What does it cost to heat a greenhouse?
Pick one of our greenhouses or enter the glazed surface yourself, choose how warm it should stay and see the electric heating cost from October to April, plus the heater size you need.
Estimated heating cost, October to April
£214
813 kWh with an electric heater.
Heater size for a cold night (−6 °C outside): at least 1500 W.
Cost per month
- Oct£0
- Nov£18
- Dec£48
- Jan£51
- Feb£47
- Mar£35
- Apr£14
How we calculate
A greenhouse loses heat through every pane. How fast depends on the glazing: single glass lets through about 5.8 watts per square metre for each degree of difference, 4 mm twin-wall polycarbonate about 3.9, 10 mm about 3.0. Bubble wrap on the inside brings glass down to about 3.4.
For each month we take the Met Office average night-time low for the UK (1.5 °C in January) and count 14 hours of heating a night whenever that low sits under your target. Days are warm enough from the sun alone. The glazed surface counts the walls, both gable ends and the roof; a lean-to has no back wall. When a maker does not publish the eave height, we use two thirds of the ridge height.
The default price is the Ofgem cap for October to December 2026, 26.32p per kWh. The heater size covers a hard frost of −6 °C. Average figures hide cold snaps and mild spells, a frosty pocket in the north costs more than a sheltered garden in Cornwall. Treat the result as an estimate.
Still choosing a greenhouse? Try the greenhouse finder or read how we score.