Quick answer
No plug-in heater is more "efficient" than another. They all turn about 100% of their electricity into heat. The cheapest one to run is the one that heats only the room you're in, warms up fast and has a thermostat. A 1200W ceramic heater like the K1 costs about 16p an hour in typical use at the Ofgem cap of 26.32p per kWh.
Efficiency explained in plain English
When people search for an "energy-efficient heater", they usually mean "a heater that's cheap to run". These are not the same thing. Whether it's a fan, oil, convector, halogen or ceramic heater, almost every watt of electricity it uses ends up as heat in your room. There's nowhere else for the energy to go.
So a 2000W heater running for an hour always uses 2 kWh, and a 1200W heater always uses 1.2 kWh. What changes your bill is how much power the heater draws, how long it runs, and how much of your home you heat.
The one real exception is a heat pump, which moves heat in from outside and can give around three units of heat per unit of electricity. But a heat pump is a whole-home system costing thousands of pounds to install, not something you plug into the wall.
Heater types compared: cost per hour
Costs below are at full power, using the Ofgem price cap of 26.32p per kWh (1 October to 31 December 2026). With a thermostat, most heaters use less once the room is warm.
| Heater type | Typical power | Cost per hour | Warm-up | Best for |
|---|---|---|---|---|
| Fan heater | 2000W | 53p | Instant | Quick bursts of heat in a small room |
| Ceramic (PTC), e.g. Ofenwerk K1 | 1200W | 32p | Seconds | One room for a few hours; bedrooms, offices |
| Oil-filled radiator | 2000W | 53p | 20–30 minutes | Steady warmth in a room heated all day |
| Convector heater | 2000W | 53p | 5–10 minutes | Background heat in a larger room |
| Halogen heater | 1200W | 32p | Instant | Spot heating one person; little room warmth |
| Infrared panel | 600W | 16p | A few minutes | Wall-mounted, fixed rooms |
| Storage heater | 2500W | 66p | Charges overnight | Homes on Economy 7 off-peak tariffs |
Typical power figures are common UK models; check the wattage on any heater you buy. Storage heaters are usually charged on cheaper off-peak electricity, so their real cost depends on your tariff.
What actually lowers your heating bill
- Heat the room, not the house. Warming one room you're sitting in uses far less energy than heating every room.
- Use the thermostat. Once the room is warm, the heater cycles on and off, roughly halving its running cost.
- Match the wattage to the room. About 1000–1500W suits a room up to 20 m². Oversized heaters just use more per hour.
- Choose fast warm-up for short use. If you only use a room for an evening, a heater that's warm in seconds wastes less than one that takes 30 minutes.
- Stop draughts. Close doors, draw curtains at dusk and use draught excluders. It's free heat you keep.
- Check your tariff. On Economy 7 or other time-of-use tariffs, heating during cheaper hours costs less.
Work out your own figures with our running cost calculator.
What it costs to run (current UK prices)
At the Ofgem price cap of 26.32p per kWh (1 October to 31 December 2026), a 1200W heater like the K1 costs about 32p an hour at full power. Once the room is warm the thermostat switches the heater on and off, so in normal use it averages about 16p an hour.
| How long | Typical cost per day | Over 30 days |
|---|---|---|
| 1 hour | 16p | £4.74 |
| An evening (4 hours) | 63p | £18.95 |
| A working day (8 hours) | £1.26 | £37.90 |
Your own price may be a little higher or lower depending on your region and tariff. See how we calculate running costs or try the running cost calculator with your own unit rate.
Plug-in heater vs central heating
Gas central heating costs about 7.97p per kWh of gas, while electricity costs 26.32p per kWh. Unit for unit, gas is cheaper. A plug-in heater only saves money when it lets you turn the central heating down or off in rooms you aren't using, for example working from home in one room all day, or warming a bedroom for an hour before sleep.
If you run a heater alongside central heating that's already warming the whole house, your bill will go up. Read more in plug-in heater vs central heating.
How the K1 compares with other heaters
| Heater type | Warm in | Running cost | Safety and comfort |
|---|---|---|---|
| Ofenwerk K1 (ceramic) | About 2 seconds | About 16p/hour typical | Tip-over and overheat cut-off, cool-touch case, no glowing coil |
| Coil fan heater (2–3kW) | Seconds | 53–79p/hour at full power | Hot coil, can smell of burnt dust, often noisy |
| Oil-filled radiator (1.5–2.5kW) | 20–30 minutes | 39–66p/hour at full power | Surfaces get hot, heavy to move |
| Convector (2kW) | 10–15 minutes | About 53p/hour at full power | Heat rises to the ceiling first |
| Electric blanket (100W) | 10–20 minutes | About 3p/hour | Warms the bed only, not the room |
Full-power costs worked out at 26.32p per kWh. Thermostats lower all of these in real use.
Energy-saving myths to avoid
- "Costs just 1p an hour." Impossible for a heater that warms a room. Even 500W costs about 13p an hour.
- "Cuts your bills by 90%." No heater can promise this. Savings depend entirely on what you switch off.
- "Uses almost no electricity." Heat output equals power used. Low power means little heat.
- "Special technology beats the laws of physics." Ceramic, infrared and oil heaters all turn electricity into heat at about the same rate.
See exactly how we calculate running costs.
Buyer's checklist: an energy-smart heater
- Built-in thermostat so it isn't running flat out
- Fast warm-up so you don't pay to wait
- Sensible wattage for one room (around 1200W)
- Light and portable, so you only heat the room you're in
- Tip-over and overheat safety cut-offs
- UK 3-pin plug and a clear UK warranty
The Ofenwerk K1 ticks every box, with a 30-day money-back guarantee and 24-month warranty.
Using any electric heater safely
These tips follow UK fire-service and Electrical Safety First advice and apply to any portable heater, including ours:
- Plug the heater straight into a wall socket. Don't use an extension lead or adaptor; they can overheat.
- Keep it at least 1 metre from curtains, bedding, clothes and furniture.
- Stand it on a flat, hard, stable surface where it can't be knocked over.
- Never cover it or dry clothes on it.
- Switch it off at the wall when you go out.
- Check the plug and cable now and then. Stop using it if either is damaged or feels hot.
- Make sure you have a working smoke alarm on every floor. Many UK fire services fit them free for older residents.
When the K1 is not the right choice
We'd rather you buy the right heater than return ours. The K1 is probably not for you if:
- You want to heat a large open-plan space over about 20 m² with one heater.
- You want to replace central heating for the whole house.
- You need total silence. The K1 has a gentle fan sound.
Frequently asked questions
What is the most energy-efficient electric heater in the UK?
Every plug-in electric heater turns close to 100% of its electricity into heat, so none is truly 'more efficient' than another. The cheapest to run is the one that heats only the room you're in, warms up quickly and has a thermostat, such as a ceramic PTC heater.
Are ceramic heaters cheap to run?
They cost the same per kWh as any electric heater, but they warm up in seconds and cut back once the room is warm, so they often run for less time. The Ofenwerk K1 costs about 16p an hour in typical use and 32p at full power.
Is there a 1p per hour electric heater?
No. A heater that genuinely heats a room cannot run for 1p an hour on UK electricity prices. Even a small 500W heater costs about 13p an hour at full power at 26.32p per kWh.
Is an oil-filled radiator cheaper to run than a ceramic heater?
Not per hour of full power: a 2000W oil radiator uses more electricity than a 1200W ceramic heater. Oil radiators hold heat longer, so they suit rooms heated all day; ceramic heaters suit rooms used for a few hours.
Is a plug-in heater cheaper than central heating?
Gas costs about 7.97p per kWh against 26.32p for electricity, so a plug-in heater only saves money when it lets you turn down or switch off the central heating in rooms you aren't using.
Are heat pumps more efficient than electric heaters?
Yes. A heat pump can produce around three units of heat per unit of electricity, but it is a whole-home installation costing thousands of pounds, not a plug-in heater.
What wattage heater do I need?
As a rough guide, about 1000–1500W suits a room up to 20 m². Bigger isn't cheaper: an oversized heater simply uses more power per hour.
Do heaters with a thermostat save money?
Yes. A thermostat stops the heater running at full power once the room is warm, which typically halves the electricity it uses compared with running flat out.
Sources and how we checked this guide
- Electricity price: Ofgem: energy price cap unit rates and standing charges, checked 25 October 2026.
- Heater safety: UK fire and rescue service advice and Electrical Safety First guidance on portable heaters.
- K1 figures (1200W, about 2-second warm-up, room size up to 20 m², safety cut-offs) come from the product specification.
- Costs are worked out with the method on how we calculate running costs.
Further reading: Energy Saving Trust home energy advice.
Related: cheapest heater to run UK · ceramic heaters · K1 vs oil-filled radiator.