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Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
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    • CommentAuthorMikel
    • CommentTimeMar 28th 2014
     
    Our daily electricity usage this winter:

    Nov 18.6 kWh
    Dec 23.2 kWh
    Jan 23.5 kWh
    Feb 16.4 kWh
    Mar 13.4 kWh

    Our GSHP daily electricity usage

    Jan 10.6 kWh
    Feb 10.1 kWh
    Mar 8.7 kWh

    Our PV daily generation data

    Nov 4.1 kWh
    Dec 2.2 kWh
    Jan 2.9 kWh
    Feb 6.7 kWh
    Mar 9.4 kWh

    We had on average 4-5 days away in each of Jan, Feb ad Mar so those figures would need increasing by about 20%.
    I've not added any solar thermal data but since the middle of February we have not had to use the heat pump or immersion heater much at all.

    Worth quoting these figures per sq. m? or per capital invested?
    •  
      CommentAuthorSteamyTea
    • CommentTimeMar 28th 2014 edited
     
    Posted By: MikelWorth quoting these figures per sq. m? or per capital invested?
    Tricky one that, should really be against all measures. But I have a total liveable area of 56 m^2, so my usage (for the last 5 weeks) is 0.32 kWh/(m^2.day) of which 0.24 is heating and water.

    Your Heatpump seems to use a lot of electricity.
    • CommentAuthorMikel
    • CommentTimeMar 28th 2014
     
    Our area is 145 sq. m so our daily usage per sq. m for Feb/Mar works out as:

    Feb: total 0.11 kWh per sq m, heating and hot water 0.07 kWh per sq m
    Mar: total 0.09 kWh per sq.m, heating and hot water 0.06 kWh per sq.m

    First year's annual electricity consumption 4629 kWh with the heat pump
    Previous year's electricity consumption 2553 kWh
    So the heat pump seems to have added about 2000 kWh to the electricity consumption and that has replaced, together with the solar thermal, around 1300-1500 litres of heating. Estimated annual saving of around £400-500.

    Our initial results for the measured COP for the heat pump is coming in around 3.2 with hopes that this cane be increased to 3.3-3.4

    "Your Heatpump seems to use a lot of electricity."

    And there I was feeling rather pleased with all this!
    •  
      CommentAuthorSteamyTea
    • CommentTimeMar 28th 2014
     
    At a CoP of 3.2 your m^2 heating load (the actual heat needed) is just a little higher than mine, but that could be DHW usage making the difference. But you have more walls.
    • CommentAuthorMikel
    • CommentTimeMar 28th 2014
     
    It does look like the DHW has a measured effect on the CoP and we should be adding in the use of the immersion heater. Unfortunately that is not on a separate meter, so any figure will be an estimate. We haven't used the immersion heater since the middle of Feb and started to use it around the latter part of October, so about 16 times.
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