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Thread: Evohome savings

  1. #1
    Automated Home Jr Member
    Join Date
    Jan 2009

    Default Evohome savings

    Entering meter readings today and got the summarised gas savings since installing Evohome in December:-

    Winter (Dec - Mar) 5991 units vs 6343 last year (66.5 units/ day vs 70.5 last year). Slight improvement but bad time to compare as was "tuning" Evohome and cleaning system, etc quite a lot with higher than normal use.

    Spring (Apr - Jun) 3972 units vs 5077 last year (43 units/ day vs 55 last year). Around 20% down... more in line with expectations.

    Summer remains unchanged at around 1400 units. I used to put heating off all day and just run water for a coupe of hours so didn't expect much difference. I think there is scope to improve Evohome savings during summer but the scheduling is a bit cumbersome for season changes- need to look at more IFTTT macros or other intelligence to sense occupancy/ water use more!

    This gives tangible actual energy saving for spring 2015 of around 50. Extrapolating this looks to give savings of 100 - 150 a year (Total gas/ elec bill is only 125/ month so not high use).
    Comfort wise, I was working from home for a significant amount of the period and had study only heated (and more comfortable) vs having heating completely off for much of the day.

  2. #2
    Automated Home Legend
    Join Date
    May 2014


    Having posted before on this subject, I do so again with a degree of trepidation. My Evohome system has now been installed for over 13 months so I have a year's actual consumption to look back on. Prior to the installation of Evohome, I had an AQ (Annual Quantity - as recorded by the gas industry data collectors) for my home of 10400kWhs. For the period, 15 August 14 to 13 August 15, my gas consumption has fallen to 8716kWhs (assuming an average calorific value of 39.2) which equates to an annual saving on gas usage of 16.19%.

    Sadly, kWhs saved is only part of the calculation. Looking at my current gas tariff, the annual cost for 10400kWhs would be 373 compared to a cost of 324 for 8716kWhs. It follows that my ACTUAL annual saving is just under 50 or 13.14% per annum.

    On a more positive note, zoning systems do have one unique selling point which is that heat is available where the homeowner wants it to be which as one gets older is increasingly important. In this respect, we have had heating on at times of the day when in the past it would most likely have been off.

    System Details:

    Five bed modern detached house with gas-fired conventional boiler; unvented OSO HW system and 21 radiators. Evohome comprises smart controller; 2 BDRs; HW kit and 21 HR92s.

  3. #3
    Automated Home Jr Member
    Join Date
    Feb 2015


    We've had our Evohome system installed since late December 2014, so don't have a full year's data to compare yet. I do have meter readings going back several years however and when the system was installed we had used 11223 KWhrs in the previous 12 months to that date. In the 12 months to this week this has dropped to 9845 KWhrs, a reduction of 12.2%. I expect that this rolling annual usage will drop further until the Evohome has been in use for an entire year. One other thing to note is we took a holiday in May 2014 but didn't this year and the heating was on quite a bit this May. So it's possible that the saving could have been greater had we repeated last year's holiday calendar.

    Using this year's energy supplier's costs, we would have spent 459 in the period 27/12/2013 to 26/12/2014. This year between 11/8/2014 ~ 10/8/2015, that same energy would have cost 412 so we're saving 47 per year. As mentioned above, this figure will likely go down once the system has been in use for a full year and once holidays have equalised themselves.

    I'd repeat HenGus' observation though - the heating is now on more often because we can. Heating the entire apartment just because one room was cold would likely not be done. Now it's possible, so we're more comfortable with each room at the required temperature.

    System Details:
    Three bedroom apartment in a converted period building. Condensing combination gas boiler and 10 radiators.

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