Advanced options
What The Storage Heater Cost Calculator Works Out
- Per night's charge: heater rating in kW x charge hours gives the kilowatt-hours stored in the brick core, multiplied by the Economy 7 night rate. A 2kW heater charging for seven hours stores 14 kWh, about GBP 1.82 at 13p.
- Per month: the nightly charge x 30, assuming a full charge every night. Autumn and spring want half-charges, which the input dial exists to provide.
- Same heat at the day rate: what those units would cost at a single-rate or daytime price (defaults to the current Ofgem price cap unit rate). The near-half saving is the entire technology, and the corollary every mis-billed flat discovers is that storage heating on a single-rate tariff is simply expensive electric heating with extra steps.
- Day rate (advanced): Economy 7 day rates are usually a few pence above the single-rate price, so enter your own to see the true gap. The trade only pays when heating and hot water genuinely shift to the night window.
- Number of heaters (advanced): multiplies the stored heat for a whole flat. Enter the average rating if they differ.
- Heating months per year (advanced): turns the monthly figure into a season. Six months (October to March) is typical; a well-insulated flat may need four.
- Daytime boost (advanced): hours a day the built-in convector runs at the day rate, and its rating. This is the classic budget leak: an hour of 1kW boost every evening adds about GBP 8 a month at the current price cap unit rate.
- Heat pump for the same heat (advanced): an air-to-air heat pump delivering the same kilowatt-hours of heat at the day rate, divided by its coefficient of performance (COP). At COP 3 it beats even night-rate resistance heat, which is worth knowing before replacing a fleet of heaters.
- Night-rate saving per season (advanced): the monthly day-rate saving multiplied by the heating months. Modern high-heat-retention (HHR) heaters, insulated and fan-released, hold the charge into the evening the old bricks lost by teatime. Note that the meter's night window follows the meter's clock, not BST.
Tariff guidance: Ofgem.