The Nottingham Energy Partnership has a very interesting table of energy costs. Its estimates are based on a medium-sized domestic property with an annual consumption of 16.5MWh. The fourth column is p/kWh delivered and includes the standing charge for gas and electricity. They conclude that an ASHP is more expensive than gas but a GSHP is cheaper.
They assume an air source SCOP of 2.7 and a ground source SCOP of 3.5, alongside a relatively high gas boiler efficiency of 90%. The unit price differentials seem higher as well 38.4p/kWh for electric vs 11p/kWh for gas…
It’s all in the assumptions, you get different conclusions if you achieve a higher SCOP from the ASHP as many are getting here…
This is an interesting report on actual boiler efficiencies https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/180950/In-situ_monitoring_of_condensing_boilers_final_report.pdf
I think we have been using a electric unit rate of 34p/kWh vs 10p/kWh for gas here, I notice they are including standing charges as part of the unit rate which may not make sense as a gas user will still be paying the electric standing charge for standard electric consumption, whilst an ASHP user without gas cooking could do away with the gas standing charge all together…
1 Like
That report was very interesting. Particularly where it said only half the heat supplied for DHW ever reached the taps! I think it might save a lot of energy and money, if wash hand basins and sinks had hot water heated locally and only on demand. This could be like an electric shower. I have emailed the NEP to find out where they got their data. You are quite right about the assumptions.
My house has a background consumption of 300 watts. This is due to many Internet of Things gadgets, my fridge and freezer and the central heating pump. This alone is costing me £70 a month.
What is the overhead for all the gadgetry and controls for your Heat pump system?
Yes, I am wondering about heating the thermal store to a lower temp to maximise the boiler efficiency and then fit an in-line heater to boost the DHW.
I stayed in a rental cottage. Each hot water tap was fed by a small, local and well-insulated immersion heater.
I think this might save money.