Buy the right Compact Fluorescent Blub.

Compact fluorescent light bulbs, also known as CFLs, are an energy-efficient alternative to conventional incandescent bulbs. In an incandescent bulb, electric current heats a thin filament to the point that it glows. This design produces a warm, soft light, but the bulb loses most of its energy in the form of heat. In CFLs, electric current energizes argon and mercury vapor, which excites a glowing phosphor coating inside the bulb. This design loses very little energy to heat, which means it consumes much less power than an equivalent incandescent bulb.

CFL bulbs generally cost slightly more than incandescent bulbs, but they can pay for themselves in power bill savings. There is no industry standard for measuring energy efficiency, so energy savings ratings will vary from manufacturer to manufacturer. In general, a CFL will use around 75% less electricity than an incandescent bulb with the same light output, while lasting about 10 times longer. Additionally, since CFLs produce less heat, they can help you save on cooling costs.

CFLs come in a range of shapes, sizes, color temperatures, and brightness levels, making it simple to replace most incandescent bulbs with an energy-efficient CFL alternative. While the first generation of CFLs had a characteristic blue tint, newer designs do a good job recreating the warm glow of incandescent bulbs. This buying guide will explain the available CFL options, so you can feel confident you’re selecting the light bulbs that will work best for you.

Bulb Shape Like incandescent bulbs, CFLs come in a variety of shapes, suited to different tasks and light fixtures. Common CFL bulb shapes include:

Spiral Bulb – A basic CFL design with visible fluorescent tubes arranged in a spiral. Spiral bulbs, also known as twister bulbs, do an excellent job providing even light distribution and are ideal for lamps and light fixtures that hide the bulb behind a shade or covering.

A-Line Bulb – A bulb with a rounded cover that has the same basic appearance as a standard incandescent bulb. A-line bulbs are a good option if you have a light fixture that doesn’t conceal the bulb or a lamp with a shade that attaches directly to the bulb.

Globe Bulb – A sphere-shaped bulb, commonly used in bathroom light vanities and pendant lights.

Indoor Reflector Bulb – A bulb that provides directional light. Indoor reflectors are used in recessed lighting, track lighting, and some ceiling fans.

Parabolic Aluminized Reflectors (PAR) – A durable bulb used for outdoor flood lights and spot lights.

Triple Tube Bulb – A compact bulb with visible fluorescent tubes. Triple tube bulbs have high light output but take up very little space, making them a good choice for reading lamps.

Post Bulb – A durable bulb designed for outdoor light fixtures.

Bulb Base Type  As with incandescent bulbs, it’s essential when you’re shopping for CFLs to determine what bulb base size you need. If you’re going to the store, it’s a good idea to bring the bulb you’re replacing along with you, so you can match the base sizes. There are five standard base sizes for CFLs:

• Miniature Candelabra – A small bulb base, frequently used in chandeliers
• Candelabra – A slightly larger bulb base, used in chandeliers, light sconces and other small fixtures
• Intermediate – A bulb base between the candelabra and medium sizes, commonly used in ceiling fans
• Medium – The bulb base design for standard light bulbs, used in most lamps and overhead light fixtures
• GU24 – A two-pin base that fits fixtures with a corresponding GU24 socket. GU24 is an energy-efficient system, designed to replace the conventional, screw-type socket and base design

Safety and Recycling 
CFLs tubes contain a small amount of mercury, which is a toxic metal. On average, there are only 4 milligrams of mercury in a CFL bulb—a fraction of what you would find in a standard mercury thermometer or wristwatch battery. As long as the bulb is intact, the mercury is safely contained, but it’s important to avoid direct contact with a broken bulb. If you break a CFL, you should air out the room for 15 minutes. Then approach the cleanup carefully, following the Environmental Protection Agency’s recommended procedure, available at www.epa.gov/mercury/spills/.

Because of the mercury content, the EPA recommends consumers bring old CFLs to qualified recyclers, rather than disposing of them in trash cans or curbside recycling bins. Contact your local solid waste agency or visit www.epa.gov/bulbrecyling for guidelines on proper disposal in your area. You can bring old CFLs to The Home Depot for free recycling. Visit the Eco Options website to learn more.