Smart thermostat
In 2011, Nest Labs developed the Nest Learning Thermostat. The Nest Thermostat attempted to reduce home energy consumption by addressing the problems with programmable thermostats through the use of better technology. This new technology included the implementation of sensors, algorithms, machine learning, and cloud computing. These technologies learn the behaviors and preferences of the occupants, and adjust the temperature up or down to make the occupant comfortable when they are home and to save energy when they are away. Additionally, the Nest Thermostat connects to the home Wi-Fi. This allows users to change the temperature, adjust the schedule, and check energy usage from a smartphone or laptop. All of these features were part of Nest's goal to create an easy to use thermostat that saves users energy and money.
Thermostat
Water and steam based central heating systems have traditionally had overall control by wall-mounted bi-metallic strip thermostats. These sense the air temperature using the differential expansion of two metals to actuate an on/off switch. Typically the central system would be switched on when the temperature drops below the setpoint on the thermostat, and switched off when it rises above, with a few degrees of hysteresis to prevent excessive switching. Bi-metallic sensing is now being superseded by electronic sensors. A principal use of the bi-metallic thermostat today is in individual electric convection heaters, where control is on/off, based on the local air temperature and the setpoint desired by the user. These are also used on air-conditioners, where local control is required.