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Fluorescent lights are already efficient when they’re running but I’ve heard that it takes a lot of energy to turn a fluorescent light tube on. So is it more efficient to turn off a fluorescent tube immediately when you’ve finished using it or is it better to leave it on and then wait until you’re more likely to not use it again for a while?

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A fluorescent light uses as much energy getting started as it des to run for 23.3 seconds. In other words, that is a bit of a myth about leaving it on for very long. If you’re going to be in the room and gone for less than 23.3 seconds there’s no point it on, basically. You might as well turn it off because it uses not very much more energy. To put that in comparison, an LED has to run for 1.28 seconds before it uses as much energy. The good old-fashioned incandescent lamp: 0.36 seconds before it’s used as much energy it does running as it does to turn it on.

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Why does the florescent light take so much energy to turn on? –  leongz Dec 7 '12 at 5:30
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@leongz - why not post that as a new question in its own right? –  EnergyNumbers Dec 7 '12 at 7:03
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