Guide · Air conditioner
Saving money with your air conditioner: running costs and the right temperature
In summer keep it between 26 and 28 degrees, in winter around 20, with shutters and windows closed, clean filters and a clear outdoor unit. To get an idea of the running costs: a recent 9,000 BTU split in class A+++ uses on average about 0.3 kWh for each hour of cooling, which is about 13 cents at the ARERA reference price of October 2026.
15 minutes Difficulty: EasyUpdated 25 October 2026
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How much an air conditioner uses: the calculation
The figure to look for is the annual consumption on the energy label. ENEA reminds us that this value is calculated on 350 hours of cooling and 1,400 of heating: dividing by the hours gives you an estimate of how much it uses in an hour of running.
A real example: the 2.5 kW Daikin Perfera, about 9,000 BTU, is certified in class A+++ with 101 kWh a year in cooling. 101 kWh divided by 350 hours gives about 0.29 kWh per hour. At 43.43 cents per kWh, the ARERA reference price from 1 October 2026 including taxes for vulnerable households under Maggior Tutela, that is about 13 cents an hour. At 8 hours a day that makes about 2.3 kWh and 1 euro, or about 60 euros over two summer months.
It is an estimate: in the hottest hours, with the sun on the outdoor unit, it uses more, on cool evenings less. You find your own price on your bill and, if it is lower, the cost falls in proportion. An old split weighs more: according to ENEA a class A+++ model uses up to 40% less than a class B one.
Does it use more in cooling or in heating?
For each hour of running, it usually uses more in heating. In winter the difference between inside and outside is larger, and the seasonal efficiency in heating, the SCOP, is generally lower than the one in cooling, the SEER.
On the same Daikin, the label shows 659 kWh a year in heating over 1,400 hours: about 0.47 kWh an hour, or about 20 cents at the same price. In cooling it was 0.29 kWh. The label's heating hours follow a European reference season: on the Campania coast, with milder winters, they are usually fewer.
For heating, the heat pump remains an efficient system: with a COP of 4, for example, for each kWh of electricity it brings four kWh of heat into the home. The comparison with a boiler depends on the electricity and gas rates you pay.
Why the air conditioner uses so much
The most common causes are simple: dirty filters, the outdoor unit in the sun or shut in a recess, the temperature set too low, open windows. A split that is too small for the room also runs flat out all the time, and old units without an inverter, which switch on and off at full power, use more than those that adjust the compressor to the need.
If consumption rises from one year to the next and it cools less, gas may be missing because of a leak, or the indoor coil may be covered in dirt. The compressor runs longer to give the same cooling. This is where DIY ends: for the gas you need an engineer with F-gas certification to find the leak.
There is also a legal reference on temperature: DPR 74/2013 says not to go below 26 degrees in summer and not to exceed 20 in winter, in both cases with 2 degrees of tolerance.
When to stop and call a technician
- Consumption rises from one season to the next and the split cools less and less
- The outdoor compressor keeps switching on and off, every few minutes
- Frost or ice on the outdoor unit's pipes while cooling
- The split never reaches the set temperature, even with clean filters and closed windows
- The outdoor unit sits in a closed recess or in the sun all day and needs to be moved
Frequently asked questions
How much does an air conditioner use per day?
A recent 9,000 BTU split in class A+++ uses about 0.3 kWh an hour in cooling: in 8 hours about 2.3 kWh, which is around 1 euro at the ARERA reference price of October 2026. An old or lower-class model uses more.
What is the ideal air conditioner temperature?
In summer 26-28 degrees, or two or three degrees below outside. In winter around 20 degrees, which is also the limit given by DPR 74/2013, with 2 degrees of tolerance.
Does the air conditioner use more in cooling or heating?
Per hour of running, usually in heating, because in winter the temperature difference with the outside is greater. In this guide's example: 0.29 kWh an hour in cooling, 0.47 in heating.
Why does my air conditioner use so much?
Check the filters, the outdoor unit, the temperature setting and the windows. If everything is fine and it cools less than before, have it checked: gas may be missing or the coil may be dirty.
Is it worth switching it off when I go out?
If you are out for a few hours, yes: switch it off, leave the shutters down and use the timer to switch it on shortly before you return. ENEA advises exactly this, to cut running time to a minimum.
Does the air conditioner use less in dehumidifying mode?
Often yes, because the fan and compressor work more gently, but it depends on the model. The bigger advantage is that with less humidity you feel fine at a higher temperature.
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