The Ecobee smart room sensors provide the thermostat with a window into the climate status within areas of your home that wouldn't normally be controlled. For instance, if you place it in an office, you can see the temperature in the office in the Ecobee app. You can name the sensors whatever you'd like. The thermostat calculates the average temperature throughout the home using these sensors. It then uses the result to determine how much or little to control the climate in that room in order to keep it within the range set at the thermostat.In addition, it can tell if someone is using the room where it's located in order to save power. Not in the room? Ecobee disregards the averaging feature for that room. Once someone enters, it begins again.They're very easy to use. There is no need to turn them on or off. They are extremely sensitive and reliable, and they have a very clean design.