A fan doesn't actually make the room colder: it only moves air around. Yet, it feels cooler because the airflow makes sweat evaporate faster and blows away the layer of warm air around your skin. The thermometer barely changes, but you experience it as cooling.
How does a fan work?
An electric motor rotates the blades, which sets the air in motion. This happens without cooling the air itself. A fan therefore does not add cold, but provides air circulation so that warm air does not stagnate.
Why does the air feel cooler?
Your body cools itself by sweating. Moisture that evaporates from your skin extracts heat from your body. Air movement accelerates that evaporation and removes the layer of heated air around your skin. The feeling of cooling is therefore an effect on you, not on the room. A more detailed explanation can be found in Why does air from a fan feel cooling?.
When does a fan help and when does it not?
A fan helps most when you are in the airflow yourself and the air is relatively dry. If it is very humid, sweat evaporates more slowly and it feels less cool. In extreme heat, especially for vulnerable people, a fan alone may be insufficient. A fan in an empty room is hardly useful, because the device does not heat the air and does not cool it. So turn it off when you leave the room.
| Situation | Effect of a fan |
|---|---|
| Dry, warm day, you in the airflow | Noticeable cooling |
| Very humid day | Less effect |
| Empty room | No useful effect |
| Window open in the evening | Helps bring in cool air |
| Extreme heat | Often insufficient |
Smart usage
Aim the airflow at yourself, choose a setting that isn't disruptive, and use it in combination with other measures, such as blinds and ventilating in the evening. In the bedroom, it can be pleasant; see Can a fan stay on all night?. If you are doubting between a pedestal fan and a tower fan, read Pedestal fan or tower fan: which one suits you?.
Direct answer: a fan does not lower the air temperature, but makes you feel cooler because sweat evaporates faster. The effect is greatest on a dry, warm day with the airflow aimed at you.
Featured: the AirFlow AV25G pedestal fan
The Dynter AV25G is a foldable pedestal fan.
Height: adjustable from 80 to 125 cm
Oscillation: automatic, for wide air distribution
Speeds: three, using a dial
Air velocity: 5.3 m/s
Energy consumption: 55 W (AC motor)
Folded size: 42 × 42 × 20 cm, weight 3.49 kg
View the AV25G in white, the AV25G in grey or the collection of fans and air coolers. Curious about the consumption? See How many watts does a fan consume per hour?.
Frequently asked questions
Does a fan cool the air?
No, it only moves air. The cool feeling comes from evaporation on your skin.
Should I aim the fan at myself?
Yes, the effect is in the airflow over your skin. In an empty room, there is no benefit.
Does a fan work in high humidity?
Less well, because sweat evaporates more slowly then.
Can I open a window with a fan?
Yes. In the evening and at night, that can bring in cooler outside air.
Is a fan enough during a heatwave?
Not always. In extreme heat, seek additional cooling and keep an eye on vulnerable people.