Martin Lewis's energy calculations

Sterlingtimes
Sterlingtimes Posts: 2,390 Forumite
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I think how Martin Lewis and the Centre for Sustainable Energy calculate energy usage is misleading. Notwithstanding his use of watts to equate to watt-hours, a washing machine using a peak power of 2,100 watts is unlikely to use 2,100 watt hours per cycle. 

A cotton cycle for a 10 kg load set at 40 degrees and 1600 RPM spin is unlikely to use more than 1 kWh of energy per cycle. Therefore two cycles a week would use 104 kWh in a year. Even at 37p per kWh, the annual running cost would be £38.


I have osteoarthritis in my hands so I speak my messages into a microphone using Dragon. Some people make "typos" but I often make "speakos".
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  • MultiFuelBurner
    MultiFuelBurner Posts: 2,928 Forumite
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    I think how Martin Lewis and the Centre for Sustainable Energy calculate energy usage is misleading. Notwithstanding his use of watts to equate to watt-hours, a washing machine using a peak power of 2,100 watts is unlikely to use 2,100 watt hours per cycle. 

    A cotton cycle for a 10 kg load set at 40 degrees and 1600 RPM spin is unlikely to use more than 1 kWh of energy per cycle. Therefore two cycles a week would use 104 kWh in a year. Even at 37p per kWh, the annual running cost would be £38.



    I might suggest many don't run the latest energy efficient models.

    Ours too doesn't use more than 1kwh for a 40oC wash but it's a fairly new Bosch.
  • Bendo
    Bendo Posts: 291 Forumite
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    This is the cycles summary for my machine. I'd struggle to get those power consumptions. Maybe if I did a few washes...
  • Gerry1
    Gerry1 Posts: 9,936 Forumite
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    edited 20 February at 8:21PM
    Yup, it's a well-meaning but quite muddled site.  They often confuse energy with power, similarly kWh with kW, with clangers like these:-
    ★ 'It will use 12kWh of electricity (e.g. half a kilowatt every hour).'
    ★ 'sometimes a higher-wattage appliance will actually use less power overall than a lower-wattage one'
    ★ Even on the same page they have calculations based on a mixture of old and new kWh rates.
    ★ They think a fan heater is a 'radiant' type.
    ★ They confuse plugs and sockets.
    ★ Also a bit daft to classify an iron as high consumption.  Technically true, but far less of a problem than using plug-in electric heaters every day for long periods.
  • MeteredOut
    MeteredOut Posts: 1,255 Forumite
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    "I think how Martin Lewis and the Centre for Sustainable Energy calculate energy usage is misleading."

    I doubt Martin Lewis has even read that piece, never mind been involved in its authoring. It was clearly written by someone who didn't really understand what they were writing, however.
  • Sterlingtimes
    Sterlingtimes Posts: 2,390 Forumite
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    "I think how Martin Lewis and the Centre for Sustainable Energy calculate energy usage is misleading."

    I doubt Martin Lewis has even read that piece, never mind been involved in its authoring. It was clearly written by someone who didn't really understand what they were writing, however.
    A source is here:

    Martin Lewis reveals simple way to calculate running cost of any household appliance | The Sun


    I have osteoarthritis in my hands so I speak my messages into a microphone using Dragon. Some people make "typos" but I often make "speakos".
  • Bendo
    Bendo Posts: 291 Forumite
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    The Scum. Well known for fine journalism and accurate direct quotes.
  • MeteredOut
    MeteredOut Posts: 1,255 Forumite
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    edited 21 February at 2:13PM
    The only quote from Martin Lewis is

    "So 100W (a tenth of a kW) appliance on for two hours is 3.4p an hour x 2 = 6.8p," he said.

    Which is factually correct. 

    The full tweet is here:


    and if you check the responses, people have raised the same point you did regarding items not drawing a constant load, to which he agreed.

    The rest of that is just the The Sun, well, being The Sun and putting words onto a page as click-bait. In this case, using Martin Lewis's face as hook to get clicks.

    "Using Martin's calculation, The Sun has crunched the numbers on how much costs to run a number of common household appliances."

    It really is just the usual sub-standard journalism we should have come to expect from that outlet.

  • Sterlingtimes
    Sterlingtimes Posts: 2,390 Forumite
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    The only quote from Martin Lewis is

    "So 100W (a tenth of a kW) appliance on for two hours is 3.4p an hour x 2 = 6.8p," he said.

    Which is factually correct. 
    Thank you for the Tweet and for taking the time to post. You are correct.
    I have osteoarthritis in my hands so I speak my messages into a microphone using Dragon. Some people make "typos" but I often make "speakos".
  • Sterlingtimes
    Sterlingtimes Posts: 2,390 Forumite
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    Bendo said:
    This is the cycles summary for my machine. I'd struggle to get those power consumptions. Maybe if I did a few washes...
    Thank you, Bendo. That is interesting. A category C machine like mine would sit close to 1Kwh for a Cotton 2 wash. Your older machine appears to use about x1.4 energy.
    I have osteoarthritis in my hands so I speak my messages into a microphone using Dragon. Some people make "typos" but I often make "speakos".
  • Bendo
    Bendo Posts: 291 Forumite
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    Bendo said:
    This is the cycles summary for my machine. I'd struggle to get those power consumptions. Maybe if I did a few washes...
    Thank you, Bendo. That is interesting. A category C machine like mine would sit close to 1Kwh for a Cotton 2 wash. Your older machine appears to use about x1.4 energy.

    Oddly it's brand new (otherwise the program cycle list would have long since made its way to the recycling bin).

    It's a B rated 9kg Hotpoint. Wouldn't have been my first choice to be fair but selected purely on the basis of it's height due to the kitchen fitters incompetence in not taking into account the height of the floor tiles....


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