Can an Air Conditioner Heat Your Home?
Yes — modern inverter air conditioners can heat a room far more efficiently than a classic electric heater. Instead of converting electricity directly into heat (efficiency = 1), they move heat from the outdoor air inside, achieving a Coefficient of Performance (COP) of 2.5 to 5.
COP Explained: What It Means in Practice
A COP of 3 means: for every 1 kWh of electricity consumed, the unit delivers 3 kWh of heat. An electric radiator always delivers exactly 1 kWh of heat per 1 kWh of electricity — so the air conditioner is 3× cheaper to run.
| Heating method | COP / Efficiency | Cost per kWh of heat (at €0.25/kWh) |
|---|---|---|
| Inverter AC (heat pump) | 3.0 | €0.083 |
| Electric radiator | 1.0 | €0.250 |
| Gas boiler | 0.95 | ~€0.120 (at €0.11/kWh gas) |
When Does AC Heating Pay Off?
If you already own a portable air conditioner, activating heat mode costs nothing extra. The running costs are dramatically lower than electric heating. For homes without central heating (apartments, home offices, conservatories), AC heating is the most cost-effective electric option.
Limitations in Very Cold Weather
Most portable ACs maintain good COP down to 0 °C outside. Below −5 °C, efficiency drops. For the mild winters of Western and Southern Europe, this is rarely a concern.
Is AC heating better than an electric radiator?
Yes — an inverter AC on heat mode uses 2–4× less electricity than an equivalent electric radiator to deliver the same warmth. Over a winter, this can save €100–300 on electricity bills.
Does an air conditioner use more electricity heating or cooling?
Heating mode typically has a higher COP than cooling mode, so it is often more efficient in mild outdoor temperatures. Power consumption is similar (800–1500 W for portable units).