Friday, September 13, 2013

The light bulb myth lives on

I just saw an article in this week's Tip Hero newsletter that kind of got on my nerves. It's one of those ever-popular lists of ways to save on your electric bill that, as I've noted before, seldom have anything to tell me that I haven't heard many, many times before. This article was no exception to that rule, basically trotting out an assortment of chestnuts like "turn off the water when you brush your teeth" and "turn out the lights when you leave a room." The only somewhat new piece of information in it was the recommendation to switch to LED bulbs, and even that was basically an updated version of the traditional recommendation to replace incandescents with CFLs.

There was one detail, however, that particularly annoyed me. In the item on turning out lights when you leave the house or the room, the author of the article made the extravagant claim that this practice "can save you big bucks on your electric bill." Now, even back in the days of incandescent bulbs, leaving lights on was never all that big a waste of energy. If you had a 60-watt bulb, for instance, and you left it burning while you left the room for 15 minutes, then in that time it would use 15 watt-hours, or .015 kilowatt-hours. At the nationwide average electric rate of 12.5 cents per kWh, that's about one-fifth of one penny's worth of electricity. Even if you left that same light on for 15 minutes every single day, the total cost on your electric bill at the end of the month would only come to 5.6 cents. Admittedly, those pennies could add up quickly if you made a habit of leaving all your lights on all the time, and since switching them off was a lot easier to do than, say, upgrading to a more energy-efficient refrigerator, it was a reasonable piece of advice. But even back then, claiming that you could save "big bucks" this way was setting up an unreasonable expectation.

Now, suppose you've followed this author's other piece of advice and started switching over your bulbs to LEDs. A quick Google search shows that an LED bulb equivalent in brightness to a 60-watt incandescent uses 10 watts of energy. So the 5.6 cents you would have saved by switching off that 60-watt incandescent every day for a month is now cut to less than 1 cent. In fact, you could leave a 10-watt LED burning 24/7 for the entire month and it would use only 7.2 kWh of electricity, or 90 cents' worth. There is no possible stretch of the imagination by which that adds up to "big bucks" in savings.

Mind you, I'm not saying that the advice itself is bad. With the price of LEDs now down to as little as $10, this type of bulb has finally become a cost-effective alternative to CFLs, and I will certainly consider one the next time one of my current CFLs burns out. And even if their energy use is low, it still makes sense to turn them out when they're not being used (especially since doing so won't wear them out much faster, as it can with CFLs or incandescents). But promising "big bucks" in energy savings for doing this is simply dishonest.
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