Outside Air Temperature (Oat) 

Outside air temperature (OAT) is a measurement of the temperature of the air surrounding a building. OAT is used in weather-sensitive control systems, such as those that regulate heating, ventilation, and air conditioning (HVAC) systems, to ensure that the indoor environment remains comfortable. OAT sensors are typically located on the roof or outside wall of a building.

The sensor readings are transmitted to the control system, which then adjusts the indoor temperature accordingly. In some cases, OAT can also be used to determine when windows should be opened or closed to ventilate a space.