A system for inerting a fire at an indoor location, the system comprising: - a source of an inerting gas void of oxygen or having a first concentration of oxygen; - a control system for controlling release of the inerting gas into the indoor location; - at least one fire detector connected to the control system for detecting a fire and/or signs of a fire at and/or near the indoor location; and - at least one sensor configured for detecting at least one condition at and/or near the indoor location other than a condition indicative of the presence of a fire, characterised in that if the at least one condition is an air pressure at or near the indoor location, then the control system is configured to: - compare a detected pressure with a first threshold pressure, - deliver a first amount of inerting gas to the indoor location if the detected pressure is above the threshold pressure; and - deliver a second amount being larger than the first amount of inerting gas to the indoor location if the detected pressure is below the first threshold pressure; and/or if the at least one condition is an open-or-closed state of a closable path into the indoor location, then the control system is configured to: - deliver a first amount of inerting gas to the indoor location if the closable path is closed; and - deliver a third amount being larger than the first amount of inerting gas to the indoor location if the closable path is open; and/or if the at least one condition is a flow of air at or near the indoor location, then the control system is configured to: - deliver a first amount of inerting gas to the indoor location if the detected flow of air is below a first threshold flow; and - deliver a fourth amount being larger than the first amount of inerting gas to the indoor location if the detected flow of air is above the first threshold flow. - a source of an inerting gas void of oxygen or having a first concentration of oxygen; - a control system for controlling release of the inerting gas into the indoor location; - at least one fire detector connected to the control system for detecting a fire and/or signs of a fire at and/or near the indoor location; and - at least one sensor configured for detecting at least one condition at and/or near the indoor location other than a condition indicative of the presence of a fire, - compare a detected pressure with a first threshold pressure, - deliver a first amount of inerting gas to the indoor location if the detected pressure is above the threshold pressure; and - deliver a second amount being larger than the first amount of inerting gas to the indoor location if the detected pressure is below the first threshold pressure; and/or - deliver a first amount of inerting gas to the indoor location if the closable path is closed; and - deliver a third amount being larger than the first amount of inerting gas to the indoor location if the closable path is open; and/or - deliver a first amount of inerting gas to the indoor location if the detected flow of air is below a first threshold flow; and - deliver a fourth amount being larger than the first amount of inerting gas to the indoor location if the detected flow of air is above the first threshold flow.