Conclusion: BUSTED.
So, should you keep the light on in a room if you're leaving it and know you’ll be back again in a few minutes?
Truth: The answer is an unequivocal no. According to the California Energy Commission, the energy used in the fraction of a second it takes to turn a light bulb on is negligible compared to the amount of energy it takes to keep a steady glow. That goes for fluorescent and incandescent bulbs.
Have a friend who swears turning off the light when you leave a room actually wastes energy? Does your uncle tell you Hummers are more eco-friendly than hybrids? Whatever the eco myth, we'll help you get to the bottom of it. Submit your myth to SustainLane Greenbusters.
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James E. says:
Now, I'm pretty sure I read somewhere that turning the light on and off actually shortens its life because of the surge of power to the bulb when the lights are turned backed on, and this would be for conventional lighting. I have no idea how you'd calculate the trade-off between saving power, and using more bulbs, if indeed that was the case, but it is an example of the myriad ways to look at all this stuff. The solution I like the best is one of the Green Building Councils maxims...use daylighting whenever possible...natural light is better for our health, and uses neither power nor bulbs :-)
Adam W. says:
James,
You make a good point - there are SO many different ways to look at a situation. It is for this exact reason that many of these myths come about in the first place. Here are two great link that deal with lighbulbs:
This is the mythbuster episode in which they test this exact myth:
http://www.sustainlane.com/reviews/mythbusters-take-on-lightbulb-energy-myths/2IXDCB3S72RNY2NAFJT87HQ72U9S?dspm=aptu
Here is a page with a bunch of lightbulb facts: http://members.misty.com/don/bulb1.html
Essentially, here is the way it works. As the Greenbusters show above, turning on a light requires a surge of energy, but that energy is equivalent to less than 1 second of leaving that lightbulb on - this stands true for burning out the filaments as well. Filament slowly burns up over time as a light bulb burns, and more of it burns up on startup. However, the amount that burns up on startup is not significantly more than burns up when leaving a bulb on - again, it is worth less than a second of leaving your bulb burning.
I have to admit I am slightly worried about some of these myths. I feel like most Americans (and most people in general for that matter) want to do the right thing. The problem is, most people [obviously not me :)] have no time to look up all the facts behind these myths. As soon as they hear that there are two sides to the issue, they go back to doing whatever is easiest for convenience sake. While there is often a grain of truth in these myths (for instance, that Prius's take more energy than regular cars to manufacture) 99% of them are false in the end (like the claim that a Hummer is actually greener than a Prius because of the initial Prius energy requirement).
My advice - KEEP IT SIMPLE. Look at a situation and see what makes the most sense upon first observance. The chances are pretty good that when all of the other little things are taken into account, your initial reaction will be the right one.
Chris J. says:
Adam, that Mythbusters video is awesome! I thought they very thoroughly addressed and debunked the "myth".
Suzan W. says:
Adam, I am glad you do have the time to look these thing up and enlighten those of us who are clearly misinformed. I had always thought that florescent lights used more energy to turn on than to leave on for short time and have been leaving them on when I leave the room knowing I'll be back within minutes. Thanks for correcting me!