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Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
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    • CommentAuthorbarge17
    • CommentTimeJan 25th 2016
    Every Month, and sometimes at closer intervals, I record our 3 electric meters, gas meter, and water meter on a spreadsheet. Then I mess about copying and pasting a row of formulas to give me the consumption.

    I have been looking for some time for a ready made spreadsheet which can make a few charts from my data, but the thing that I realy can't sort myself (brain fade) is to make it possible to read the meters on any day day of the month to give better resolution of the graph if we are running the log boiler more or less than usual.

    I wonder if there is anything out there that can be adapted for my purposes?

    • CommentAuthorrhamdu
    • CommentTimeJan 26th 2016
    I never read the meters repeatably on an exact day. I am just not that organised. Instead, I calculate kWh/day for any period by taking the difference between the two meter readings and dividing that by the number of days between the reading dates (just subtract the dates to get this).

    It means I can't do exact year-on-year comparisons. I might be comparing 10 October to 15 March in one winter to 18 October to 12 March in another. But it's near enough.

    I'm not clear about the woodburner issue. Is it that you want to measure energy use at times when the log boiler is not in use? In that case I don't see anything for it: to get anything near complete data you will have to read meters before and after every burn. Or have I misunderstood?

    It will be difficult to calculate how much electricity and gas you are saving by using the log boiler, because you can only guess how much you would have used without it. You could estimate the saving by comparing days with similar weather conditions, with and without the log boiler. OK in theory, difficult in practice I suspect.
    • CommentAuthorbarge17
    • CommentTimeJan 26th 2016
    "about the woodburner issue. Is it that you want to measure energy use at times when the log boiler is not in use? In that case I don't see anything for it: to get anything near complete data you will have to read meters before and after every burn."

    Yes, that is exactly what I do with the gas meter, but my problem is dividing the readings by the number of days automatically and then getting a graph out of it, the electric and water meters are another matter and could be on a separate spreadsheet.

    • CommentAuthormike7
    • CommentTimeJan 26th 2016
    From one faded brain to another... I did sort out an xl spreadsheet to do roughly what you're after. I don't know how to get it to you via this forum, but maybe you could whisper me your email and it could go that way. Graph may appear:-
    • CommentAuthorrhamdu
    • CommentTimeJan 26th 2016
    Mike's graph looks good. One way or another you need to get the dates of readings, and not just their sequence, onto the x axis. Then time will appear to flow steadily however many or few readings you take - if you see what I mean.
    • CommentAuthormike7
    • CommentTimeJan 26th 2016 edited
    Thanks rhamdu - but my graph is a bit misleading really. For each time interval I get the average usage for that time, and the graph plots that as just one point at the date of the end of the interval. What would be better is for it to plot a bar chart with each bar's width equating to the time interval, and the bar's height equating to the average. How to do this in xl was beyond human understanding, or the bit of it I have left anyway.
    • CommentAuthorbarge17
    • CommentTimeJan 26th 2016
    Thank you both, if I get the spreadsheet, I shall then see how it treats dates as a number, then I shall try it for a month per page of the graph and see if I can remember to record the Gas meter reading every day. If it can somehow do averages for missed reading days that will be a good do.

    Then I might begin to get a better picture of the gas usage compared to volume of wood burnt.
    • CommentAuthorvord
    • CommentTimeJan 27th 2016
    If you use Excel and format the date column as date then it will be possible to subtract dates from eachother.
    So (kW/h_2-kWh_1)/(date_2-date_1) Plot the result against date on an XY scatter plot.
    • CommentAuthorbarge17
    • CommentTimeJan 27th 2016
    Thanks for the spreadsheet and your help, I shall report back when I have got something to show ( might be some time :-) )
    • CommentTimeFeb 1st 2016 edited
    Dates are treat as whole number. 1 is equal to 1 day, 2 is equal to 2 days.
    Today's date as a number is 42401
    Tomorrows will be 42402
    Day 1 was 01/01/1900 in Excel (default settings using Windows 8.1).
    So normal addition/subtraction works for dates.

    You could estimate the energy input from the wood burner by weighing the timber you burn.
    Make a big pile of it, weigh it, burn for a week/month/whatever, then weigh the remains.
    Or you could just get an energy monitor and logger (my favourite manufacturer is no longer in existence).

    It is easy to get local weather data, Met Office or WeatherUnderground. You can download historic data from both.
    • CommentAuthorEd Davies
    • CommentTimeFeb 1st 2016
    Totally irrelevant trivia: day 2 is 1900-01-01 in LibreOffice Calc (and I think with different settings in Excel) on account of how originally Microsoft messed up and replicated Lotus-123 behaviour by treating 1900 as a leap year, when it wasn't:

    • CommentTimeFeb 1st 2016
    Was that the reason, often wondered.

    Now just to work out what MS thinks 0 is, odd or even (it is even).
    • CommentAuthorbarge17
    • CommentTimeFeb 2nd 2016
    thanks for your input, I am actually using Open Office Calc for the SS when I get back to it, so far it has done everything I wanted with the Excel SS that Mike7 sent me. I'll keep you informed.

    The energy input from the wood burner will be measured in cages/week ( IBC cages) - we shall only burn what is home produced, and that is limited at the moment. The gas boilers will probably be used in the "shoulder" months because we don't have a proper thermal store (yet) and tar was becoming a problem last Spring when a full burn was too much for a day's use which left the log burner idling a lot.
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