Device for recovering heat energy

The device (1) has an air circulation channel provided on an external surface of a pipe (2) that discharges heated fluid. The channel is configured to heat air during circulation of air between an inlet opening (13) and an outlet opening (14). A ventilation unit of the channel is configured to create forced circulation of air from the inlet opening in a direction of the outlet opening. The channel comprises a single block envelope delimiting a transit volume with respect to ambient air, and an interface layer between the transit volume and an external surface of the pipe.