Abstract: A smart ventilation system which performs the ventilation of indoors, increases the air quality in closed spaces and maintains air quality, which is positioned over a window and includes: a ventilation module on a main body, which is attached to the window so as to control the air passage between indoors and outdoors; indoor and outdoor sensor groups which measure the air values indoors and outdoors, respectively; and an electronic card which analyzes the sensor values and engages one or more of an air intake fan group, an air outlet fan group, a dehumidifier, and a humidifier as a result of the analysis. A device provides the necessary energy from the adaptor and water reservoir.