Abstract: The object of the invention is an air supply unit (1) for recovering heat energy from an air stream (e.g., exhaust air) and transferring the heat energy to another air stream (e.g., supply air). The air supply unit (1) comprises a casing (25), in the casing (25) an exhaust air channel (4) for leading exhaust air (2) through the casing (25) of the air supply unit (1), in the casing (25) a supply air channel (7) for leading supply air (7) through the casing (25) of the air supply unit (1), and in the casing (25) a heat exchanger (10) for transferring heat energy between the exhaust air (2) flowing in the exhaust air channel (4) that leads through the casing (25) and the supply air (3) flowing in the supply air channel (7). In the casing (25), the air supply unit (1) comprises a heat pump (11) having a first heat interchanger (12) having a first interior for refrigerant, and a second heat interchanger (13) having a second interior for refrigerant.