Choosing the Right Bulb

The emergence of higher-efficiency lighting technologies has led to greater choice and significant energy savings. At the same time, what used to be a simple routine purchase has become much more complex. That doesn’t mean it has to be difficult, and looking on the bright side, most of these new light bulbs will last much longer than traditional incandescents, so you won’t find them on your shopping list nearly as often. In this section, we’ll address each of the major considerations involved in selecting the right bulb for each of your main light fixtures.

When shopping for new bulbs, be sure to look to the Lighting Facts label required on most common screw-based lamps. The ENERGY STAR label will help identify high-quality energy-efficient CFLs and LED lamps. To qualify, lamps must comply with specifications on energy use, light output, lamp life, and other operating characteristics. Look for ENERGY STAR to ensure you are getting lamps that have been tested and certified to meet a wide range of performance requirements. A full list of ENERGY STAR lamps is available at energystar.gov.

Light Output

The familiar wattages we’ve all used to select light bulbs since we were kids are becoming obsolete with the phase-out of traditional incandescent bulbs and wider adoption of lamps that use very different amounts of power to provide similar levels of light. While most manufacturers label their halogen incandescent, CFL, and LED lamps with the equivalent incandescent wattage— 40W, 60W, 75W, and 100W, it is useful to know how the different wattages translate in terms of light output (or lumens). Moving forward, lumens will replace wattage as the key characteristic for identifying the right light bulbs. This makes a lot of sense; after all, when you purchase a light bulb you’re looking to get a specific amount of light, not a prescribed power consumption. The table below will help you match incandescent lamps with alternative technologies to get the same light level.

Equivalent Lamp Wattages

Traditional Incandescent Typical Light Output Halogen Incandescent Compact Fluorescent LED
WATTS LUMENS WATTS WATTS WATTS
40 450 29 9-13 6-8
60 800 43 13–15 9-11
75 1,100 53 18–25 13-15
100 1,600 72 23–30 18-20
150 2,600   30–52  

Efficacy

Light bulb efficiency, referred to as efficacy, is stated in terms of light output in lumens per watt of energy consumed. While traditional incandescent lamps provide about 15 lumens per watt (lpw), halogen incandescents achieve about 20 lpw. CFLs represent a leap in efficacy, offering 55 to 65 lpw. As of 2015, LEDs are able to maintain 78-130 lpw depending on the product and application, and further efficacy improvements are expected.

Color Temperature

The shade of white light emitted by a lamp is called correlated color temperature — look for the value reported in Kelvin (K) on the lamp packaging. Lower Kelvin values (in the range of 2700K to 3000K) correspond to a warmer light comparable to a conventional incandescent that enhances yellow and red tones. Lamps with higher values (typically 3500K, 4100K, 5000K, and 6500K) give off a cooler white light that enhances blues and greens. These bulbs are often referred to as natural, bright white, or daylight lamps. The following table explains some terms you may encounter on lamp packaging. Try a few out with your family and see which you prefer. For instance, you may like a “soft white” for your living room and “cool white” for your bathroom.If the store where you are searching does not have a wide enough selection, suggest that they provide more offerings and try somewhere else.

Other Considerations

Ambient vs. Task Lighting. Some lighting technologies are better suited to directing light in a specific direction, whereas others emit light more evenly in all directions. Incandescent and fluorescent lamps are diffuse light sources, making them ideal for general lighting, such as ambient lighting for a living or dining room. On the other hand, LEDs are a very good directional light source, offering superior illumination for many task lighting applications including reading lamps, recessed downlights, and under-cabinet lighting.

Lamp Lifetime. Expected lifetime can be an important consideration when selecting bulbs for hard-to-reach fixtures as well as those that are used infrequently. CFLs and LEDs have long expected lifetimes: 8,000 to 10,000 hours for CFLs and 15,000 to 25,000 hours for LEDs. These long-lived lamps will really pay off in the most used fixtures as well as those in high ceilings or other inconvenient locations. Halogen incandescents typically operate for 1,000 hours; extended-life versions can last for 3,000 hours. Since these bulbs are inexpensive and are not negatively affected by short operating cycles, they can be good choices for closets or other spaces where lights are rarely on for more than a few minutes.

Dimming. Virtually all incandescent bulbs and the majority of LED lamps are dimmable. With LEDs, be sure to get a dimmer switch that is compatible with the lamp you’ve selected. Never use CFLs with dimmers unless the bulb is specifically labeled as dimmable.

Durability. LEDs are a great option for flashlights, headlamps, and outdoor walkway lamps. They not only use very little power and last longer, they are also shatterproof and shock resistant, and their performance is not degraded by low temperatures or moisture.

Decorative Lighting. During the holidays, most utilities experience a significant surge of electricity usage from the lighting of Christmas trees, yards, and other ornamentation. That means more pollution in the air and more of your money to the utility. LED string lights are now widely available in white and a range of colors including multi-color sets, providing a more durable and low-energy alternative. They may cost more up front, but one utility in California estimates that using LED lamps will cost you just $0.45 over the course of a holiday season, compared to $5.00 for mini incandescent string lights and $75 for large string lights!

Environmental Benefits. A single 13-watt CFL, used in place of a 60-watt incandescent light bulb, will save about 400 kWh over its lifetime. That single replacement will eliminate emissions of 700 pounds of carbon dioxide, 4 pounds of sulfur dioxide, and 6 mg of mercury on average. If your electricity is generated in a coal¬fired power plant — as is half of all electricity produced in the U.S., the emissions reductions will be roughly double.

Dollar Savings Achieved by Switching to Energy-Efficient Lamps

Replace 43-watt halogen incandescent with: Savings after 1st year Savings after 2nd year Savings after 3rd year Savings after 5th year Savings after 10th year
13­watt CFL:          
Light on 2 hrs/day $1.11 $5.21 $9.32 $16.03 $35.06
Light on 4 hrs/day $5.21 $11.92 $20.14 $35.06 $68.62
Light on 8 hrs/day $11.92 $29.85 $41.77 $68.62 $140.24
Light on 12 hrs/day $20.14 $41.77 $61.91 $100.68 $207.37
9-watt LED:          
Light on 2 hrs/day $(45.55) $(41.09) $(36.64) $(29.23) $(8.46)
Light on 4 hrs/day $(41.09) $(33.69) $(24.78) $(8.46) $31.57
Light on 8 hrs/day $(33.69) $(17.37) $(1.06) $31.57 $113.14
Light on 12 hrs/day $(24.78) $(1.06) $24.16 $70.11 $240.21

Assumptions

  Halogen Incandescent CFL LED
Lamp output (lumens) 750 825 800
Lamp life (hours) 1000 10000 25000
Lamp cost ($) $1.50 $3.00 $50.00
Electricity cost 11.9 ¢/kWh 11.9 ¢/kWh 11.9 ¢/kWh

Economics. Because high-efficiency light bulbs save electricity and last longer, they are a profitable investment. To figure out your return, you have to look at both the purchase and operating costs to arrive at total life-cycle costs. It may surprise you to learn that incandescent bulbs cost a lot more to operate than they cost to buy. When you spend 50¢ for a 75-watt incandescent light bulb, for example, you’re committing yourself to spending close to $7.00 for electricity (at 11.9.¢/kWh) over that bulb’s expected 750-hour life. In regions with high electricity prices, you could spend up to twice as much.

With a high-quality CFL, you might spend anywhere from $2 to $5 to buy the lamp, but you’ll save money in the long run. Most compact fluorescent lamps last 6,000–10,000 hours. High-qualify LED lamps are now available for $8 to $12, but not only will you save on energy, you’ll buy a lot fewer lamps over the LED’s 25,000 hour expected life. The longer a particular light fixture is used each day, the faster a high-efficiency replacement will pay for itself. See for yourself in the table below. In the CFL example, we assume a $3 price per CFL, but you may find much lower prices per unit. Even with just one switch, you come out ahead in the first year. Just imagine how much money you would save if you switched all your bulbs to CFLs and LEDs!

Did You Know? Energy-efficient light fixtures are available in a wide range of styles for use with CFLs, linear fluorescents, and LEDs. Fixtures designed specifically for use with energy-efficient bulbs will distribute light most evenly.