You don't need a subscription to use this feature. The electronic sensor in the ViCare Radiator Thermostat detects when the room temperature drops sharply. At this moment, all radiator thermostats close the heating valves and heat transfer is stopped in this room for 30 minutes. You don't have to worry about losing too much energy when ventilating. If you leave the window open, you will see “00” instead of the temperature on the ViCare radiator thermostat. The Savings Assistant users receive a push notification.