Why this comparison is sensitive
Gas can be cheaper per unit than electricity, so an efficient heat pump must make up the difference through seasonal performance. A strong SCOP, suitable radiators, good controls, and fair tariffs can improve the case.
A weak design or high electricity tariff can make annual savings small or negative. Use your own supplier rates rather than a national average.
Example calculation
If a home needs 12,000 kWh of useful heat, an 88% efficient gas boiler uses about 13,636 kWh of gas. A heat pump at SCOP 3.2 uses about 3,750 kWh of electricity.
Multiply both figures by your current rates to compare. Then include installation cost, grants, maintenance, and comfort goals before deciding.