Compact fluorescent light bulbs (CFLs) have received a lot of support from environmentalists over the past few years, and for good reason. The now-iconic "swirly" bulbs are roughly 75% more efficient than standard incandescent bulbs, and they last up to 10 times longer, saving users money, hassle and reducing our environmental impact. At the same time, much has been said about the drawbacks of CFLs. What is less discussed is where CFLs don't make as much sense, and where you would do well to consider alternatives.
First, it's true CFLs do contain a small amount of mercury, which is toxic, though that amount has been steadily dropping, and there are reasons why you shouldn't over-worry about this issue, including a lack of evidence of harm and safe handling strategies. Still, my coauthors of the new book Green Lighting and I recognize that some people are concerned. In addition, there are cases when CFLs might be avoided in favor of LEDs or halogens.
LEDs (light emitting diodes) last for thousands of hours and are even more efficient than fluorescents, and they tend to produce crowd-pleasing, adaptable light, as our recent tests showed. LED bulbs are becoming widely available, with prices that have plummeted (Home Depot's EcoSmart line starts at $20 each). Halogens are less efficient than CFLs and LEDs, but they are 10 to 40% more efficient than standard incandescents and they last two to three times longer. They also work well with dimmers.
So here are some areas where we would recommend considering LEDs or halogens over CFLs:
CFLs don't like to be cold, so they operate slower and may suffer from shorter lifespans if they are placed in outdoor or unheated fixtures in cold climates. True, there are models built with cold-weather ballasts, so that may be one option, although most of those are not designed for very cold temperatures, so you'll have to check the manufacturer's rating. So-called cold cathode CFLs are also generally better at lower temperatures, and they switch on instantly, though they aren't made in models that are super bright.
Alternatives: LEDs, on the other hand, are more tolerant of cold temperatures (though they can see decreased lifespan in very hot temperatures). The longer lifespan of LEDs also means you'll have to change them less, which is handy because who wants to change bulbs outside when it is freezing out? Halogens are also less affected by cold, though they don't last as long as CFLs or LEDs, and they waste a lot of energy as excess heat -- who wants to pay to "heat up" the outdoors?
Rapidly switching CFLs on and off decreases their lifespan, by as much as 85%, according to experts we interviewed for Green Lighting. Some scientists have estimated that a CFL can only tolerate around 7,000 on-off cycles. This means that putting a CFL in a closet or in a back room you rarely use is probably going to mean that it won't last as long as advertised. Since CFLs have come down so much in price, that isn't necessarily the worst thing in the world, since you'll still save energy over incandescents, though you won't see much savings because the light isn't used much.
Alternatives: If you want to maximize your investment in lighting technology, get halogens for fixtures that are switched frequently, as they can handle the cycles, but are still more efficient than incandescents. If you can afford the investment, LEDs would be a good option, since they will last extremely long, meaning you don't have to worry about burn outs.
The glowing part of CFLs (sometimes called the burner) is made of glass, which means it is relatively fragile. If that breaks, a small amount of mercury can be released, so it's a good idea to try to avoid it. This means CFLs aren't good choices for applications that are going to get banged up. The bulbs also tend not to like vibration, which can shorten their lifespans. A few models are being produced that are designed for mild vibrations, such as for ceiling fans, but they often aren't easy to find.
Alternatives: Perhaps ironically, LEDs have been the choice for industrial lighting applications for years, especially for the fossil fuel and nuclear industries, even though they use less energy than competing technologies. LEDs are solid state devices that are extremely tough, so they work great on oil platforms, in mines and in factories, as well as for street signage. Halogens can be ok for mild vibrations, but shaking the filament may decrease it's life over time, and they still contain glass that can shatter.
CFLs are relatively large, so they typically are not used on boats, cars and other vehicles. They are also prone to breakage and do not do well with cold or vibrations.
Alternatives: LEDs are rugged, small and last a long time, so they are seeing heavy deployment in marine and auto applications. Halogens were recently dominant in consumer cars, but LEDs are rapidly taking over in the high-end market.
Most CFLs are not dimmable, although some models are produced with the feature. Most of those don't work with traditional wall dimming switches, although newer controls are able to handle them. Some CFLs have a dimmer switch built into the bulb's ballast, but that's not always convenient. Even with the best dimming ballasts, CFLs don't dim as smoothly or as completely as the incandescents people are used to. They've come a long way, but the user experience isn't quite perfect.
Alternatives: If smooth, full dimming is important to you, you're better off with halogens at the moment. Remember too, dimming saves money, because lower lights use less energy. Many new LED bulbs are dimmable, often even with many dimmer switches, but most aren't quite as smooth as incandescents just yet, and there are some compatibility issues. If you don't need perfect dimming and are willing to invest some money up front, LEDs can serve you well, especially if you have a light-intensive commercial outfit.
At a fact-finding trip to the lighting district in NYC, we overheard a salesperson telling customers that "You don't want CFLs in your home." In truth, CFLs have improved their light quality dramatically over the past few years, and the newest soft white, Energy Star-qualified models come quite close to replicating incandescents. This is not the case with many discount brands, however, which are often described as "harsh." In general, CFLs are recommended more for task lighting and less for ambient settings.
Alternatives: The newest LEDs produce bright, clear, relatively flattering light that is also approaching incandescents. In a recent test, TDG's staff preferred LED light to any other technology. Some LEDs also offer the ability to adjust the light quality or color. If you can't afford them yet, take a look at halogens, which have softer, warmer light than fluorescents.
Although we pointed out that much of the fear about mercury in CFLs is overblown and misplaced, it's true the bulbs contain a small amount. You could consider investing in "safety" CFLs, which have a silicone shell around the glass, reportedly to contain any mercury in the event of a breakage. Or consider alternatives for children's rooms, since it's true the young are most susceptible to damage from the toxic element.
Alternatives: LEDs and halogens contain no mercury, so they can be a safer choice, especially in children's fixtures that may be knocked over. Incandescents result in more mercury being released into the environment, since they are so much less efficient, and most mercury pollution comes from coal-fired power plants. So that's something to think about.
CFLs have improved over the past few years, and they are available in more shapes and sizes than ever. They are an affordable green technology that will save you money, but they have some limitations. Luckily, there are other alternatives as well.
Also come out and meet the authors of Green Lighting in Ossining, New York on December 14!
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