EmailLight bulb basics
Even a compact fluorescent light bulb that burns out prematurely uses less electricity while you use it -- but you may or may not break even. The environmental advantage of a compact fluorescent bulb also depends on its lifetime, because incandescent light bulbs take fewer resources and electricity to manufacture. We found loads of statistics estimating the environmental savings of switching to compact fluorescent light bulbs, but again -- it depends on your situation and your care in selecting and using the bulbs.
There's been a lot of buzz lately that compact fluorescent light bulbs don't last nearly as long as they're supposed to. Indeed, the majority of complaints we read were from people who expected them to last longer. Light bulb hour ratings are an average. So if a bulb's rating is 10,000 hours, that means that in lab tests, half of the bulbs lasted longer than 10,000 hours, while half didn't last that long. Still, with incandescent bulbs rated for about 1,000 hours, even CFL bulbs that last only half as long as they're supposed to result in a savings, particularly now that CFL bulbs have come down so much in price.
You'll probably save some money by switching to good compact fluorescent light bulbs, as long as you use them in the right fixtures, keep them on for at least 15 minutes at a time and exchange any defective bulbs without paying return shipping. So it's reasonable to switch from incandescent light bulbs now, before their mandated phase-out in 2012. For use with dimmer switches, new energy-saving halogen light fixtures are a better bet.
Experts agree that LED light bulbs will be superior to compact fluorescent light bulbs in many ways -- eventually. For now, they're worth considering for certain purposes, but they are too expensive and dim for most settings.
Each light bulb type has advantages and disadvantages, so most households will find a mix of light bulbs best. This report covers only light bulbs that screw into an Edison medium base. That's the most typical socket most incandescent bulbs now fit.
Medium-base light bulb types
- Compact fluorescent light bulbs -- Technically called compact fluorescent lamps or CFLs, these save energy and are long-lasting when kept on at least 15 minutes at a time. Only a few models are usable with dimmers, three-way lamps or recessed lighting, or in damp settings. Some are designed just for base-down or base-up fixtures. Drawbacks include the fact that these bulbs contain mercury, cadmium and other toxic materials. In addition, CFLs can take about half a minute to warm up to full brightness. User reports indicate that there might be a relatively high percentage of defective bulbs, or that CFLs might not typically last as long as expected. Another issue is that CFLs gradually lose 20 to 30 percent of their brightness over time, and that they can interfere with sensitive electronic devices. Also, CFLs require careful disposal (and cleanup if broken) to avoid contaminating soil and water with mercury. Most are rated to last an average of 10,000 hours.
- LED light bulbs -- These solid-state light bulbs are even cooler and more energy-efficient than CFLs, and they contain no mercury or lead. Experts say these are particularly good for light fixtures that require instant illumination (such as stairways or garage doors), where bulbs are difficult to change or where a focused task light makes the most of directional light. The biggest drawback right now is cost. In addition, LED light bulbs are relatively dim. They get even dimmer during their lifetime, and they don't show colors well. There's not enough feedback as of yet to draw any firm conclusion about reliability or longevity.
- Halogen light bulbs -- These light bulbs also turn on instantly. Unlike CFLs, they can be used with standard dimmer switches, contain no mercury and are unaffected by frequent on-off cycling. New energy-saving halogen light bulbs use about 30 percent less electricity than incandescent bulbs and last an average of 3,000 hours. Halogen bulbs are good for both general and focused lighting. However, these save less energy than compact fluorescent and LED light bulbs. The light they give off is slightly cooler than most incandescent or soft white light bulbs.
- Incandescent light bulbs -- These are the ordinary light bulbs that are the least efficient, producing more heat than light. They cost the least initially, but cost the most in the long run (taking electricity into account). For environmental reasons, legislation is phasing out most incandescent light bulbs by 2012 (and in some countries much earlier). Most incandescent bulbs last 1,000 hours.
Except for halogen light bulbs, whose light is usually white, each type of light bulb is available in various color temperatures, usually specified in degrees Kelvin (K). Most light bulbs range from a warm 2,700K through various steps of cooler, bluer, to a very bluish-white 5,000K, often called full spectrum.
Lifetime in hours means the median number of hours that samples of the light bulb model have been tested to last. That means that half the light bulbs will last longer, but half will last a shorter time. So it doesn't mean you can expect every light bulb of that model to last at least that long; half of them won't. Light bulb lifetime ratings are calculated under ideal conditions of temperature, humidity and on-off cycling -- which is unlikely to match your situation. (For example, if a compact fluorescent light bulb is turned on for only five minutes at a time, its estimated lifetime is reduced to that of an incandescent light bulb.)
Lumens is a measure of light output, but both the effective and perceived light output can vary in several ways. Lumens are measured for fluorescent light as the average light output at 40 percent of the rated lamp life, because most of their decline in brightness occurs earlier. Also, light bulbs that put out the same lumens may seem dimmer or brighter depending on the fixture. A light bulb used in a focused task lamp, for example, may not need as many lumens as a light bulb used in a floor lamp that radiates light all around. The color temperature of the light bulb can also affect how bright its output appears to be, with the effect varying somewhat depending on the type of light bulb. Also, the human eye perceives less difference in brightness than the objective increase in lumens measured by lab instruments, so it takes a bigger increase to be noticeable to the human eye.
Warranty is usually specified in hours or years, but retailers and manufacturers vary a great deal in how they handle warranty claims. As many owner-written reviews testify, a light bulb warranty doesn't help much if the company requires you to pay shipping to return defective bulbs. Retailers may or may not accept returns. Also, many light bulbs are designed for specific kinds of light fixtures, and using them with a dimmer switch, an enclosed or recessed fixture, or in a damp setting -- even with the same medium-base screw-in socket -- may void the warranty.
Starting time isn't the same as run-up time. Compact fluorescent light bulbs must start within one second to earn Energy Star certification, but may still take up to 30 seconds or so to attain full brightness. LED, halogen and incandescent light bulbs start so fast that the delay is imperceptible. When first getting used to compact fluorescent light bulbs, the delays can be disconcerting. Reviews warn that in a few situations the delays can be dangerous -- for example, if you depend on instant light for safety on stairs.
Most dimmer switches are designed for use with incandescent light bulbs. Reviews warn that even when labeled "usable with dimmers," it's possible that a compact fluorescent light bulb won't work with your dimmer switch. The same is true of three-way light fixtures: A three-way compact fluorescent light bulb may or may not work. Your best bet is to replace incandescent light bulbs first in ordinary light fixtures with plenty of airflow that stay on for hours at a time. Both heat and cycling on and off often can drastically shorten the lifetime of compact fluorescent light bulbs.
Light bulbs and other health concerns
Full-spectrum lighting isn't the only health concern that various experts have raised about light bulbs. Other concerns include electromagnetic fields (EMFs) and the possible release of toxic chemicals, including mercury, if a compact fluorescent light bulb is broken. We found some studies of both risks. UV light is of less concern, because reviews say that light bulbs emit relatively little UV light compared with sunshine.
Although there's evidence that exposure to electromagnetic fields is hazardous for children -- with a connection to leukemia rates -- it's not clear whether or not EMFs pose a problem for adults. Apparently some people are more sensitive to such fields than others; if you've ever gotten a headache from one or more light fixtures or bulbs, you're apt to be one of them. Incandescent light bulbs don't emit a high electromagnetic field, but some compact fluorescent light bulbs do -- certainly the ones that use an iron-core electromagnetic ballast. If EMFs are a concern, select a bulb with a solid-state electronic ballast.
In addition to mercury, fluorescent light bulbs contain other toxic materials. Most contain cadmium, lead, hexavalent chromium and polybrominated biphenyls. Hence, reviews say it's a good idea to familiarize yourself with the safest cleanup procedure when buying compact fluorescents (or any fluorescent light bulb, for that matter).
Of course, disposing of unbroken defective or used fluorescent light bulbs is a major environmental concern. A few localities have ample recycling facilities in place, but proper disposal of hazardous light bulbs is still a real problem in many areas.