Before you begin
What affects heat-pump running costs
Use annual fuel consumption or a BER advisory report to choose heat demand where possible.
Do not use a product laboratory COP as the expected seasonal COP.
For a smart tariff, take the rates and the hours from the tariff’s own price list rather than from a headline night rate. What decides the blend is how much of the heating actually lands in the cheap window, which a scheduled heat pump can control and an on-demand one largely cannot.
Reading the answer
Understanding your heating-cost comparison
A cheaper result is only protected if the installed system actually achieves the assumed SCOP.
Running cost excludes the capital cost, grants, finance and maintenance.
Boundaries
Assumptions and limitations
Working assumptions
- Kerosene contains 10.35 kWh per litre.
- The gas and kerosene fields open on published national figures and are yours to overwrite. Both are volumetric prices including VAT, so they are the same kind of number as the electricity rate and the three fuels can be compared directly.
- Heat-pump useful-heat cost equals electricity rate divided by SCOP.
- Smart-tariff running cost uses the blended rate you enter, not a maintained tariff.
- Standing charges are excluded across fuels.
Where to be careful
- Emitter sizing, flow temperature, weather compensation and commissioning strongly affect real performance.
- A poorly insulated house may need insulation and draught-proofing work before a heat pump is suitable.
Worked example
The same question, answered end to end
A house needing 14,000 kWh of heat a year, currently on kerosene at €1.28 a litre through an 80%-efficient boiler, considering a heat pump at SCOP 3.7 on a 36c unit rate.
What was entered
- 14,000 kWh of useful heat a year — heat delivered to the rooms and hot water, not fuel bought.
- Kerosene at €1.28 a litre, through a boiler running at 80% over the year.
- Electricity at 36c per kWh, and a designed SCOP of 3.7.
- Reasonable but not excellent insulation.
How it is worked out
A litre of kerosene holds 10.35 kWh, so €1.28 buys 10.35 kWh of fuel — about 12.4c per kWh of fuel.
At 80% boiler efficiency only 8.28 kWh of that reaches the rooms, so useful heat costs about 15.5c per kWh.
14,000 kWh of useful heat at 15.5c is about €2,164 a year on oil.
A heat pump at SCOP 3.7 delivers 3.7 kWh of heat per kWh of electricity, so 36c buys 3.7 kWh — about 9.7c per useful kWh.
14,000 kWh at 9.7c is about €1,362, and the difference is the annual saving.
What the tool returns
- Current heating
- €2,164/year
- Heat pump
- €1,362/year
- Annual difference
- €802 saved
- Heat-pump cost per useful kWh
- 9.7c/kWh
Common questions
Questions about this tool
What is SCOP?
SCOP is seasonal heat delivered divided by electricity used. A SCOP of 3.5 means roughly 3.5 kWh of heat per kWh of electricity over the season.
Can a heat pump be dearer than gas?
Yes. With a low SCOP and an expensive electricity tariff it can match or exceed efficient mains-gas heating.