ASHP Energy Consumption: Aira 12kW heat pump

Wally · 2026-01-06T10:18:53Z

This is our first winter with our Aira 12kW heat pump. It was commissioned the end of September 2025. The energy consumption and associated costs are terrifying us. Our 1.5 storey home was previously heated by oil and our combined monthly energy costs, oil and electric, was circa £140 / month. In December 2025 we ran up a bill of over £300. January I reckon it’s going to be closer to £500. We have the thermostat set to 19C. The other day the upstairs of our home, which we rarely use, was 21C whereas a downstairs room which we use in the evening was 15C! We had to use blankets to keep warm! Aira don’t have a zone system and treat the entire house as one room. We are on a Good Energy Time Of Use tariff. I am becoming to realise that such a tariff is of little benefit to us unless we have a battery. The only benefit I see from such a tariff is for our own domestic devices, washing machine and dishwasher. It contributes very little to the running of our heat pump. In fairness to Aira they are working with us on this. However we were told by both Aira and Home Energy Scotland (who carried out a very detailed survey) that we would save money. We don’t see it. I read people stating that the savings will kick in over spring and summer but I fail to see that. Our energy consumption will be exactly as it was when we had oil, so where are the great savings? I am posting to this forum in the hope that more experienced ASHP users can offer us advice and/or recommendations on how we can better manage the ASHP and possibly reduce our energy bill. Thank you for reading this very lengthy posting!

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JamesPa

(@jamespa)

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08/01/2026 6:16 pm

Posted by: @chandykris

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but with a big push towards EVs it would be surprising if they are dropped completely.

I doubt that matters, ToU tariffs are for the benefit of the grid and electricity suppliers not to aid the transition to EVs. They have been around for decades as a means of load shifting (and thus balancing). With increased electrification they should, in principle, become more important still but apparently (according to @transparent) the government is being pushed by the industry for 'upgrade max' (my words) to deal with electrification rather than sensible load management.

This post was modified 18 hours ago by JamesPa

4kW peak of solar PV since 2011; EV and a 1930s house which has been partially renovated to improve its efficiency. 7kW Vaillant heat pump.

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Transparent

(@transparent)

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09/01/2026 11:03 am

Posted by: @jamespa

↑

more important still but apparently (according to @transparent) the government is being pushed by the industry for 'upgrade max' (my words) to deal with electrification rather than sensible load management.

Indeed.

Present ToU tariffs are based on national supply and demand statistics.

But most of the new renewable sources of generation are connected at the EHV (33kV and 132kV) levels of the grid.
The electricity passes down from there to reach consumers across the 11kV level.
It doesn't go upwards to the 400kV National Transmission Grid.