Sergio Llorente, an electrical installer, said running a fan for eight hours overnight costs about two cents, based on a device that draws 21 watts and an electricity rate of 0.15 euros per kilowatt hour. He shared the calculation with his followers on Instagram.
The final cost depends on two figures: the power the fan actually takes from the grid and the price of each kilowatt hour. A fan's label shows a maximum power rating, but real consumption changes with the speed setting, the motor and whichever functions are switched on. The electricity contract, taxes and time of use also play a role, so the two-cent figure is an example rather than a guaranteed rate.
How the two cents were calculated
Llorente said the fan he analysed drew about 0.021 kW. Kept running for eight hours, that works out to 0.168 kWh. At an assumed price of 0.15 euros per kWh, the cost comes to 0.0252 euros. An air conditioning specialist noted that the way a fan is used also affects how much power it draws.
The same sum can be applied to any model: multiply the power in kilowatts by the hours of use and by the price per kWh. A 50-watt fan running at full power would use 0.4 kWh over eight hours, more than double the example. Checking the label avoids false comparisons, and some smart home platforms let users track accumulated consumption.
Over 30 nights, the 21-watt fan would total 5.04 kWh, though the final amount on the bill will vary. A plug-in energy meter lets users check the real figure without estimating, which is most useful when a fan is old or its label is unclear.
Getting the most out of a fan at night
A fan moves air but does not lower a room's temperature; the airflow speeds up sweat evaporation and improves the sensation of coolness. In intense heat, a portable air conditioner can cool the space, though it requires considerably more energy.
For sleeping, Llorente recommended the lowest comfortable speed, using the timer if the early morning cools down, and cleaning the blades, since a well-maintained fan moves air with less noise. Position can matter more than speed: near an open window during the cooler hours it helps refresh the air, while with windows shut in full heat it only recirculates it. Taking advantage of the nighttime temperature drop brings more relief with less power and less noise by the pillow, and closing blinds during the day keeps a room several degrees cooler.
He also advised placing a fan on a stable base, keeping the grille clear, replacing damaged cables, and switching it off when no one is in the room, since it will not have left the room cool. Two cents is a possible reference figure; the fan's actual measured power and the price of electricity determine the real cost.
