Compact fluorescent light bulbs (CFL's)

If you know only a little about CFL's, you've probably heard that they save a little energy but they contain a lot of toxic mercury.  But the truth is, they save a whopping amount of energy, and the mercury scare is greatly exaggerated.  On this page I'll give you the lowdown on CFL's in great detail.

I first recommended CFL's on this site way back in the 1990's, when they were rare.  It was kind of neat back then to let people in on a big secret.  It's not such a secret any more, but I'm glad people are saving energy with CFL's.

To understand why CFL's are a big deal, we first need to see why regular lightbulbs are so lame.  Environmental Defense has the best explanation of what's wrong with regular light bulbs:

"Though we call them light bulbs, traditional incandescent bulbs are actually small heaters that give off a little bit of light--something you know if you've ever touched a bulb that's been on for a while.  These bulbs were technological wonders when they were patented in 1880, but today they are inefficient dinosaurs.  They waste energy and money, and they are responsible for millions of tons of global warming pollution."

Compact fluorescent light bulbs (CFL's) are one solution -- they use about 75% less electricity and give off only a little bit of heat.

Here's are the benefits of CFL's:

• Use 75% less energy than regular light bulbs.
• Last about 10 times as long as regular light bulbs.
• Produce similar quality light as regular light bulbs (nothing like old-style fluorescents).
• Cost as little as $1.50.
• Don't generate ridiculous amounts of heat (which you would have to pay to remove with AC).

And here are the downsides:

• Most of them can't be used with dimmer switches. (Some can; check the package.)
• Cheap ones burn out really quickly. Buy Energy Star-rated bulbs, or bulbs with a warranty.
• They start dim and take a minute or two to reach full brightness.
• They contain a tiny amount of mercury, which might be an issue if you break a bulb and you're careless about how you clean it up.  (More on this in a minute.)
• If you use an illuminated wall switch to control them, they might burn out faster.
  
• They produce a higher electromagnetic field than regular bulbs, and there is controversy about whether this has health effects.  (More on this in a minute, too.)
  

Old-style bulbs are such big energy-wasters that many governments are banning them.  That includes the U.S. and Australia.  They're doing this to save energy, because saving energy reduces pollution.  (Power plants put out tons of carbon, sulfur dioxide, mercury, and more.)

Let's start out by looking at the savings you get with CFL's. Right off the bat, you save 70% on energy as soon as you screw them in. Here's a calculator to demonstrate:

And that's just the electricity savings.  Since a good CFL lasts 10 times longer than an old-style bulb, that's a lot fewer bulbs to buy.  This is especially important for large commercial applications, where the cost of labor to constantly replace old-style bulbs can be significant.

You'll save even more in summer months, because CFL's run cooler than old-style bulbs, so you'll spend less money to cool your home or office.  This is balanced by the fact that you'll see little savings during the winter, because your savings on lighting will be negated by higher heating bills.  (Your old incandescent lights were helping to heat your home.)  It's unlikely you'll pay more overall in the winter by using CFL's, it's just that you likely won't see much overall savings during winter, either.  So in summary:

To figure your electricity savings manually, ignoring heating/cooling issues, use this formula:

For example, let's say you replace ten 60-watt bulbs with ten 15-watt CFL bulbs. That saves you 45 watts per bulb, or 450 watts for all ten. Let's say all your lights were on for six hours a day, five days a week. That's thirty hours a week, or about 1500 hours a year. So your 450 watts savings times 1500 hours a year = 675,00 watt-hours. Divide by 1000 and you have 675 kilowatt-hours (kWh).  If you're paying 15¢ per kilowatt-hour, then you'll save $101.25 a year.

If you don't like my calculator there's also a calculator at EnergyStar.gov.

Modern CFL's produce great light.  If you saw the old ones and didn't like the kind of light they put out, you're in for a surprise.  Here's what Popular Mechanics said:

The results surprised us.... [H]ere was the real shocker: When it came to the overall quality of the light, all the CFLs scored higher than our incandescent control bulb.  In other words, the new fluorescent bulbs aren't just better for both your wallet and the environment, they produce better light.

How to buy CFL's

When you buy CFL bulbs the package will be labeled to show you how many watts it's equivalent to.  For example, a 15-watt CFL bulb package will say something like "60 watt equivalent". They have to say that otherwise people would look at the package and think, "15 watts? That's not nearly enough light!" But it is, because a 15-watt CFL bulb puts out as much light as a standard 60-watt bulb.

Although CFL's generally last for years longer than regular bulbs, the cheap kind can burn out quickly.  I therefore recommend buying only Energy Star-rated CFL's, or at least ones that come with a 5+ year warranty.  If the package says "lasts five years" that's not good enough, you want a 5+ year guarantee.

Make sure to get a color temperature you'll be happy with.  The light bulbs you're replacing are probably "warm", around 2800k.  Anything above around 3500k will have a bluish tint to it, and the higher the blue, the "colder" (more blue) it gets.  If you want similar light to what you probably have now, go for "warm" CFL's, less than 3500k, the lower the better.

If you're in a super-cold environment, note that most CFL's run dim in very cold temperatures, and most won't run at all below 20°F.  (Paralite makes some they claim will work down to minus 20°F.)  If you're using them outside as floodlights, then make sure you get the kind that are labeled for cold-weather use.  One reader notes that he put a $10 bug light sleeve around the light which acted like insulation, and kept the light just warm enough that it would work.

CFL longevity

It's no secret:  the cheaper CFL's often burn out quickly.  Sometimes even a batch of name-brand bulbs can be bad.  I strongly recommend you buy only Energy Star-rated CFL's (look for the Energy Star label), or at least get bulbs that come with a warranty.  Energy Star bulbs have to meet strict specs for lifespan, and they have to maintain 80% of the initial light output at 40% of their rated lifetime. (Energy Star)

In Consumer Reports' rigorous testing, after 3000 hours with frequent on-off cycling, most of their CFL's are still going strong, and the Energy Star bulbs are lasting longer than the non-ES bulbs.  (CR article, subscription required)

It's never better to leave the lights on

It's never better to leave the lights on when you leave a room.  It's always better to turn them off.  It doesn't take more electricity to turn them back on, contrary to some stupid myth.  There is no surge when you turn on a CFL (or anything else in your house), in practical terms.  "In practical terms" means any surge that happens is so tiny it can't even easily be measured.  You're certainly not paying for it, because it's too microscopic to show up on your electric bill.

If a CFL used twice as much energy as normal for the first full second it was on, then that would mean you're paying for one extra second of electricity.  You'd have to flip the light on close to 10,000 times before you'd pay even one penny in electrical costs.

Mythbusters did a story on this and confirmed what I'm saying.  They concluded that it would pay to keep a CFL light on only if you're leaving the room for 1/66th of a second or less.

CFL's and illuminated light switches

Light switches that light up when the main light is off can cause problems with CFLs.  Illuminated light switches work by passing some of the current through the switch to light it up when the switch is off, and that tiny amount of current also passes through to the bulb.  With an old-school incandescent bulb there's no problem, because there's not enough current for the bulb to fire.  But some CFLs are sensitive to even small amounts of current, and can flicker when the switch is off.  Besides being annoying, this can also potentially burn out the CFL bulbs faster.  Solution:  Either use regular (non-illuminated) wall switches, or use LED light bulbs.  (More from Will Nicholes.  Also worth noting is that a master electrician thinks that CFL flicker on a lighted switch is abnormal and that any CFL flicker means there's actually a wiring problem.)

The great mercury scare

Let me debunk this the easy way:  The median mercury exposure from breaking a CFL is only 0.07 mcg, while single serving of Albacore tuna has 48 mcg.  The tuna has seven hundred times as much! (Illuminating Engineering Society, 2009)  The amount of mercury exposure by breaking a CFL is just not that significant.  As Popular Mechanics put it:

Each bulb contains an average of 5 milligrams of mercury, "which is just enough to cover a ballpoint pen tip," says Leslie, associate director of the Lighting Research Center at Rensselaer [Polytechnic Institute]. "Though it's nothing to laugh at, unless you wipe up mercury [without gloves] and then lick your hand, you're probably going to be okay.

And actually, Consumer Reports says CFL's have even less mercury than is commonly reported.  According to their tests, all the bulbs had a lot less than 5 mg, and some had less than 1 mg. (CR article, subscription required)

And while the risk from a broken CFL is tiny, the risk from a bulb that never breaks is zero. You'd think that would be obvious, but some of the hysteria surrounding CFL's is coming from pages that say that just having CFL's installed in your home is "killing you slowly" -- which is absolute nonsense.

If a bulb does break, you just take some simple steps to minimize your exposure when cleaning it up. You certainly don't have to call in a hazmat team. One woman got bad advice that she needed to do just that, and the anti-CFL folks have been having a field day with that one, not admitting that the advice this person received about employing a hazmat team was simply wrong.

Those who are still concerned can just use a bulb with a plastic cover. Check out the picture at right of a bulb I bought recently. It's really unlikely that one of these bulbs will break in the first place, but if it does, it's sealed. Problem solved.

Another idea being bandied about is that the use of CFL's is resulting in a lot more mercury getting into the environment, in general. Not true, because power plants put out tons of mercury. They put out more mercury to power the bulb, than is contained in the bulb. (Ohio EPA)   In fact, for each bulb you don't replace with a CFL, you're putting ten mg. of mercury straight into the air. (Popular Mechanics)  Using CFL's dramatically reduces mercury emissions at the power plant.

And mercury at the power plant is worse than mercury in lightbulbs, because power plant mercury goes straight into the air where it's impossible to recycle. By contrast, every single Home Depot and Ikea take unbroken CFL's for recycling.

Next, let's put the amount of mercury in perspective:

• 3000mg - Common thermostats (max. amount)
• 500mg - Old mercury-filled thermometer
• 500mg - Dental filling
• 25mg - Watch batteries from circa 1958-2008 (now going mercury-free)
• 13.6mg - Mercury emitted at power plant to power an old NON-CFL bulb
• <1 to 5mg - Compact fluorescent light bulb
• <1 to 3 mg - Low-mercury CFL's (e.g., Phillips and Turolight)
• 0.000007 mg - Median exposure from a broken CFL
  Figures from Energy Star Canada and GE, exposure figure from Illuminating Engineering Society.

See also the EPA's info about household items that contain mercury, here and here.

Let's also remember that tubular fluorescents have been used in commercial and office buildings for decades. This is not a new technology at all.

So now let's look at the politics behind all this:  I'd really like everyone to understand that the scare warnings about mercury in CFL's have been coming from Republicans who want to fight conservation. This isn't partisan bickering, it's a matter of public record, as we'll see presently. What's especially ridiculous about this is that the GOP has fought tooth and nail against pollution controls for decades, and now they have the gall to claim to be concerned about toxic mercury. Please. Their real goal is to keep us from saving energy.

Think I'm exaggerating? Here's the proof. Rep. Ted Poe (R-TX) took the floor of the House to blast CFL lightbulbs and opened up with this flabbergasting statement:

"Congress passed an energy bill which should have been called the 'Anti-America NON-Energy Bill' because it punishes Americans for using energy, rather than finding new sources of affordable energy."

There you have it. Any attempt to reduce our energy use isn't just unnecessary, it's supposedly anti-American! And reducing energy use (and therefore pollution) is tantamount to punishment. Punishment! Since Poe is an unabashed enemy of conservation, is it any freaking wonder that he opposes energy-saving light bulbs?!  Is it any surprise that he will bring up any possible defect he can find in CFL's in order to further his anti-conservation agenda?

It gets richer. In Poe's mind, all we need to do is magically find some new sources of affordable energy. And what do you think he has in mind? Why, drilling the Artic National Wildlife Refuge and America's beaches for oil, for starters, something the GOP has been eager to do for years.

Anyway, when Poe has made his anti-environmental agenda so clear and plain, are we really supposed to take him seriously when he starts frothing about the environmental calamity posed by mercury in CFL bulbs? Not.  Republicans vote consistently against any measure to reduce pollution in general, and mercury specifically.  If they're so concerned about mercury exposure with CFL's, why are they voting against measures to reduce mercury pollution? As soon as Rep. Poe and his cohorts vote for any other measure to reduce Americans' exposure to toxins, that's when I'll start taking them seriously.

On the 2007 House energy bill, which CFL's were a part of, 221 Democrats and only 14 Republicans voted for it. Of the "No" votes, over 96% were cast by Republicans. (USA Today)  And congresspersons who voted against clean energy took four times as much money from oil companies than those who voted in the public interest. (Oil Change International)  If you're a Republican and you're offended by my pointing out that Republicans having been fighting conservation on spurious grounds -- then please get your fellow Republicans to stop fighting conservation on spurious grounds.  Don't get mad at me for simply pointing out what's actually happening. Because if the GOP wasn't being completely ridiculous about this issue, then I wouldn't be pointing out that they're being completely ridiculous about this issue.  It's not my fault they're being unreasonable, I'm just the one pointing it out.

And for all those who are trying to pin CFL's on Obama, the bill was passed in 2007, and signed into law by President Bush.

All that said, there really should be a warning on the package about the mercury. Really, anything that's a potential mercury hazard should be labeled.  I believe the scare is way overblown, but the mercury notice and the cleanup steps should be included in the product. I don't think the small amount of mercury in the bulbs is a good reason not to use them -- it's just not that big a deal.

More on mercury in CFL's:

• Lawrence Berkeley scientists debunk the CFL mercury scare
• EPA's actual cleanup guidelines (no, you don't have to call in a hazmat team)
• Maine EPA's study about mercury released from broken CFL's

CFL's and electromagnetic fields (EMF)

There is controversy over whether the electromagnetic fields (EMF) from CFL's constitute a health risk.  On the one hand, the scientific bodies of governments around the world say that there is no risk from most EMF in general or from CFL's in particular.  On the other hand, some scientists and advocacy groups have blamed EMF on a huge variety of ailments (including cancer, diabetes, and even back pain), and some research has indeed suggested a connection between EMF and health issues.  Here's an example of the widely differing opinions on EMF in general:

World Health Organization:  "Approximately 25,000 articles have been published over the past 30 years about non-ionizing radiation. Scientific knowledge in this area is now more extensive than for most chemicals. Based on a recent in-depth review of the scientific literature, the WHO concluded that current evidence does not confirm the existence of any health consequences from exposure to low level electromagnetic fields."

Dr. Magda Havas (PDF), writing in a peer-reviewed journal:  "Although the position of most international health authorities, including the World Health Organization, is that this form of energy is benign as long as levels remain below guidelines, an increasing number of scientific studies report biological and health effects associated with electromagnetic pollution well below these guidelines (Sage and Carpenter, 2007). Epidemiological studies have documented increased risks for childhood leukemia associated with residential magnetic fields exposure (Ahlbom et al., 2000), greater risk for various cancers with occupational exposure to low-frequency electric and magnetic fields (Havas, 2000), miscarriages (Li et al., 2002), Lou Gehrig's disease (Neutra et al., 2002), brain tumors associated with cell phone use (Kundi et al., 2004), as well as cancers and symptoms of electrical hypersensitivity (EHS) for people living near cell phone and broadcast antennas (Altpeter et al., 1995; Michelozzi et al., 2002). Laboratory studies report increased proliferation of human breast cancer cells (Liburdy et al., 1993), single- and double-strand DNA breaks (Lai and Singh, 2005), increased permeability of the blood brain barrier (Royal Society of Canada, 1999), changes in calcium flux (Blackman et al., 1985), and changes in ornithine decarboxylase activity (Salford et al., 1994)."

One thing that's not in dispute is that EMF degrades rapidly with distance.  The levels at 3 feet away are often 99% less than the levels at 4 inches away.  So you're getting more EMF radiation from the computer you're reading this on than your light bulb, because you're so much closer to your computer.  Here's a table that shows the levels for various devices at 3 feet and 4 inches away.

That's for EMF in general.  There isn't much research or analysis available about CFL's in particular, but there is this:

1. SCENIHR (an advisory board to European goverments) reviewed the evidence and said that except for people who are extremely sensitive to sunlight (who could develop skin problems from exposure to certain kinds of CFL's), there's no evidence that CFL's cause health problems.
2. Health Canada says "In short, the contribution of the dirty electricity-generated fields to the total produced by CFLs in a home is estimated to be minor or insignificant."
   

Researchers have recently suggested that a special kind of EMF, called "dirty electricity" (DE), is particularly effective at promoting things like cancer and diabetes, and that if earlier research failed to find an EMF / illness connection, it's because that earlier research was looking too broadly at EMF, rather than at DE specifically.  And CFL's are supposedly high in DE.  However, the new research about DE is in its infancy.  I could locate only four studies in peer-reviewed journals about DE, and three of them were by the same author, and none of them was a double-blind case-controlled study (generally considered more reliable than other kinds of studies.)  And Health Canada, as cited above, measured the DE of CFL's and considers it to be very low.  So it's way too premature to claim a definitive link between the DE from CFL's and negative health effects. Of course, that doesn't mean there's no link, only that the science doesn't support confidence in it yet.  I don't fault anyone for wanting to be cautious while the science is progressing.

Anyway, when the experts disagree, I won't presume to be able to tell you the conclusive truth on the matter.  So instead I'll summarize the arguments of both sides.

The case that CFL's are a health risk:

• CFL's emit a much higher EMF than regular light bulbs (incandescents) or the newer LED bulbs.
• CFL's are responsible for a high amount of "dirty electricity" (DE) in particular.
• While few studies exist about DE and harmful health effects (four), all of them found a positive link. (Havas, June 2008,  Havas, Sep. 2008 (PDF), Havas 2006,  Milham 2006, PDF)
  
• If earlier research didn't find links between EMF and health problems, it's because it didn't look at DE specifically.  Therefore, the statements from science organizations that EMF isn't a health risk are unreliable, because they're based on incomplete science.
  
• In any event, there is indeed a fair amount of data linking EMF to health problems, even when the research wasn't DE-specific.
  

The case that CFL's aren't a health risk:

• Most government health organizations say that there is no known risk, including the World Health Organization (EMF in general) and SCENIHR and Health Canada (CFL's in particular).
• Most studies have failed to find a correlation between CFL's and health risks.
• EMF degrades dramatically with distance.  A magnetic field of 6 - 2000 µT at a distance of one inch, is only 0.01 - 0.03 µT at a distance of three feet.(WHO)  If you're not close enough to a household source to touch it, the absorbed EMF is extremely low.
  
• EMF isn't unique to CFL's.  All kinds of electronic equipment emits EMF, including hairdryers, computers, wireless routers, and most notably mobile phones.  So using incandescents instead of CFL's wouldn't necessarily reduce a person's exposure significantly, depending on the kind of electronics in the person's environment.  Even the sun is a source of EMF.
  

• Prevention magazine article on "dirty electricity"
• I'm skeptical of this article because I couldn't verify the claims.  For example, the author says that Gilles Theriault's research on dirty electricity, published in the American Journal of Epidemiology, showed that workers exposed to it had a 15-fold risk of lung cancer.  However, Dr. Theriault's home page lists only one paper in that journal, and that paper says nothing about either dirty electricity or lung cancer.  I found one paper in another journal by Dr. Theriault which addresses lung cancer, but that paper concluded that lung cancer was NOT strongly associated with working in high-exposure jobs.
  
• Popular Science article on electromagnetic hypersensitivity
• Special issue of the science journal Pathophysiology (Aug. 2009), devoted entirely to research on the health effects of EMF (over a dozen articles)
  
• Video interview with Lloyd Morgan, a scientist who believes that cell phones cause brain tumors
  
• EMF documentary: "Full Signal".  Article about the film claiming a clear link between EMF and damaging health effects.  Here's also the home page for the film. 
  

Does bad power factor negate the environmental savings?

No, it doesn't. CFL's do have a bad power factor (50-60%, compared to 100% for regular bulbs), and so some have suggested that the utility company has to generate more electric to power the CFL's, even if the home user isn't charged for it, and so we don't really succeed in burning less fuel at the power plant. The truth is that while low power factor does require the utility to compensate a little bit, it's at a far, far lower level than would be the case if they had to make up the total difference between the actual power factor and a power factor of 1.  For example, here in Austin, Texas our utility is publicly-owned, and they've been aggressively pushing conservation for years to try to prevent having to build an expensive new power plant.  They hand out cold, hard cash for things like recycling your old refrigerator, installing extra attic insulation, putting in solar water heaters, and -- you guessed it -- switching to CFL's.  If CFL's didn't really save electricity even at the power plant then there's no way they'd be doing this.

Dennis Towne, an electrical engineer, agrees that low CFL power factor doesn't negate the energy savings :

"[Bad power factor] causes higher current flow than would be expected for a given power output, but it does NOT increase the power consumed.... [We can now] peacefully ignore the power factor issues of CFL's."

Josey Paul, in a letter to Home Power magazine, also agrees:

"[I]t is not true that utilities must therefore burn twice as much coal or cook twice as many atoms in order to supply twice as much energy to run Carol's CFLs. Power factor does not affect the energy consumption of homes either on or off the grid.... To prove this point, I set up an experiment with CFLs vs. incandescent lights (resistive loads with a power factor of 1.0), and measured watts and volt-amperes delivered by my inverter. Then I measured the amps from my power source, a bank of L-16 batteries, which are DC sources wise to the tricks of reactive power....The low power factor did not require the batteries (or the utility) to produce any extra energy."

Related pages

• My main page on saving energy with lighting
• Questions & Answers about lighting energy