Have you wondered what leaving the porch light on costs, or if those newfangled high-tech bulbs really save money? As electric rates soar, lighting choices become more important and by replacing regular bulbs with energy-efficient bulbs, you can save on your bill while conserving energy.

By law, packaging must include information to help you select the most energy-efficient bulbs for your needs. Let’s throw some light on your choices.

Incandescent bulbs are the pear-shaped cuties that usually light everything from porches to nightlights. Incandescents produce light by heating a filament until it glows white hot. Ninety percent of the electricity used by incandescent bulbs is lost as heat. These bulbs typically last for 750-1,000 hours, three hours a day for a year.

Incandescent spotlight and floodlights. The reflective coating on these bulbs directs and focuses light. Often used in recessed ceiling fixtures or outdoors, they last about 2,000 hours.

Tungsten-halogen incandescent bulbs or halogen bulbs. These contain a capsule of halogen gas, which emits a bright white light. Halogens produce more light, use less energy, and last longer than incandescents of the same wattage, but they cost more to buy. They last from 2,000 to 3,000 hours, about two to three years.

General service fluorescent bulbs. These are more efficient than incandescent bulbs because they produce light without heat. They are the long or U-shaped tubes used in office buildings and stores and last from 10,000 to 20,000 hours -10 to 20 times longer than incandescents.

Compact fluorescent bulbs use one-fourth the energy of incandescents to provide as much light. If you replace a 60-watt incandescent bulb with a 15-watt compact fluorescent bulb, you will get the same amount of light.

They are effective and efficient replacements and last about 10,000 hours or 10 to 13 times longer than incandescents.

Energy-efficient bulbs cost more to buy than incandescents but efficiency and longer life offset their higher purchase price.

The Federal Trade Commission’s Appliance Labeling Rule requires packages for most bulbs to include information that helps you choose the most energy-efficient bulbs for your needs. The rule applies to household bulbs, except small bulbs like night lights or chandelier bulbs.

Packaging for light bulbs, including halogen, reflector bulbs, and compact fluorescent bulbs, must provide:

. Light output -how much the bulb produces, measured in lumens.

? Energy used – the total power that a bulb uses, measured in watts.

? Design voltage – Light output and efficiency decrease when you use a bulb with a 125 or 130 design voltage in a region like ours that provides electrical service at 120 volts.

? Average life in hours – how long you can expect the bulb to last.

As you make lighting decisions, consider energy efficiency as well as light output, cost, and convenience. Think in lumens instead of watts.

Lumens measure light output. A 60-watt incandescent bulb yields 855 lumens while a 15-watt compact florescent bulb yields about 900 lumens. More light, a longer lasting bulb, and lower energy costs.

Suppose your living room table lamp is turned on for 1,000 hours a year and the power company charges eight cents per kilowatt-hour. You buy a 15-watt compact fluorescent bulb for $20, expecting it to last for about 10 years (10,000 hours). Your cost is $3.20 a year.

Your neighbor buys a regular 60-watt incandescent bulb for $1, expecting it to last about one year (1,000 hours). He will need 10 bulbs, costing a total of $10, to match the expected life of the compact fluorescent bulb and he will pay $5 a year to operate his lamp. Pity the fool!

Happy shopping. We hope we’ve brightened your day.

Consumer Forum is a collaborative effort of the Bangor Daily News and Northeast COMBAT. Send questions to Consumer Forum, Bangor Daily News, P.O. Box 1329, Bangor 04402-1329. COMBAT is a nonprofit organization with annual dues of $10. For membership information write to the above address.