A method of operating an active controlled atmosphere system to regulate the atmosphere in a cargo storage space, the active CA system comprising: a plurality of gas exchange modules, each being operable to vary the level of a respective component gas in the cargo storage space, and/or at least one gas exchange module operable in a plurality of different modes to vary the level of a respective component gas in the cargo storage space; and a control module configured to control operation of each gas exchange module according to a plurality of different predetermined atmospheric control logics, wherein each atmospheric control logic defines operational gas exchange modules and/or operational modes for use over respective operational ranges of atmospheric conditions, and each atmospheric control logic is configured to cause operation of a different combination of gas exchange modules and/or modes over a comparable operational range, independently of any setpoints for gas component levels; and wherein the method comprises: the control module receiving an input indicative of the nature of the goods stored in, or to be stored in, the cargo storage space, the control module selecting an operational atmospheric control logic from the plurality of different predetermined atmospheric control logics for atmospheric control of the cargo storage space, based on the input; and the control module controlling operation of each gas exchange module dependent on the selected operational atmospheric control logic to regulate the atmosphere in the cargo storage space. a plurality of gas exchange modules, each being operable to vary the level of a respective component gas in the cargo storage space, and/or at least one gas exchange module operable in a plurality of different modes to vary the level of a respective component gas in the cargo storage space; and a control module configured to control operation of each gas exchange module according to a plurality of different predetermined atmospheric control logics, wherein each atmospheric control logic defines operational gas exchange modules and/or operational modes for use over respective operational ranges of atmospheric conditions, and each atmospheric control logic is configured to cause operation of a different combination of gas exchange modules and/or modes over a comparable operational range, independently of any setpoints for gas component levels; and wherein the method comprises: the control module receiving an input indicative of the nature of the goods stored in, or to be stored in, the cargo storage space, the control module selecting an operational atmospheric control logic from the plurality of different predetermined atmospheric control logics for atmospheric control of the cargo storage space, based on the input; and the control module controlling operation of each gas exchange module dependent on the selected operational atmospheric control logic to regulate the atmosphere in the cargo storage space. the control module receiving an input indicative of the nature of the goods stored in, or to be stored in, the cargo storage space, the control module selecting an operational atmospheric control logic from the plurality of different predetermined atmospheric control logics for atmospheric control of the cargo storage space, based on the input; and the control module controlling operation of each gas exchange module dependent on the selected operational atmospheric control logic to regulate the atmosphere in the cargo storage space.