According to examples a system, a method and a computer program for controlling at least one indoor environmental condition of a room, comprising: At least one processor, and at least one memory storing program instructions that, when executed by the at least one processor, cause the apparatus to: Receive data of a number of persons within the room. Receive second data of a clothing of the persons. Based on the first and the second data, send a signal to at least one hvac de-vice of the room configured to control a level of a cleanness of the indoor environmental condition.