Humidity-controlled ventilation supply elements for room air exchange. They guarantee a variable air supply of 6-45 m3/h depending on the relative humidity, with a pressure difference of 20 Pa, which partially eliminates cross ventilation, which is the main cause of energy waste. The element is made of injection moulded polystyrene and consists of an external louvre and an internal part with a silencer. The element is installed in a prepared hole of 354 × 12 mm in the window frame using screws.