A method of detecting a condition in an exhaust ventilation system including an exhaust hood, the method comprising: receiving, at a control module, an exhaust air temperature signal representing a temperature of the exhaust air in a vicinity of the exhaust hood, the exhaust air temperature signal being generated by an exhaust air temperature sensor; receiving, at the control module, a radiant temperature signal representing a temperature of a surface of a cooking appliance that generates the exhaust air, the radiant temperature signal being generated by a radiant temperature sensor; receiving, at the control module, a pressure signal representing the pressure in the exhaust hood; regulating a flow of exhaust to a first flow rate associated with an idle status of the cooking appliance responsively to the received exhaust air temperature signal, the received radiant temperature signal, and the received pressure signal; regulating a flow of exhaust to a second flow rate, higher than the first flow rate, associated with a high load cooking status of the cooking appliance responsively to the received exhaust air temperature signal, the received radiant temperature signal, and the received pressure signal; regulating a fire suppression mechanism responsively to at least one of the received exhaust air temperature signal, the received radiant temperature signal, and the received pressure signal, using said control module, and responsively to said radiant temperature, exhaust temperature, and an optical luminance signal, distinguishing a flare-up from a grill from a fire; and regulating a flow rate of the exhaust and/or regulating a fire suppression mechanism responsively to the distinguishing. receiving, at a control module, an exhaust air temperature signal representing a temperature of the exhaust air in a vicinity of the exhaust hood, the exhaust air temperature signal being generated by an exhaust air temperature sensor; receiving, at the control module, a radiant temperature signal representing a temperature of a surface of a cooking appliance that generates the exhaust air, the radiant temperature signal being generated by a radiant temperature sensor; receiving, at the control module, a pressure signal representing the pressure in the exhaust hood; regulating a flow of exhaust to a first flow rate associated with an idle status of the cooking appliance responsively to the received exhaust air temperature signal, the received radiant temperature signal, and the received pressure signal; regulating a flow of exhaust to a second flow rate, higher than the first flow rate, associated with a high load cooking status of the cooking appliance responsively to the received exhaust air temperature signal, the received radiant temperature signal, and the received pressure signal; regulating a fire suppression mechanism responsively to at least one of the received exhaust air temperature signal, the received radiant temperature signal, and the received pressure signal, using said control module, and responsively to said radiant temperature, exhaust temperature, and an optical luminance signal, distinguishing a flare-up from a grill from a fire; and regulating a flow rate of the exhaust and/or regulating a fire suppression mechanism responsively to the distinguishing.