Incandescent vs Compact Fluorescent Light Bulbs (CFL) – Energy Savings Worth the Cost?

cfl light bulbYou might know them as “those spiral light blubs,” or “the eco-friendly light bulbs.” They’re compact fluorescent light bulbs, or CFLs, and while they’ve had a reputation for lasting longer and using less energy for a couple of decades now, the government has recently started regulating their efficiency. With these new regulations and increasing efforts to save energy at home, lower utility bills, and find greener energy solutions, demand for CFLs is rapidly increasing.

Believe it or not, the move away from traditional, incandescent light bulbs has actually created a backlash among some who wish to keep the look and feel of Thomas Edison’s original design. Incandescent bulbs are still available of course, and there are still times when they may be more valuable than a CFL. So how do you know when it’s time to switch to a CFL?

What Is a CFL?

cfl light bulb whiteFirst, you need to understand the technology behind both kinds of bulbs. Incandescent bulbs work by heating up a small wire called a filament. Electric current heats the filament so much that it glows. The incandescent bulb really is more of a heating element that happens to put out some light. If you had an Easy-Bake oven, used a light bulb to incubate chicken eggs in science class, or noticed that you break a sweat when you sit next to your desk lamp long enough, you’ve experienced the heating effects of incandescent bulbs.

In fact, 90% of the electricity used by a standard light bulb is converted to heat. While this conversion is wasteful enough by itself, it’s compounded by the fact that you probably end up using more energy from your air conditioner just to cool your home from the heat that comes from your lights. Since the filament only produces light at high temperatures, it is prone to burning out rather quickly, which is why you’re always changing bulbs all over the house.

In contrast, a compact fluorescent light (CFL) is just like the standard florescent lights that are common in commercial buildings. Instead of a long, fat tube, the CFL has a smaller tube that’s manufactured in a swirl shape so it fits the basic form of an incandescent bulb. Florescent lights, compact or conventional, work by exciting gases with electricity. Because little heat is generated, most of the electricity used goes directly into providing light. It’s less wasteful, so you end up spending less on your regular electric bill by making your home more energy efficient, and the bulbs last much longer.

Advantages of CFLs

  1. High Efficiency. CFLs use 20% to 33% less electricity than incandescent bulbs.
  2. Long Life. With no filament to burn out, florescent lights tend to last 8 to 15 times longer than incandescent bulbs. Their up-front price is higher, but by using less electricity and helping you avoid changing bulbs, you’ll end up spending less over the life of the bulb with a CFL.
  3. Safety. CFLs are even safer than incandescent bulbs, since lower temperature means a decreased risk of home fire.

Disadvantages of CFLs

  1. Longer Warm-up Time. Modern CFLs still take a few minutes to warm up before they reach their full brightness. It can take a few days or weeks to get used to the delay before the light really “turns on” and shines at 100% capacity.
  2. Higher Initial Expense. Though most prices have dropped dramatically, CFLs still cost more than standard incandescent bulbs. Individually, CFLs sometimes sell for as much as $4, and when you buy them in packs of four or more, the price is often as low as $2 each. In some parts of the country, utility companies are subsidizing CFL purchases, and some even give them away for free!
  3. No Dimmer Compatibility. Most CFLs don’t work with dimmer switches. Dimmable CFLs do exist, but they can cost $15 to $20, far more than regular CFLs.
  4. Mercury. CFLs contain a small amount of mercury, which is toxic. It’s not a day-to-day worry, but when the bulbs eventually burn out, you can’t just toss them in the trash. Thankfully, most hardware stores will accept them.

cfl incandescent bulb cartoon

Best Uses for CFLs

The more you use a particular light fixture, the more you’ll save by choosing a CFL as your bulb. CFLs are best-suited for lights that you leave on for longer periods of time. Years ago, I managed a high-rise residential building that used incandescent bulbs to light the hallways 24 hours a day. Back then, CFLs cost $10 each, but we still saved hundreds every month by installing a few dozen. Today, since prices have fallen significantly, they’re a more accessible choice for your residential lighting needs.

If you leave a single 100-watt bulb on 10 hours a day, you’ll spend about $3 a month on your electric bill for that light (assuming you’re paying 10 cents per kilowatt hour). At that rate, converting to a CFL would save at least $2 in electricity costs alone, every month, for that single light bulb. If you buy a four-pack, you’ll make your money back in just a month. For a bulb that you use for only one hour a day, it would still only take about a year to break even.

When Incandescent Bulbs Are Still Best

Despite what you may hear, CFLs aren’t necessarily suited to every situation. There are still plenty of times you might wisely prefer to use an incandescent bulb.

  1. Rarely Used Lights. If you seldom use a particular lamp or other lighting fixture, you won’t see many benefits to converting. It will take an annoyingly long time to warm up while saving very little energy. A closet light that you use for only a minute or two, for example, is not a good candidate for a CFL.
  2. Cold Outdoor Lighting. CFLs operate poorly as outdoor lighting when the weather is cold. Because of this, I use incandescent flood lights on a motion sensor above my garage. CFLs are very dim in the winter cold, particularly for the five or so minutes it takes for them to warm up. In the summer, I switch back to the CFLs, which quickly provide adequate lighting at warmer temperatures. If I needed to leave outdoor lighting on all night, then the CFL warm-up time would not matter as much.
  3. Dimmable Lighting. Incandescent bulbs are ideal for lights that are on a dimmer, since dimmable CFLs still cost a lot more.
  4. Non-Standard Bulbs. CFLs can be expensive in unusual sizes. For example, the small reading light beside my bed uses an atypical small bulb. A CFL is available, but its cost is not justified considering how much I use it.

Final Word

Especially now that prices have dropped significantly, converting to compact fluorescent light bulbs can be great for the environment and your wallet. But incandescent bulbs aren’t obsolete, at least not yet. And despite some rumors, they’re certainly not being outlawed. However, manufacturers will need to meet better efficiency standards and will encourage the sale and use of CFLs. By understanding both types of light bulb technologies and their best applications, you can save a tremendous amount of money while still enjoying the quality of light that you’ve come to expect.

Have you converted to CFLs? Where do you use them, and how much have you seen your monthly electric bill drop? Where in your home do incandescent bulbs still make the most sense?

  • Sustainable PF

    We’ve converted most lights but we’re finding LED is getting cheap enough to use in some circumstances (such as outside). I wrote about this topic and really crunched the numbers early on in our blogs existence. Looking at the financial data I think it makes sense to switch:

  • Brad Buscher

    CFLs are a better solution, both economically and environmentally. CFLs and fluorescent lamps give off the same amount of light as their traditional incandescent counterparts, but they require considerably less electricity, which in turn reduces the damaging effects electric power generation causes to the environment. Incandescent light bulbs actually require four times the amount of energy to produce equivalent light in a fluorescent lamp. Fluorescent lamps are four to six times more efficient than incandescent lamps, reducing the power demand from local utilities. While incandescents do not contain mercury, they still contribute to its release into the environment. Because burning coal to generate electricity releases mercury into the air and incandescent bulbs use more electricity over their lifetimes, they are responsible for more energy consumption and ultimately more mercury emissions than CFLs. With a proven packaging configuration and proper disposal, CFLs can be used effectively without releasing harmful mercury vapor.

    If a bulb is broken or burns out, it should be properly cleaned up and recycled—it cannot be disposed of in landfills. To reduce the risk for mercury vapor exposure, CFLs and fluorescent lamps should be safely handled, stored and transported to recycling facilities in a package that is proven to effectively contain hazardous mercury vapor. Find out more about how to minimize environmental risks and safely package CFLs here:

    If a bulb breaks, consumers can learn more about clean-up procedures here:

  • Lighting specialist

    Lamp life in fluorescent bulbs is based on never being turned off. Every time you turn them on and off you shorten the lamp life. In the 60’s and 70’s the sales pitch was fluorescent lamps were very inefficient and should be eliminated. Consider the millions of dimmers being used in this country for incandescent that will end upbeing scrapped at roughly 22.00 dollars each plus removal. CFL and LED dimmers must be compatible with the specific lamp manufacture or they won’t work or at best provide ten to twenty percent wattage variation. We just lost some more freedom and alot of money and most of you didn’t even know it. Where is GE’s NELA Park opinion on this?