In the event of a power outage, the thermostat will no longer work. However, the product is designed to work again as soon as the power is restored and return to the state it was in before the power outage. Please note that the thermostat may take a few minutes to reconnect to the Internet and be accessible via the application again. If the Internet is not active, the thermostat will continue to work locally and will follow the program set. During the outage: You cannot control the system via the Home + Control application or change the settings. You can still control and see the temperature directly on the thermostat. The same behavior as Smarther will also be performed by Netatmo Smart Radiator Valves.