Abstract: A duct for air transport comprises an inner jacket having an inlet end for connecting the duct to an air supply and an outlet end for connecting the duct to a duct for a further transport or distribution of air, and an outer jacket made of an impervious material and surrounding the inner jacket spaced therefrom. An insulating chamber is formed between the inner jacket and the outer jacket. The inner jacket and the outer jacket are adapted to conduct from the interior space of the inner jacket through the insulating chamber into the ambient atmosphere, namely in an amount of 0.02 to 100‰ of the total volume of air fed into the inner jacket. The area for conducting air into the insulating chamber and the area for conducting air away from the insulating chamber are spaced from each other during the operation of the duct.