Abstract: An additional part to be located in an air vent and an air vent for a ventilation system including a number of elements, which air vent lets air enter the ventilation system and/or move away from the ventilation system. The additional part of the air vent includes one or several sensors measuring parameters related to air quality, a data transfer interface for implementing data transfer between the air vent and other elements of the ventilation system, and a processing unit which is automatically configured to determine changes needed in the settings of the ventilation system on the basis of parameters measured by the sensors and send information on the changes needed in the other elements of the ventilation system through the data transfer interface.