap as technology develops. “It is unlikely that all types of fluorescent, or even incandescent, lamps will disappear since there are certain applications where LEDs don’t work well,” McGowan says. “A good example is an oven light.” Fluorescent lamps and LEDs struggle in the heat, so McGowan says “incandescent oven lamps are likely to be around for a while.”

What Hazards Are Associated With CFL Bulbs?

Mercury is a known hazard of CFL bulbs. “There is a small drop of mercury in every fluorescent lamp,” McGowan says. Mercury is a metallic chemical element (and neurotoxin) that’s used inside the CFL to conduct electricity. Works great, and it’s generally safe as long as the lamp doesn’t break. This is why it’s important to dispose of CFLs properly to prevent contaminating the air, soil and groundwater.

How To Dispose of Old CFL Bulbs

Dispose of old CFL bulbs by recycling them. This is the only safe way of disposing of CFLs since tossing them in the garbage will break the glass, releasing the mercury within them. Recycling CFLs also allows the electrical ballast and other components and materials to be recovered: Nearly every part of a CFL can be recycled and reused, according to the U.S. Environmental Protection Agency (EPA).

Where to Recycle Old CFL Bulbs

Many municipalities will accept your old CFLs, but you likely have to drop them off at your city’s recycling or hazardous waste center. (Sanitation workers who pick up your recycling don’t have a good way to avoid breaking the glass.) Home improvement centers also take them.

The EPA says the best way to find local recycling options is to visit Search.Earth911, a comprehensive database of recycling centers. Six states currently ban landfill disposal of CFLs and fluorescent tubes: California, Maine, Massachusetts, New Hampshire, Vermont and Washington.

What Is the Best Type of Light Bulb for Your Home?

For energy efficiency, light output and versatility, the experts give LEDs the nod.

“Good LEDs give the best light,” Greaney says. They can even be “warm,” a concern that often crops up when debating the switch to LEDs. Labels on LEDs tell you what kind of light the LED gives off, including the temperature. For best color, get “a good CRI [Color Rendering Index] above 90 for indoors, or above 70 for outdoors, and you’ll get a great light,” according to Greaney.

About the Experts

Terry McGowan has spent his entire career in the lighting industry, starting at GE Lighting right out of college, and running his own lighting design business. He is currently the director of engineering at the American Lighting Association.

Dara Greaney is a lighting expert and the CEO of e-commerce retailer LEDLightExpert.com, where he focuses on LED technology and fixture design.

Sources

• EPA: Recycling and Disposal of CFLs and Other Bulbs that Contain Mercury
• DOE: LED Lighting
• Energystar.gov: Learn about CFLs