An autonomous ventilation system includes a variable-speed exhaust fan, a controller, an exhaust hood, and an infrared radiation (“IR”) sensor. The exhaust fan removes air contaminants from an area. The controller is coupled to the exhaust fan and adjusts the speed of the exhaust fan. The exhaust hood is coupled to the exhaust fan and directs air contaminants to the exhaust fan. The IR sensor is coupled to the controller, detects changes in IR index in a zone below the exhaust hood, and communicates information relating to detected changes in IR index to the controller. The controller adjusts the speed of the exhaust fan in response to information relating to detected changes in IR index. The autonomous ventilation system also includes an alignment laser to indicate a point at which the IR sensor is aimed and a field-of-view (“FOV”) indicator to illuminate the zone in which the IR sensor detects changes in IR index.