Is it less expensive to leave lights on all the time, rather than turning them on and off?

A common myth about lighting system is that it is more expensive to turn lights on and off, so it's better to just leave lights all the time. Not true! Fifty or sixty years ago, when lamps were expensive and electricity was inexpensive, that may be true. Times have changed, and now lamps are relatively inexpensive and electricity is expensive.

It is true that turning lamps on and off many times a day can shorten the lamp life. In extreme cases, that cost of having to buy more lamps may offset the energy savings. What's the situation at UNH?

Incadescent lamps are so inefficient, it always pays to turn them off when they're not needed, even for very short periods of time. For flourescent lamps, the breakeven point is about five minutes. In other words, if fluorescent lights will be off for five mintues or longer, it's more cost effective to turn them off than to leave them on.

It is understandable that some people leave their lights on to let others know that they are in the building. We are considering the possibility of providing doorknob hanger signs with wording such as: "I'm in the building, but my lights are off to save energy. I'll be back soon." Let us know what you think about that idea.

Now that the lighting myth has been debunked and we see how much energy is being wasted, what are your thoughts on why so many lights are left on in empty rooms? We need your comments and suggestions.

Please remember to turn out the lights when you leave your room or office.

If students aren't waithing outside for the next class period, turn out classroom lights when you leave. Use fluorescent lamps instead of incadescent lamps whenever possible. (For every dollar spent on electricity for an incadescent lamp, you only receive 15 cents worth of visible light.)

Remember that halogen lamps are incadescent lamps.. use fluorescent lamps instead of halogen lamps whenever possible.