A method and a system for the preparation of compressed air having a heat exchanger (system heat exchanger) which is in communication with a pressure source on the inlet side on the compressed air side and which is in communication with a system or unit on the outlet side on the compressed air side which is to be supplied with cooled compressed air and including at least one heat exchanger (air conditioning system heat exchanger) which is in communication with a pressure source on the inlet side on the compressed air side and which is in communication with additional components of an aircraft air conditioning system on the outlet side on the compressed air side. Provision is made for the system heat exchanger and the at least one air conditioning system heat exchanger to have a common inlet for supply with ram air or environmental air and for the system heat exchanger to be connected on its outlet side on the compressed air side via a closable line to the line system on the compressed air side in communication with the at least one air conditioning system heat exchanger or to the at least one air conditioning system heat exchanger itself.