BETTER BULB: The compact fluorescent lightbulb is more energy efficient than its incandescent precursor, but is it better to leave it on?
Image: ©GARY ALVIS/ISTOCKPHOTO
-
The Best Science Writing Online 2012
Showcasing more than fifty of the most provocative, original, and significant online essays from 2011, The Best Science Writing Online 2012 will change the way...
Read More »
So you bought a compact fluorescent lightbulb in a bid to be green. Such bulbs are vastly more energy-efficient than traditional incandescents and screw into standard sockets. Should you treat them like their older cousins?
After all, four- and eight-foot- (1.2- and 2.4-meter-) long tubular bulbs common in more institutional settings are sometimes left on permanently, perhaps due to their slow, flickering start-ups. The thinking is that the boost of energy such bulbs require to power up means that it might be best to keep them on when leaving a room, rather than subjecting them to the stress of a restart on your return.
Turns out, however, that power surge is so brief that its energy draw doesn't amount to much: the equivalent of a few seconds or so of normal operation, according to U.S. Department of Energy estimates. In other words, from a strict energy-conservation standpoint, it's almost always beneficial to shut off fluorescents when leaving the room—the start-up energy is offset by the power saved in even the briefest outages.
But what about the wear and tear on the bulb itself? Being too switch-happy reduces the operating life of the lamp, and given that newer fluorescents are still a few times more expensive than old-fashioned incandescents, it makes sense to forestall burnouts. There are also real environmental impacts of their production and disposal to consider.
A simple rule of thumb that balances both concerns is to shut off fluorescents if you’re planning to leave a room for more than five minutes, according to Francis Rubinstein, a staff scientist in the Building Technologies Department at Lawrence Berkeley National Laboratory's Environmental Energy Technologies Division. Mary Beth Gotti, manager of the GE Lighting & Electrical Institute in Cleveland, agrees. For all practical purposes, "it almost always makes sense to turn the lights off," Gotti says. "From an environmental standpoint, the best way to save energy is to turn off the things that you're not using."
Rubinstein notes that, even for fluorescents, the cost of electricity over a bulb's lifetime far outpaces the cost of the bulb itself. "Even if you switch on and off a fluorescent light frequently," he says, "the slight reduction in lamp life is a small effect relative to the energy savings you accomplish by being a good citizen." Gotti adds that the reduction in lamp life from frequent on-and-off switching can often be counterbalanced by the extension of "calendar life"—the actual passage of time between lightbulb replacements—that results from using the bulb for fewer hours.
That sort of calculation will probably become more common as compact fluorescent lightbulbs come down in price, cast more pleasant light and, most importantly, force their power-hungry competitors from store shelves. The Australian government will phase out the sale of traditional incandescents in that country by 2010, and the U.S. Congress has effectively mandated the same ban domestically by 2012. But whereas that new fluorescent bulb is sure to lower utility bills in your home, the real energy-crunch savior has been there all along: the light switch.
* Editor's Note: This is part one of a two-part series of Fact or Fiction? on fluorescent lightbulbs. The next, appearing on April 10, will address the question of the mercury inside them.
See what we're tweeting about
25 Comments
Add CommentMYTHBUSTERS did this 2 years ago. You guys need to catch up.
Reply | Report Abuse | Link to thisLED technology is coming online at an increasing rate. I predict that is the next energy saver. They do not have the lumens that normal bulbs do and they are expensive but I expect technology to change.
Reply | Report Abuse | Link to thisAs "cribcat" already said, LED's illumination is easier to handle, and I believe too that will be the next energy saver.
Reply | Report Abuse | Link to thisLED's are becoming cheaper and we also have the facility to incorporate other technologies with them, such as Infrared to Internet connection for instance.
The photo accompanying the article is well done - the bulb appears to be glowing, but it's not plugged in.
Reply | Report Abuse | Link to thisBut is it energy efficient anyway? I have 15W florescent bulbs that take 60VA. Yes i pay for (i hope) the 15W or real power but the utility company has to generate and supply the 60VA.
Reply | Report Abuse | Link to thisThese green bulbs are just hiding the real problem. Maybe we should all pay for VARs not Watts !
I have 48 CFL's installed in and around my home. I've had some for over six years. They do provide just as much light (lumens) as incandescent bulbs. In Canada, we can buy them in six packs on occasional sales for $1.50 each. We seem to have a wider selection of better quality bulbs at lower prices than are available in the U.S.
Reply | Report Abuse | Link to thisTurning these bulbs off may save electricity, however, the mandatory transition to flourescent bulbs may not be the energy saver that it has been made to look like.
Reply | Report Abuse | Link to thisA recent article in the [url http://www.thestar.com/article/346692] Toronto Star[/url] talks about the fact that in colder areas incandescent bulbs are actually not wasting as much energy as is thought in the cold months. In these areas much of the "wasted" energy actually goes towards heating homes.
So the recommendation is to use flourescent in warm climates and summer months. However, in cold climates, it would be optimal to energy savings if everyone would switch back to incandescents in the winter time. Obviously there are some places that it would not be wise to do so (ex. outdoors, a restaurants kitchen, ...).
So I guess my conclusion is that further evidence should be gathered before outright banning of incandescents
--
Edited by the-mr-nf at 03/29/2008 6:56 PM
I'm curious about the environmental impact & cost we've assumed by sprinkling the country side w/ small glass containersw w/ a wee bit of Mercury in them.
Reply | Report Abuse | Link to thisMy opinion is that the governments of the world should push with an all out effort to incorporate LEDs fully into our society in virtually all of our lighting needs. On this issue I have written a few articles to voice my opinions.
Reply | Report Abuse | Link to thishttp://www.quazen.com/Science/Environment/Led-Lighting-The-Worlds-Final-Frontier.17178
Led Lighting: The World's Final Frontier
http://www.quazen.com/Science/LEDs,-The-Future-Of-Global-Lighting.15042
LEDs, The Future Of Global Lighting
http://www.quazen.com/Science/Environment/The-Incandescent-Light-It-Must-Go.17579
The Incandescent Light, It Must Go!
I believe it obviously makes sense to turn the lights off when leaving a room for even a minute, in research settings. You are usually being preoccupied with other things and won't return for awhile. But on the other hand, the government usually covers the cost and it makes it more convenient to leave them on. The real question is how about the computers that are left on all day and the hplc's in my case (high performance liquid chromotagraphy).
Reply | Report Abuse | Link to thisThe calculation depends on whether it is winter or summer. In summer, the waste is about 3x because A/C has to be used to counter the heat produced. In winter, not a problem because heating has to be done anyway and turning off the lights just means that the heating source works harder.
Reply | Report Abuse | Link to thisI don't do guestimate/estimates. I have been doing energy studies on these devices for years. Turn one on and you will find that a few seconds runs from 20seconds to a minute. Now take a reading on the start circuit, multiply that by amperage and you have a tremendous surge in BILLABLE POWER. The commulative KWs can be and usually are very expensive. I just left a location where the KW rate is almost 30 cents. Ignorance is a very expensive luxury. Further and finally, the mercury in these devices, even single appliances can cost up to $1,000/per spill to contain. Now imagine millions of these devices crushed and bleading mercury into your local aquafier. The people making these statements of ignorance need to be curbed. These devices are not cheap, cost effective, or safe. They are a plague of ignorance upon our children's house.
Reply | Report Abuse | Link to thisTSS
tssstein@yahoo.com
Another thought on savings: recently I kept track of two compact fluorescent lamps, one of 13 watts, one of 14watts, which ended their lifetimes well over their rated 10,000 hours. The 13 watt (24VA) lamp lasted 16,720 hours in continuous commercial hallway use. The 14 watt (27VA) lamp lasted 35,784 hours in continuous use. These lamps were in use in Canada in an indoor heated hallway. The fact that they contain mercury was NOT mentioned on them. Newer recently purchased compact fluorescent lamps DO mention the mercury. Disposal of older lamps without the mercury warning has probably already taken place in landfills, and should be of concern to all of us on the planet, especially in the developing world where proper disposal facilities do not exist. Most places in Canada do have some form of proper disposal available.
Reply | Report Abuse | Link to thisDoes Compact fluorescent lightbulb cause visible damages to the face skin, similar to sunburns?
Reply | Report Abuse | Link to thisDo compact fluorescent lightbulbs cause visible damages to the face skin, similar to sunburns?
Reply | Report Abuse | Link to thisI am replacing incandescent bulbs as they burn out with compact fluorescent lamps. With about 60% of the incandescents replaced today, I expect that before I reach 100% replacement, LED's will start to replace compact fluorescent lamps.
Reply | Report Abuse | Link to thisI'm having trouble with the notion that it's OK to leave a trail of mercury. Is this the best answer we have to be green and conserve energy? I hope this is merely a transitional technology.
Reply | Report Abuse | Link to thisMy Ikea, Philips, and Sylvania bulbs all seemed prone to early failure. Very disappointing. Now trying Springlight- any comments?
Reply | Report Abuse | Link to thisI echo the comments of MR-NF. In cold climates incandescent bulbs are in effect co-gen units producing light and heat. In many jurisdictions such as Ontario or Quebec where electricity is produced by non fossil sources, this amounts to carbon free heating. Ban the use of incandescents, and this lost heat will be made up by harder working furnaces that are almost exclusively fossil powered. Let economics bring about the demise of the incandescent, not well meaning but flawed government fiats.
Reply | Report Abuse | Link to thisI echo the comments of MR-NF. In cold climates incandescent bulbs are in effect co-gen units producing light and heat. In many jurisdictions such as Ontario or Quebec where electricity is produced by non fossil sources, this amounts to carbon free heating. Ban the use of incandescents, and this lost heat will be made up by harder working furnaces that are almost exclusively fossil powered. Let economics bring about the demise of the incandescent, not well meaning but misguided laws.
Reply | Report Abuse | Link to this"A recent article in the [url http://www.thestar.com/article/346692] Toronto Star[/url] talks about the fact that in colder areas incandescent bulbs are actually not wasting as much energy as is thought in the cold months. In these areas much of the "wasted" energy actually goes towards heating homes."
Reply | Report Abuse | Link to thisIt's true: incandescent bulbs do put out heat. The problem is that they aren't designed to heat a home, and the amount of heat they emit is minimal compared to the electricity they require. Don't count on incandescents to heat your home!
Mythbusters are cowboys -- ex-stuntmen who wouldn't know careful scientific methods if they hit them in their faces. Remember, this show is for entertainment only -- zny resemblance to science is purely coincidental.
Reply | Report Abuse | Link to thisdoes anyone know the diff between a t8 and a t12 48" bulb,besides the size
Reply | Report Abuse | Link to thiscan you use a t8 ina light that already has a t12 and viceversa
thanks
CFL's do not work well in cold conditions, and should not be used with emergency lighting systems as most do not work with the back up battery power. As some bulbs do not become efficient and reach 80% brightness until 5 minutes after being turned on, be very careful in what type of CFL's that you buy. A light for a closet or bathroom needs to come on immediately!
Reply | Report Abuse | Link to thisOutlawing incancesdents seems silly until we know what is best for the uses that CFL's do not fill.
I am doing an enery audit with my students for our school. Several (30-100) florescent bulbs are dead(not turning on, need replaced )but their ballasts are very warm. Do "dead" bulbs draw power and if so at the same rate or more than bulbs attached to the same fixture that are working?
Reply | Report Abuse | Link to thisMother Nature