Leaving air conditioning running continuously costs 24 cents over four hours compared to 45 cents when toggled repeatedly, according to a technology expert in Madrid.
The findings, reported by Ignacio Juanilla Bernardo on August 22, 2026, challenge the widespread belief that switching off a cooling unit whenever leaving a room or home reduces electricity expenses.
Energy consumption during continuous operation
Data from power consumption tests show that turning an air conditioner on and off can nearly double energy expenses while reducing indoor comfort.
When an air conditioner is first turned on, the apparatus operates at maximum power for approximately one hour to cool the room, consuming between 1 and 1.2 kilowatt hours of electricity.
Once the space reaches the targeted temperature, the compressor reduces its output significantly and enters a low energy maintenance mode, dropping power consumption to approximately 300 watt hours.
This maintenance phase results in an operational cost of 3 to 4 cents per hour. The technology expert calculated that leaving the unit running continuously for four hours keeps a home cool for about 24 cents while maintaining a stable indoor temperature without power spikes.
Why frequent switching increases power costs
In contrast, switching the cooling unit off and on repeatedly forces the compressor to work at maximum capacity each time it restarts to cool air that warmed while the system was inactive.
The technology expert explained that turning the equipment off and on three times over a four hour period causes indoor temperatures to vary constantly and raises total power costs to 45 cents.
Air conditioning compressors drive cooling systems by circulating refrigerant, and frequent start cycles subject these mechanical components to repeated peak power demands.
Based on these calculations, continuous operation is the most efficient choice for short absences or when remaining at home for several hours. Turning off the equipment is only recommended for long absences lasting many hours or days, when saved maintenance energy exceeds the cost of starting power spikes.
Health guidance and alternative cooling options
Alongside energy considerations, health experts have issued guidance on air conditioner settings during environmental hazards. Pneumologists advised closing windows tightly and running air conditioning units in recirculation mode, noting that wildfire smoke particles can travel long distances even when smoke is not visible outdoors.
Recirculation mode filters and cools existing indoor air rather than drawing outside air into the building.
Energy analysts also highlighted cost differences between air conditioning systems and basic electric fans. Jaime Pla, an industrial engineer, stated that running a fan all night throughout July costs 1.30 euros, whereas operating an air conditioner over the same month can cost more than 50 euros.
Energy expert Xavi noted that using an air conditioner for eight hours a day can result in a monthly electricity bill of up to 54 euros, compared to two euros for operating a fan.
The report was produced by the editorial team with assistance from artificial intelligence tools.
