Method for low-temperature air separation, in which an air separation unit (100-3100) having a first rectification column and a second rectification column is used, - the first rectification column being operated at a first pressure level and the second rectification column being operated at a second pressure level below the first pressure level, - fluid which is oxygen-enriched compared to atmospheric air being drawn from the first rectification column in the form of one or more first material flows, - at least one portion of the fluid drawn from the first rectification column in the form of the one or more first material flows being heated in a heat exchanger , - a portion of the fluid heated in the heat exchanger being compressed using a compressor and returned to the first rectification column , - a first portion of the head gas of the first rectification column being condensed in the heat exchanger and a second portion being discharged from the air separation unit in the form of at least one nitrogen-rich air product, - additional fluid containing oxygen, nitrogen and argon being drawn from the first rectification column and used as a second material flow or to form a second material flow which is transferred to the second rectification column , and - an oxygen-rich sump liquid being formed in the sump of the second rectification column and at least one portion thereof being discharged from the air separation unit in the form of a third material flow, characterized in that - a third rectification column is used, the second rectification column and the third rectification column being designed as parts of a double column, the third rectification column being arranged below the second rectification column , and the third rectification column being supplied with air. - the first rectification column being operated at a first pressure level and the second rectification column being operated at a second pressure level below the first pressure level, - fluid which is oxygen-enriched compared to atmospheric air being drawn from the first rectification column in the form of one or more first material flows, - at least one portion of the fluid drawn from the first rectification column in the form of the one or more first material flows being heated in a heat exchanger , - a portion of the fluid heated in the heat exchanger being compressed using a compressor and returned to the first rectification column , - a first portion of the head gas of the first rectification column being condensed in the heat exchanger and a second portion being discharged from the air separation unit in the form of at least one nitrogen-rich air product, - additional fluid containing oxygen, nitrogen and argon being drawn from the first rectification column and used as a second material flow or to form a second material flow which is transferred to the second rectification column , and - an oxygen-rich sump liquid being formed in the sump of the second rectification column and at least one portion thereof being discharged from the air separation unit in the form of a third material flow, - a third rectification column is used, the second rectification column and the third rectification column being designed as parts of a double column, the third rectification column being arranged below the second rectification column , and the third rectification column being supplied with air. <EOS>