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I keep hearing this argument that if you powered down all the appliances you normally leave on standby (TV, hifi, set top box, DVD/Blu ray player, computer, etc) you'll save nearly £90 a year in electricity bills.

However, the table in the linked article claims 10 watts as the standby power of a typical TV. My understanding is that EU regulations limit TV power consumption in standby mode to 1 watt maximum so I decided to do a little digging. My TV is an old 50 inch plasma, which I know guzzles electricity when powered up, but I never suspected it of using a great deal of power when in standby. As confirmed by the specs, it uses 1 watt in standby as opposed to 10 as claimed in the This Is Money article. I've not checked the specs of other appliances on that list yet but given the results for my power-hungry TV I think the rest of the figures are highly questionable as well.

Yet the advice I keep hearing advocates turning appliances completely off instead of leaving them in standby. This advices gets trotted out on fairly regular intervals by the national papers (as recently as today). My power supplier also makes similar suggestions along with replacing bulbs with energy saving bulbs, which does seem a reasonable measure as the house I recently moved into was outfitted with 8x50 watt halogen spotlights in the kitchen and I've not noticed any real downside to replacing them with equivalent LED bulbs that use 5.5 watts. 44 watts to light the kitchen versus 400 seems like a pretty significant win.

Yet, no matter how often I hear this advice I remain unconvinced. Can you really save £90 a year by turning everything completely off instead of leaving it all in standby, or are the figures vastly inflated for other products as they turned out to be for my TV?

If you can't make significant savings this way, then what do the power companies, etc, have to gain by continuing to circulate advice that (if the figures for all appliances have been inflated by a factor of 10) would save you a tenner a year at best? I could speculate on possible motives (getting us all to agree to having smart meters installed, trying to put off investment in power plants and national grid as long as possible, shifting the blame unto us if/when power supply starts to become constrained in the future, etc), but levelling accusations of that nature feels like falling foul of conspiracy-theorist thinking.

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    That "This is Money" article is quite wonky: "look on the back of the appliance [...] where it will specify the electricity demand figure in watts (W) or kilo watts (kW). [...] Then multiply the kW figure by the rate of electricity you are currently paying in pennies. You can then multiply that by the true amount of hours you have your appliances on standby to give a better reflection on your annual saving, if you were to turn everything off at the mains." So they say to use peak power consumption as the base line, not standby. – Ken Y-N Sep 26 '14 at 1:11
  • Thanks. I'm aware that that particular article is questionable, but the question was about the advice in general which keeps cropping up over and over. Is there anything to that advice or is it questionable? – GordonM Sep 26 '14 at 7:00
  • I recently measured my work PC to be drawing 8W when OFF, without the monitors. – Vorac Sep 29 '14 at 8:23
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Answer: Yes, you can save that much.

£90 really isn't that much over the course of a year - about 25 pence per day.

According to this website

The price of electricity in the UK in 2013 averages 17.2 pence per kWh

That means over the course of one day, you need to save 1.45 kWh (kilowatt hours) in order to save 25 pence. You can accomplish that by reducing your average energy consumption by 60 watts. According to these numbers, having switched those lights from 400 watts total to 44 watts total should be saving you over £500 each year.

This nice table shows the power consumption of different devices while in sleep or standby modes. In particular, they found that a desktop computer uses 21.13 watts while in sleep mode compared to 2.84 while off. If you happen to have three desktop computers, then turning them all off will just about get you to the 60 watts needed to save £90.

Because of the variability in power consumption between the various types of devices, how much money you can save will obviously depend on what devices you have, but it does not take too many devices to be able to reduce power consumption by 60 watts.

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    It's worth thinking about how much time you'd spend unplugging and plugging in devices, though. For things you rarely use, it is definitely worth it to unplug it when not using it. For things you use frequently, your time may be more valuable to you than what you would save on your power bill. – Rob Watts Sep 25 '14 at 19:39
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    I don't think that table and your quote is really useful. @GordonM asked about domestic appliances, not computers, and his example of TVs gives an average of 5W, half the 10W that he is questioning. – Ken Y-N Sep 26 '14 at 1:13
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    2.84 watts while off? Aside from a real time clock (which runs off a backup battery and would be poorly designed to say the least if it was drawing more than milliwatts) what power draw would a computer that was completely powered down have? – GordonM Sep 26 '14 at 7:03
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    It is worth noting, that even if turning off an appliance might be a trivial cost saving (which is not in general), the compound effect of millions of people doing the same has significant effect on power consumption and greenhouse effects and all that! – Nikos M. Sep 30 '14 at 23:02
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    @GordonM Some components stay on even when the computer is "fully" shut down but still plugged in. The network card, for example, remains partially on because computers have a feature that allow them to be turned on remotely. I am not sure what the full list of power-use is for the "off" PC, and depends on the specific PC itself, but they do use power. I have no idea how much power though. – Aaron Jul 17 '17 at 20:10

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