Energy & bills · Updated October 2026
Energy-Efficient Heaters UK: Plug-In Heater vs Central Heating
'Energy efficient' is everywhere in heater adverts. Here's what it actually means, and how to really cut the cost of staying warm.
Quick answer
All plug-in electric heaters are about equally efficient: nearly 100% of the electricity becomes heat. Gas central heating is usually cheaper per unit of heat, but a plug-in heater can save money when it lets you heat just one room. The real savings come from heating less space, for less time.
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In this guide
All electric heaters are similarly efficient
Ceramic, oil-filled, fan, convector, halogen: every electric resistance heater turns almost all of the electricity it uses into heat in your room. A 1.5 kW heater gives off about 1.5 kW of heat, whatever the type. So "99% efficient" is true, but it's true of all of them.
Efficiency vs running cost
Efficiency tells you how much heat you get per kWh. Running cost depends on the price of that kWh. Electricity costs several times more per kWh than gas, so a 100% efficient electric heater can still cost more per unit of heat than a gas boiler that's around 90% efficient.
| Heat source | Efficiency | Relative cost per unit of heat |
|---|---|---|
| Gas boiler (central heating) | About 85–95% | Lowest |
| Heat pump | About 250–400% | Low (high install cost) |
| Plug-in electric heater | About 100% | Higher per unit of heat |
Plug-in heater vs central heating
Central heating heats every room with a radiator. If you're the only person home and you only use one room, you're paying to heat empty rooms. A plug-in heater heats only the room you're in.
| Central heating | Plug-in heater | |
|---|---|---|
| Cost per unit of heat | Usually lower (gas) | Higher (electricity) |
| Heats | Whole home | One room |
| Best for | Families, whole-house comfort | One person, one room, short periods |
| Installation | Boiler, pipes, radiators | None – plug in |
Heat only the room you're in, with a thermostat and timer.
See RapidHeat price →What about heat pumps?
Air-source heat pumps move heat from outside air into your home and can deliver around 2.5–4 units of heat per unit of electricity. They're the most efficient electric option for whole-home heating, but they cost thousands to install (grants may be available). They don't compete with a £50 plug-in heater. They solve a different problem.
Where real savings come from
- Zoning: heat only the rooms you use.
- Thermostats: stop heating once you're warm.
- Timers: never heat an empty room.
- Lower set temperature: each degree lower saves energy.
- Draught-proofing and curtains: keep the heat in.
A simple zoning plan
- 1
Turn down central heating
Lower the thermostat or radiator valves in rooms you don't use during the day.
- 2
Heat your main room
Use a plug-in heater in the room you're in, with the door closed.
- 3
Set a timer
Warm the bedroom 30 minutes before bed, then switch off.
- 4
Check your bill
Compare a couple of weeks to see what works for your home.
Marketing claims to ignore
- "1p per hour": not possible for real room heating. See running costs.
- "Cuts bills by 80%": only if you stop heating most of your home.
- "Uses less electricity than other heaters": same power means the same electricity.
Where RapidHeat fits
The RapidHeat Heater is a standard-efficiency electric heater, like all its rivals. Its value is in control: thermostat, timer, remote and low/high settings make it easy to heat one small room without waste. See the full RapidHeat guide or compare small space heater types.
Frequently asked questions
What is the most energy-efficient electric heater?
All electric resistance heaters, whether ceramic, oil-filled, fan or convector, turn nearly 100% of their electricity into heat. Heat pumps are the exception: they can deliver several units of heat per unit of electricity, but they're a fixed installation, not a plug-in heater.
Are plug-in heaters energy efficient?
Yes in the technical sense: almost all the electricity becomes heat. Whether they're cheap depends on how you use them. Heat a small room, for short periods, with a thermostat and timer.
Is it cheaper to use a plug-in heater or central heating?
Gas central heating is usually cheaper per unit of heat. A plug-in heater can be cheaper overall if it lets you heat one room instead of the whole home.
What does '100% efficient' mean on a heater?
It means nearly all the electricity used becomes heat in the room. It's true of every electric resistance heater, so it doesn't make one model cheaper to run than another of the same power.
Do energy-saving heaters really save money?
A heater can't make electricity cheaper. Savings come from heating less space, for less time, at a lower temperature: thermostats, timers and zoning.
Are heat pumps better than electric heaters?
For heating a whole home, heat pumps are much more efficient than plug-in heaters, but they cost thousands to install. Plug-in heaters are for topping up or heating single rooms.
Is it cheaper to heat one room or the whole house?
Heating one room is almost always cheaper than heating a whole house, which is why zoning (heating only where you are) is the biggest saving available.
What temperature should I set a room heater to?
Around 18–21°C is comfortable for most people. Each degree lower saves energy. Older people and those with health conditions may need it warmer.
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How we researched this guide
We read the official seller's product page, delivery and returns information, and guidance from UK bodies such as Ofgem, the Energy Saving Trust and Electrical Safety First. We have not lab-tested the RapidHeat Heater, and we don't publish customer reviews we can't verify. Anything the seller claims is labelled as their claim. Last reviewed: October 2026.