The thermostat, a device that regulates indoor temperature, has evolved significantly in recent years. Once a simple mechanical tool, modern thermostats are now "smart" devices that connect to the internet and can learn from user behavior to optimize energy use. Nest, a pioneer in this field and now owned by Google, has led the way in this shift. A new French decree, effective January 1, 2027 for new homes and January 1, 2030 for existing ones, mandates the installation of an automatic temperature regulation system. While a basic programmable thermostat meets this requirement, many consumers are opting for connected models that offer additional features and energy savings. Among the popular connected thermostats is the Tado° X, which is compatible with most heating systems. It connects via a mobile app and offers features like geolocation, which adjusts the temperature based on your smartphone’s location. Advanced features such as open window detection and AI learning require a subscription. The Tado° V3+ includes an internet bridge and is compatible with Google Assistant, Alexa, and Apple HomeKit. It can also detect heating system malfunctions and provide energy usage reports. Accessories are available to expand compatibility with different heating systems. Sowee, a subsidiary of EDF, offers a connected thermostat as part of an energy contract. The system includes a connected station that displays air quality, weather, and even travel time. It also includes Alexa for voice control, similar to an Amazon Echo. However, additional costs apply for extra kits, and it is only effective with electric radiators, not conventional boilers. While it offers comprehensive features, the cost and energy savings depend on the home's insulation and other factors. Netatmo Thermostat, a French product acquired by the Legrand Group, is compatible with various heating systems and can be controlled via smartphone, voice assistants, and even Facebook Messenger. It adjusts based on outside temperature and living habits, and includes features like auto-care for battery and system alerts. It also integrates with other Netatmo devices and is available at a relatively low price. Somfy Thermostat V2 offers a complete solution with remote control and geolocation features but lacks some sensors found in other models. It provides compatibility checks and a network of installers. Google Nest, once a major player in connected home devices, is no longer supported in Europe due to recent company changes. While it was once a strong option, it is no longer recommended. Thermostat heads are available for those without compatible boilers, with options like Tado° and Eve Thermo. These can be installed on radiators for individual temperature control, though some models are more suited for specific ecosystems like Apple HomeKit. Connected thermostats help stabilize indoor temperatures and reduce energy consumption, leading to lower bills. While installation can be complex, many manufacturers provide guides and support. The savings vary, but on average, households can save between 50 to 150 euros annually. Compatibility with heat pumps depends on the type, and users should always check their system's manual before purchasing.