A lot of people wonder about turning fluorescent lights on and off. Fluorescent lights have a lifetime related to the number of times they are turned on and off, and it takes additional energy to turn a fluorescent light on (though not as much as most people think). This leads people to wonder what the best energy/bulb-lifetime strategy is for fluorescent bulbs: should they be left on or is it better to turn fluorescent bulbs off and and when you go out of/into a room?

The answer is this: If you are leaving a room for more than 15 minutes, turn the fluorescent lights off. If you are leaving a room for less than 15 minutes, leave the fluorescent lights on.

If you are interested in the nitty-gritty details concerning the energy efficiency of fluorescent lights and how turning them on and off affects their lifetime, you can find the details at the link below.