Method and system operating a controlled atmosphere system

A method of operating a controlled atmosphere (CA) system to regulate the atmosphere in a cargo storage space, the CA system comprising a gas exchange module operable to vary the level of a component gas in the cargo storage space, a control module to control operation of the gas exchange module, and at least one of an oxygen sensor and a carbon dioxide sensor, each being operable to measure a parameter indicative of a level of oxygen or carbon dioxide respectively in the cargo storage space, the method comprising:

• the control module determining a respiration parameter value indicative of the rate of change of oxygen level and/or the rate of change of carbon dioxide level in the cargo storage space due to respiration of goods in the cargo storage space, wherein the respiration parameter value is determined from at least three predetermined respiration parameter values, each respiration parameter value corresponding to a respective range of rate of change of oxygen level and/or a respective range of rate of change of carbon dioxide level;
• and
• the control module controlling operation of the gas exchange module based on the determined respiration parameter value to target an oxygen level setpoint and/or a carbon dioxide level setpoint;
• and wherein the control module determining the respiration parameter value comprises:
• the control module determining a rate of change of oxygen level and/or a rate of change of carbon dioxide level in the cargo storage space due to respiration of the goods in the cargo storage space;
• and
• the control module determining the respective respiration parameter value, from the at least three predetermined respiration parameter values, associated with the rate of change of oxygen level and/or the rate of change of carbon dioxide level.