What drives running cost
SCOP (Seasonal Coefficient of Performance): UK average 2.94 in EST 2024 trial. Higher SCOP = lower running cost. Modern Cambridge new-builds hit SCOP 3.4–3.8.
Building heat loss: solid-wall pre-1919 home needs ~30–50% more energy than a comparable cavity-walled semi.
Electricity tariff: heat-pump-friendly tariffs (Octopus Cosy, EDF Heat Pump) are 30–40% cheaper than standard variable for off-peak hours.
Heating control sophistication: weather compensation + smart scheduling can reduce running cost 5–15%.
Hot water demand: 200-litre cylinder for 4 people draws 2,500–3,500 kWh/year on top of space heating.
By property type (3-bed equivalent on Cosy tariff)
Detached 4-bed solid-wall: £1,300–£1,800/year.
Detached 4-bed cavity-wall well-insulated: £900–£1,200/year.
Semi-detached 3-bed: £900–£1,200/year (UK median).
Terraced 2–3 bed: £700–£1,000/year.
Flat (1–2 bed): £500–£800/year.
Bungalow 3-bed: £900–£1,200/year.
Heat-pump-friendly tariffs (worth switching to)
Octopus Cosy: cheap windows 04:00–07:00 and 13:00–16:00 — excellent for heat pumps that pre-heat thermal mass.
EDF Heat Pump tariff: alternative time-of-use structure with similar economics.
OVO Heat Pump Plus: relatively new, comparable to Cosy.
Good Energy Heat Pump rate: green-energy-focused.
Switching from a standard variable tariff typically saves £200–£400/year.
FAQ
Is electricity expensive enough to make heat pumps not worth it?
On the 2026 Ofgem price cap, a heat-pump-friendly tariff makes heat pumps cheaper to run than a gas boiler for typical UK homes. The economics depend on SCOP and tariff — SCOP 3.0+ on a heat-pump tariff is the breakeven threshold vs mains gas.
Will my electricity bill triple?
It will increase, but not as much as people fear. A typical UK home consumes 2,900 kWh/year of electricity for non-heating use; adding a heat pump adds 4,000–5,000 kWh of new electricity demand. Total goes from £900 to £1,800 (Cosy tariff) — but you offset £1,200+ of gas bill, netting a saving.
Do I need solar panels for it to make sense?
No. Solar PV pairing improves payback further but isn't required. Heat pumps make economic sense on grid electricity alone given the 2026 price cap.
What's the cheapest hour to run my heat pump?
On Octopus Cosy: 04:00–07:00 (lowest-rate window). The heat pump can heat your hot-water cylinder and lift home temperature during this window, then coast through the day. Smart heat-pump controls automate this.
Sources
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