How Much Does It Cost to Heat a Garden Dome?
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Quick answer
For illustration, at an assumed 25p per kWh, a 2 kW electric heater costs 50p an hour at full power, so a three-hour evening in a garden dome costs £1.50 at most, and less once the thermostat is cycling. That's usually less than people fear. The real cost depends on the dome's size, the base, your heater and, above all, how you use it: heating only for the hours you're in it keeps costs modest.
What actually drives the cost
Rather than quote one number that won't match your situation, here's what moves it:
- Size. A smaller dome has less air to heat, so it costs less to warm and gets comfortable sooner. Bigger domes ask for more: floor space runs from 5.7 m² in the Mini to 9.6 m² in the Standard and 19.6 m² in the Large.
- Specification. This one is about strength, not warmth. Ultra panels are 30% thicker than Original and Extreme panels twice as thick, to cope with wind and exposure rather than to keep heat in. Choose the specification for your site, not your heating bill.
- How well the base is sealed and insulated. Heat is lost through gaps and a cold floor as much as anything. A well-fitted, insulated base makes a real difference to running cost; our guide on how to insulate a garden dome covers the options.
- Your heater. A modern thermostatic electric heater that holds a set temperature uses far less than one left blasting at full power. Match the heater to the space.
- Usage: the big one. Heating a dome on demand, for the hours you're actually in it, costs a fraction of trying to keep it warm around the clock. Heat it like a room you pop into, not like a house.
Whatever you choose, keep it safe. Electric heat is the simplest option, with no flue and no fumes. Any fuel-burning heater needs ventilation and a carbon monoxide alarm, a wood burner needs a HETAS-registered installer, a proper flue and the clearances the installer specifies, and every heat source belongs well away from the panels. Our guide to heating a garden dome compares the options.
What it costs in practice: illustrative examples
Energy prices change, so treat these as worked examples rather than quotes. They assume an illustrative 25p per kWh; swap in the unit rate from your own bill. The sum is simple: the heater's power in kilowatts, times the hours it runs, times your unit rate.
| Illustrative example | Energy used | Cost at 25p per kWh |
|---|---|---|
| 2 kW electric heater, 1 hour at full power | 2 kWh | 50p |
| 2 kW heater, a 3-hour evening at full power | 6 kWh | £1.50 |
| The same evening, thermostat cycling the heater about half the time | 3 kWh | 75p |
| 2 kW heater left on day and night, cycling about half the time | 24 kWh | £6 a day |
How hard the thermostat works depends on the weather, the size of the dome and how well the base is insulated, so your own figures could be higher or lower. The pattern is what matters: an evening heated on demand costs well under a couple of pounds in these examples, while keeping the dome warm around the clock multiplies the bill.
Why a dome costs less to heat than you'd expect
Two things work in your favour. First, it's a contained space: there's only so much air, and a small space warms through fast, so you're not paying to heat it for long before it's comfortable. Second, you decide when to heat it: unlike a house, a dome doesn't need keeping warm while nobody's in it, so you only pay for the hours you use.
The honest flip side: solid polycarbonate isn't an insulator, so warmth passes out through the panels much as it does through single glazing, and the dome cools fairly quickly once the heater goes off. That's exactly why heating on demand suits a dome, and why the base, draughts and soft furnishings matter more than the panels. Add a sensible heater used on demand, and the cost of an evening in the dome is genuinely modest.
Simple ways to keep running costs down
- Heat on demand. Warm it up shortly before use rather than keeping it heated all day.
- Choose a thermostatic heater. It holds the temperature instead of overshooting.
- Insulate the base. Stop heat escaping downward: one of the cheapest wins.
- Add soft furnishings. Rugs, throws and cushions hold warmth and make the space feel cosier sooner.
- Use the included roof vents wisely. With an electric heater, keep them closed while you're heating and open them when you need to clear moisture: balance warmth and airflow (our ventilation guide explains how).
- Cut draughts and line the lower panels. Keep the door shut while heating, and on the coldest evenings hang thermal curtains or blankets along the lower panels, well clear of the heater.
Frequently asked questions
Is a garden dome expensive to heat?
Generally not. It's a small, contained space that warms quickly, and heating it only when you're in it keeps costs modest. For illustration, at 25p per kWh a 2 kW electric heater costs 50p an hour at full power, and less once its thermostat is cycling.
What's the cheapest way to heat a dome?
A thermostatic electric heater used on demand, with an insulated base and soft furnishings to hold the warmth. Heating only when you're in the dome is the biggest saving.
Do thicker panels reduce heating costs?
Not enough to choose a specification for it. Ultra and Extreme panels are thicker for strength and weather margin, but solid polycarbonate isn't an insulator at any thickness. The base, draught control, a thermostatic heater and heating on demand make far more difference to your bills.
Can I use a dome in winter without huge bills?
Yes. Heat it for the hours you use it rather than constantly, insulate the base and use a thermostatic heater, and a winter evening in the dome costs far less than most people assume.
Does the size affect heating cost a lot?
Yes. A smaller dome has less air to heat, so it costs less to run: the Mini has 5.7 m² of floor area, the Standard 9.6 m² and the Large 19.6 m².