For the greatest savings, switch to compact fluorescents

CFLs remain the go-to choice for energy efficiency. They last longer and consume less electricity than a standard incandescent. A 13-watt CFL, for example, gives off the same amount of light as a 60-watt incandescent and burns for 10,000 hours, compared with 1,000 hours for the conventional bulb. A typical CFL saves about $30 in operating costs over its lifetime.

Early CFLs didn’t always deliver on light quality or convenience, but aesthetic performance has improved vastly in recent years. They now come in warm, neutral, and cool “colors,” and major manufacturers like GE have started enclosing the telltale spiral in a conventional bulb shape so it’s less obtrusive.

You get the biggest bang for your buck with CFLs in places where you would otherwise use incandescent bulbs: floor and table lamps and standard overhead fixtures. They last longer when they’re not flipped on and off constantly, so they’re especially good in rooms that see a lot of activity throughout the day, such as a kitchen or a playroom.

A couple of caveats: CFLs can be glary, so they’re not the best choice in downward-pointing fixtures like chandeliers, and most don’t work with dimmers or timers. Because the bulbs contain mercury, they can’t be thrown out in the regular trash. If you bought them at a home center, you should be able to return them there for recycling, or log on to recycleabulb.com to find a disposal center near you.

Cost and savings: Expect to pay $2 to $15 for a CFL, versus 50 cents to $1 for a comparable incandescent, but the CFL will last at least 10 times longer and cost up to 75% less to operate.

Make your existing incandescents less expensive to run

By simply lowering the wattage of an incandescent bulb by 15 watts — from 75 to 60, for example — you can knock 15% off the operating cost. And you may not even notice the difference in brightness. “A small reduction in wattage isn’t discernible to the eye,” says Brett Sawyer, a consultant who blogs about sustainable home design.

If the light is on a dimmer, for every 10% you lower the brightness, you’ll double the bulb’s life. Try this next weekend, Sawyer says: Replace your most-used bulbs with ones at least 10 watts lower. If you don’t notice the difference, then replace all the incandescents you can with lower-wattage bulbs. Combine that with CFLs in selected fixtures, and you’ll achieve a “light layering” effect that saves money without compromising light quality, and without a hefty upfront investment.

Cost and savings: For every 15-watt reduction, you reduce energy use by 15%. And a $10 dimmer, once installed, costs nothing to use.

Keep an eye on new bulb technologies

Spurred on by new energy requirements set to go into effect in 2012, bulb manufacturers are working feverishly to come up with more efficient versions of the standard incandescent. Presently, companies including GE, Sylvania, and Philips offer high-efficiency incandescent and halogen bulbs that use less energy than standard incandescents while delivering the same light quality.

And research is proceeding apace on how to bring the dramatic energy efficiency of LED technology to residential products. These lights, which require very little current and last even longer than CFLs, are prohibitively expensive for home use (except in certain applications like under-cabinet strip lighting), but that’s likely to change in the coming years.  

Think beyond the bulb to save on lighting costs

Changing bulbs is one way to reduce your lighting bill, but it’s not the only way.

Motion sensors: Great in rooms where the occupants can’t be counted on to turn off the light, such as a kids’ playroom. Devices cost $15 to $50 and take about an hour to install.

Door-jamb switches: Best in a pantry or closet; opening the door activates the light. As much a convenience as it is an energy saver—as long as you remember to close the door. Devices starts at about $15.

Windows: You’d be surprised at how  much a simple window cleaning can instantly improve natural light.

Energy Star fixtures: Designed for CFL and LED lights, these can save up to $70 a year in energy costs. Go to energystar.gov to find links to manufacturers.