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Retrofitting our 1999 house from a C2 to an A1

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  • 20-08-2023 11:18pm
    #1
    podge3
    Registered Users Posts: 1,742 ✭✭✭


    I’ve been interested for quite a while in getting home energy retrofitting works carried out on our house. I finally started getting quotes early last year – just before the increased SEAI grants - and got caught up in the One Stop Shop fiasco so its really only now that the works are almost finished.

    Just for context, our house is a detached dwelling, about 190 sq metres and built in 1999. It is block built, not timber framed. The only real changes I’d made from an energy upgrade point of view over the years was most of the windows were changed to triple glazing about 10 years ago and a new composite front door about 2 years ago.

    The house was heated with oil and we were burning about 2,500 litres per year. The boiler was the same age as the house so really needed to be replaced. It was probably about 85% efficient when new, maybe 70 odd % after over 20 years. From the quantity of oil used (@ 75% efficiency), we were producing about 18,750 kwh of energy for heat purposes.

    I was really interested in getting a heatpump but wasn’t really sure it would be suitable in our house as we didn’t have underfloor heating. I got some great non-partial advice here on Boards (and elsewhere) before I made enquiries from retrofitting companies.

    My initial shopping list was as follows:

    ·      Heat pump

    ·      Attic insulation

    ·      Cavity walls pumped

    I got several prices for the above, which varied from €11.5k to over €30k.

    I subsequently added solar PV and a composite back door, solar was €12.5k and the composite door was about €1.5k.

    All prices are after whatever grants are available.

    The initial BER rated the house at C2, with 195 kwh/m sq/year. The HLI was 2.35.

    The heatpump was installed first, just before the really cold spell in December so it was a good test. The company was mad busy so it was April of this year before the attic and walls were insulated. I would expect the electricity consumption figures below will be better this winter.

    The heatpump is an 11.2 kw unit and all the rads were changed for larger panels. The kwh consumption/generation figures since last December are as follow:

    image.png


    I am very happy with the performance of the HP so far. Even the coldest days in December where it never got above 0 degrees, I was still getting a COP of 2 and the house was warm. In general., both my wife and I agree that the house was never as warm with the oil as it is with the HP.

    I’m getting an average COP of about 3 but I haven’t played around yet with weather compensation etc. Now that I’m somewhat used to the system, I’ll try a few things next winter.

    You will notice the COP in the summer months is worse than winter. This is because the HP is just doing DHW now and that results in a lower COP.

    At a rough guess, over a full 12 months, I expect the HP to use about 6,500 kwh and generate about 18,500 kwh of heat. This is remarkable close to the guestimation of heat generated from the oil. I was on the brilliant Energia EV rate since before last winter (thanks again to Boards) so our heating costs for the year will be about €1,300, about half that oil would have cost. Even with less favourable electricity rates,  the HP would still have been cheaper to run.

    I have already mentioned my solar system in the quotes thread here on Boards. Its working great and we will be off grid for the summer months. It will also help a little with the HP consumption during the winter.

    In conclusion, our house went from a at C2, 195 kwh/m sq/year,  HLI of 2.35 to an A1, -2 kwh/m sq/year, HLI of 1.9. We are a net contributor! Not really sure I believe all the BER stuff TBH, no way our house is as good as a new build with loads of insulation.

    So that’s it. We are delighted with the works we had done, total cost was about €25k. 

    Post edited by podge3 on


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