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Watts into Watt-hours

  1. Jul 9, 2010 #1
    I have a survey with data on electricity consumption per month in Watts. How can I convert the numbers into Watt-hours to compare it with another survey?
    Thank you very much for your help.
    Best,
    Marianne
     
  2. jcsd
  3. Jul 9, 2010 #2

    jtbell

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    Staff: Mentor

    Assuming the watts figures are the average number of watts over an entire month, then the number of watt-hours is the number of watts times the number of hours (in a month).
     
  4. Jul 9, 2010 #3

    russ_watters

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    Hmm......I'm guessing the data is periodic recordings of the instantaneous wattage. If that's the case, then each must be multiplied by the time between recordings and then they must be added together (or vice versa) to get the total consumption for the month. For example, if the data looks like this:

    12:00 10W
    12:15 15W
    12:30 12W
    12:45 11W

    Then the total consumption is (10+15+12+11)*.25hr = 12 W-hr.

    This can easily be done with a spreadsheet.
     
  5. Jul 9, 2010 #4
    Thank you for your answers.
    I am actually using a household survey of Kenya. The question is:
    During the last month how many watts of electricity did you use?
    How can I use this number? If I multiply it by 24*365, the total result over the sum of all households is higher than the number in the sales statistics of the national electricity company.
     
  6. Jul 9, 2010 #5

    jtbell

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    That question is probably too vague to give useful results, unless the respondents were given more detailed instructions. I suspect most people would give the total wattage of all their appliances. But many appliances are used only intermittently for short periods of time. Exceptions would be things like refrigerators which run continuously. Even light bulbs are not usually turned on 24 hours a day. Some people might try to correct for this, but you can't count on them all doing it similarly.
     
  7. Jul 9, 2010 #6

    russ_watters

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    If that's the question, it isn't vague, it's wrong. The units don't match the question. So either the question has been translated incorrectly or the survey was done wrong in the first place. If you ask 100 people that question, I suspect 90 of them will just read you the W-h number on their electric bill, but that just means that some people gave you one kind of data and some gave you another.

    I'd try to see if you can get the question and the methodology clarified.
    You may also be able to tell from the data itself if it is really in watts or watt-hours. What happens if you multiply the number by 12...?
     
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