The first summer electricity bill after switching on an air conditioner often looks alarming. Costs rise and you wonder how much that cool room is actually costing. The truth is that a split unit does draw power, but significantly less than most people expect, and above all the running cost is something you can control with straightforward choices. Here are real numbers and the places where waste actually hides.
How much a unit actually uses per hour
An average single-room monosplit unit draws between 800 and 1,000 watts at full load. But it rarely runs at full load: once the set temperature is reached, a modern inverter unit modulates down to 300 or 400 watts to maintain it. In one hour of real-world use you typically consume around 0.5 to 0.7 kWh. At a European electricity price of roughly 0.25 to 0.30 euros per kWh, that is about 15 to 20 cents an hour. Eight hours of operation costs around one and a half euros.
What actually drives the bill up
- Setting too low a temperature. Each degree lower increases consumption by around 5 to 7 percent. Going from 26 to 22 degrees can inflate spending by a quarter.
- Dirty filters. Clogged filters make the unit work harder for the same cooling output.
- Old equipment. A unit with a low energy rating can consume twice as much as a current A+++ model for the same result.
- A poorly insulated space. Open shutters in direct sun, open doors and draughty windows cancel out half the unit's work.
The habits that reduce the bill
The most effective is the set temperature: at 25 to 26 degrees you feel comfortable and consume considerably less than at 22. Close shutters and blinds during the hottest hours, because a room already in shade needs half the cooling effort. Use the dehumidification mode on hot but not scorching days: it removes the humidity that makes heat feel sticky and costs less to run than full cooling. Clean the filters every two to three weeks. It is free and efficiency recovers immediately.
Inverter versus on/off: the difference in euros
If you have an old on/off unit, part of your electricity bill is being wasted. Those units start at full power, reach the set temperature, shut off and immediately restart at full blast: every restart is a consumption spike. An inverter unit modulates its output and keeps the room at a steady temperature without sudden surges. Over a summer of regular use the difference between an old on/off unit and a good inverter in class A+++ can be 30 to 40 percent less electricity.
When replacing the unit makes financial sense
If your split is over ten years old, runs on/off and sits in a low energy class, it is probably costing you more each summer than you realise. A quick calculation: with heavy use, a new efficient unit typically recovers the consumption cost difference in two to three seasons and delivers more silence and comfort along the way. In our air conditioners section you will find inverter models in high energy classes with the declared annual consumption listed, so you can compare the numbers before deciding.