Abstract: The invention relates to a method for air separation by cryogenic distillation in a column system that includes at least a first column operating at a first pressure, and a second column operating at a second pressure that is lower than the first pressure, the head of the first column being thermally connected to the tank of the second column via a vaporizer-condenser, a first portion of a nitrogen-enriched gas is drawn from the head of the first column, compressed in a compressor having an inlet temperature no higher than ?150° C. and condensed in the vaporizer-condenser, an oxygen-rich fluid is drawn from the lower portion of the second column and heated in the exchange line, a nitrogen-rich gas is drawn from the upper portion of the second column and heated in the exchange line, and a second portion of the nitrogen-enriched gas is expanded in a turbine without being compressed.