Room by room
Conservatory heating that stands a chance
The short answer
A conservatory is mostly glass, and glass is a poor insulator. Any honest guide has to start by admitting that no plug-in heater will make a large, single-glazed conservatory warm on a freezing January night.
Written and checked by the RapidHeat UK team · Last updated September 2026 · how we work out running costs
Key takeaways
- Glass loses heat fast, so expect to need more power than the floor area suggests.
- Warm the space 20–30 minutes before you use it rather than trying to hold it warm all day.
- Thermal blinds or curtains cut heat loss more cheaply than any heater upgrade.
Why conservatories are so hard to heat
Heat escapes through glazing several times faster than through an insulated wall. A room with glass on three sides and a polycarbonate roof can lose its warmth within minutes of the heating going off. Anything you do to slow that loss increases what a heater can achieve.
Do these before you buy a heater
- Fit blinds — thermal or honeycomb blinds cut roof and window losses noticeably.
- Seal draughts around doors, frames and the base of the structure.
- Close the door to the house, so you are not dragging warm air out of the lounge.
- Lay a rug on a tiled floor; cold floors make a room feel several degrees colder.
- If the roof is polycarbonate, an insulated roof upgrade changes the room completely.
Expected heater sizing
| Conservatory | Realistic goal | Power needed |
|---|---|---|
| Small, double glazed, blinds fitted, up to 8 m² | Comfortable for an evening | 1,200–1,500 W |
| Medium, 10–14 m², insulated roof | Comfortable with the door to the house open | 1,500–2,000 W |
| Large or single glazed, glass roof | Take the edge off while you are in the room | 2,000 W plus, or fixed heating |
Which type of heater
Fast-response heating suits a room you use in bursts. A ceramic fan heater reaches temperature in minutes, which is what you want for two hours on a Sunday afternoon. An oil-filled radiator takes 20 to 30 minutes to get going and then loses that heat to the glass — the wrong tool here. Full comparison in ceramic vs oil-filled.
What it costs
At 27p per kWh, 1,500 W flat out is about 41p an hour. In a leaky conservatory the thermostat will rarely cut out, so budget close to the full-power figure — perhaps £1.20 for a three-hour afternoon. That is still far cheaper than heating the whole house to make one glass room usable. Method in electric heater running costs.
Where RapidHeat fits
RapidHeat is well suited to a small or medium conservatory with blinds and double glazing, used in sessions rather than all day: switch it on, get warmth within about five minutes, use the room, and let the timer switch it off. In a large single-glazed conservatory it will make the space more pleasant without making it cosy — we would rather say that plainly than sell you a heater that disappoints.
RapidHeat ceramic heater
4.8/5 · 1,247 UK customers£49.95· £89.91 for two · £110.89 for three (about £36.96 each)
- Thermostat, timer and remote
- Warm room in about 5 minutes
- Free tracked UK delivery
- 30-day money-back guarantee
Perfect for my cold office
I have a small office with a door that gets really cold because the building management keeps the winter temperature far too low for comfort. I plugged this into the socket above my desk and now I am warm without anyone even knowing it is there. I love it.
Great in the bathroom
We use it to take the chill off the bathroom before the kids' bath time. Warms up fast and the timer is handy. Four stars only because I wish the display were a little dimmer at night.
Worth being straight about: RapidHeat is built for rooms up to about 12 m². It is not a replacement for central heating and it will not transform an open-plan lounge or an uninsulated garage. If it is not right for your room, send it back within 30 days.
Questions people ask
- What size heater do I need for a conservatory?
- Allow noticeably more than the usual 100 W per square metre — often 150 W or more per m² for single-glazed or older conservatories. For a small conservatory, 1,500 W or two heaters is realistic.
- Why is my conservatory so cold?
- Because glass and a polycarbonate roof lose heat many times faster than an insulated wall. Any heater is fighting that loss continuously, which is why blinds and draught-proofing pay for themselves.
- Is it expensive to heat a conservatory?
- It costs more than an equivalent-sized room indoors. A 1,500 W heater is about 40p an hour at 27p per kWh, and in a cold conservatory the thermostat will keep the element on for much of that hour.
- Should I leave a conservatory heater on low all winter?
- Only if you need frost protection for plants. For general use it is cheaper to heat it on demand for the hours you are actually in there.
Get more use out of your conservatory
Order RapidHeat today with free tracked UK delivery and a 30-day money-back guarantee.
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