When the main system starts working either on cooling or heating, it takes a few minutes until the warm/ cool air gets to the room that the device is installed. During this time if the SmartCoocoon device starts working, it will boost unconditioned air into the room and that can cause the room to get even colder in the winters. So the device will monitor the temperature and starts to boost the air only when the temperature of the air coming from the vents gets to the level that is actually effective to make a difference. The same scenario happens when the main system is turned off. Although the cooling/ heating system is off still there is some conditioned air in the ducts that can be sucked out and help more to get the room to the desired temperature.