It is enough up to around 31 to 32 °C ambient temperature. Beyond that, hot air blown onto the skin becomes counterproductive: sweat can no longer evaporate efficiently, and the sensation of heat increases rather than decreases. In a typical French hot season, half the discomfort hours remain below this threshold and can therefore be managed perfectly with a fan or ceiling fan. For the season's hottest 20 to 30 hours (peaks above 35 °C), an evaporative cooler in a dry climate or a split air conditioner in a humid climate becomes necessary.
Read the source article: Alternatives to air conditioning: 4 solutions compared