Sunday, May 31, 2015

Blinded by Science blog 7: Do you really save any electricity and money by unplugging household devices when they are not in use?


Good day fellow humans.  It is I, your host, back for another tony edition of Blinded by Science.  And yes, you read that right, back for another TONY edition.  My name is actually an adjective meaning high-toned or stylish!  And as we all know, our names are permanent reminders used to fully describe who and what we are.

Who shall I be today?

Or not . . .

Anyway, today I will be answering a question from Steve P.  He asks, “Do you really save any electricity and money by unplugging household devices when they are not in use?”  Well Steve, this question reminds me of another question I have answered.  It turns out I was used as part of an ongoing marital argument when I answered that previous question so I hope that this is not the case now.  And if it is, I expect pay commiserate with the risk I am taking by getting involved.  I accept personal checks, cash, gift cards to delicious restaurants, and chocolate.

So now, let us get into today’s question.  Steve, the answer to your question is yes, unplugging electronics when they are not in use will save electricity and therefore money.  Though there is a caveat (when in life isn’t there?).  This only holds true for certain types of household devices – those that use standby power.  But what is standby power?  It is “electricity used by appliances and equipment while they are switched off or not performing their primary function.  In other words, it is electricity that devices use when they are not in use.  Simple example, the little LED light on the front of the television that glows red when the TV is turned off (it changes color when you use the remote to turn the TV on).  It takes electricity for the light to be on, even though you have turned the TV off.  As another example, look at your microwave.  Even when the microwave is not in use, it uses electricity to keep the clock running.

The amount of electricity these appliances use is usually rather low.  According to studies done by Lawrence Berkeley National Laboratory, the majority of devices with standby power tested use less than 10 watts of electricity.  But having multiple devices in your home that use standby power can add up.

Let’s assume that the average device with standby power consumes 5 watts of electricity.  To convert that number into kilowatt hours (unit of energy consumption utilized by electric companies to determine cost) we must first multiply it by the number of hours that the device is on.  In one year there are roughly 8760 hours (24 x 365) that this device is drawing power.  So 5 x 8760 equals 43800 watt hours or 43.8 kilowatt hours.  The average price of residential electricity in the United States in March of 2015 is 12.35 cents per kilowatt hour.  So the average device with standby power costs a homeowner roughly $5.41 per year (43.8 kilowatt hours per year x 12.35 cents per kilowatt hour equals 540.93 cents per year).  That’s not too bad.  Unplugging this device permanently would basically allow you to have one more fast food dinner a year.  If the average house has forty of these devices, the cost then becomes roughly $216.37.  So unplugging these devices would save you quite a bit of money over the year which could be spent on other necessities.

Or a number of extra fast food meals

With that said, this only applies to devices that use standby power.  Electricity does not flow when an electrical circuit is not completed (think about how cars don’t move during a traffic jam because both lanes of a highway are blocked) so other devices, like lamps, that aren’t drawing electricity when turned off don’t need to be unplugged.  Also, you shouldn’t unplug all devices that use standby power either.  Refrigerators use standby power so they can continuously monitor the internal temperature and switch on when it gets to a certain point.  Unplugging a refrigerator would be a bad idea.

Nothing wrong here.  Just wipe it a bit and everything will be as good as new.  And delicious.

Well, I hope I’ve been able to help.  Tune in next time when I answer another of your burning science questions!

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