To provide a ventilation system carrying out exhaust or air supply by a fan to efficiently prevent a portion easily causing dew condensation in a room.
The ventilation system is provided with the fan 5 carrying out exhaust or supply of air of the room, a temperature detecting means 7 installed in at least two places of the room to detect temperatures, and a calculating means for calculating an air vapor amount included in the room from a relationship of humidity and a temperature detected by a humidity detecting means 8 for detecting humidity of the room, and calculating a temperature difference saturating water vapor and reaching dew condensation. When it is judged that the temperature difference will cause dew condensation, exhaust or air supply is carried out by the fan 5 to prevent dew condensation in the room.
Hiroki Naito
Daisuke Nagano