When to Turn Off Fluorescent Lights
As more and more homes have compact fluorescent lights, questions are arising about when (or even whether) they should be turned off. One school of thought is that it takes a huge surge of electricity to start fluorescent lights (like those institutional tubes in your 6th grade classroom), and turning the lights on and off actually uses much more electricity than just turning them off when you are out of a room for a while.
In a word: WRONG!
As a good rule of thumb, if you don’t need the light for five minutes or more, turn it off.
The energy needed to start a fluorescent light, whether a compact fluorescent or a traditional, linear tube, is slightly higher than what it needs for continuous operation once it has started, but only slightly so. According to the US Department of Energy, it is the equivalent of just a few seconds of operation. So in almost any instance, from an energy savings perspective, it makes sense to turn it off.
The other consideration is the life of the bulb itself. There is some stress placed on a fluorescent light every time it starts up. A fluorescent light that is repeatedly turned off and on will, on average, have a shorter life than one that is constantly lit. But while this is a consideration, it isn’t the most important one.
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 a fluorescent light on and off 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.
One of the biggest complaints with some compact fluorescent bulbs is that they only have a fair color rendering index, and are even poorer when they first start. If color accuracy is an issue, it may make sense in certain cases to leave the lights on a little longer, but generally, compact fluorescent lights reach their full output after just a brief time.
Replacing inefficient incandescents with compact fluorescents can help, but the small measure they represent shouldn’t be mistaken for solving the whole problem. While compact fluorescents are the poster child for energy savings, other home equipment like heating and cooling equipment and water heaters have more impact on the overall energy usage of a home.
via: Scientific American
As someone who sells light bulbs for a living, I am less enthusiastic than most about compact fluorescent bulbs. This is due to the fact that the ones currently available contain significant amounts of mercury. If one of these bulbs should break inside of a person’s home, it could cause a challenging disposal situation. It is my belief that the technology should progress to a point at which the mercury levels are low or nonexistent before people changeover their entire homes. Another consideration is that as these bulbs burn out, they will most likely be thrown away as though they are normal rubbish and landfills will have incredibly high levels of mercury in their soil as a result.
What do you define as “significant amounts of mercury”? Does the fact that several times as much mercury is dumped into the environment from coal burning to provide the extra electricity to operate incandescent bulbs not register as “significant”?
Calling it “a challenging disposal situation” is alarmist and unhelpful. See Snopes or EPA for more reasonable explanation of broken CFL cleanup:
http://www.snopes.com/medical/toxins/cfl.asp
http://www.energystar.gov/ia/partners/promotions/change_light/downloads/Fact_Sheet_Mercury.pdf
More people need to be aware of recycling options for CFLs (and more places need to provide it) so it becomes more widely recognized and more convenient. But that’s no argument for not using them now.
Good article - the Mythbusters on the Discovery Channel (episode 69) also busted the myth of leaving lights on (incandescent, CFLs and others) in a room if you’re only going to be gone for a short period of time.
“Based on the amount of energy consumed turning on the bulb, they were able calculated how long the bulb would have to be turned off in order to make it worth the energy savings, i.e. “It’s best to turn off the bulb if you are leaving the room for”:
* Incandescent: 0.36 seconds
* CFL: 0.015 seconds
* Halogen: .51 seconds
* LED: 1.28 seconds
* Fluorescent: 23.3 seconds”
http://kwc.org/mythbusters/2006/12/episode_69_22000_foot_fall_lig.html
Most CFLs today on the market contain less than 5mgs of mercury and there are CFL options out there that contain as little as 1.5mgs of mercury- which can hardly be called a “significant amounts of mercury” considering that many item in your home contain 100s of times more of mercury including your computer. Mercury levels in CFLs can never be “nonexistent” since mercury is a necessary component of a CFL and there is no other known element that is capable of replacing it. But CFLs actually prevent more mercury from entering the environment. According to the Union of Concerned Scientist, “a coal-fired power plant will emit about four times more mercury to keep an incandescent bulb glowing, compared with a CFL of the same light output”.
I find that these compact CFLs constantly are breaking. I also have noticed that I can get mental fatigue from this type of lighting.
I am curious what you are doing that you are “constantly breaking” CFLs.
In fact, in any application, if you’re constantly breaking bulbs, I’d think that something else was wrong.
Okay - for the real answer see
http://mythbusters-wiki.discovery.com/page/Lights+On+or+Off%3F
Now you have the real answer.