A ventilation unit with increased waste heat dissipation, with possibility of heating and/or cooling of a building having an interior and an exterior , comprising at least one fresh air input from exterior and at least one input of exhaust air from interior and comprising a passive module containing at least one passive heat air exchanger , where this passive module has at least two inputs comprising a first input (INP1) and a second input (INP2), and at least two outputs comprising a first output (OUTP1) and a second output (OUTP2), and an active module comprising at least one active heat air exchanger , where this active module has at least two inputs comprising the first input (INP1) and the second input (INP2), and at least two outputs comprising the first output (OUTP1) and the second output (OUTP2), wherein the passive module is at its first input (INP1) connected to at least one of fresh air inputs from exterior and at its second input (INP2) connected to at least one of inputs of exhaust air from interior and its first output (OUTP1) is interconnected with a first input (INA1) of the active module and its second output (OUTP2) is interconnected with a second input (INA2) of the active module , wherein each active heat exchanger comprises at least one heat modifier and two separate chambers comprising first chamber and second chamber , wherein each first chamber of each active heat air exchanger has a first chamber input (22.1) and a first chamber output (22.2) and each second chamber of said active heat air exchanger has a second chamber input (23.1) and a second chamber output (23.2), wherein further the input (22.1) of at least one first chamber is directly or via other elements interconnected with the second input (INA2) of the active module and the output (22.2) of at least one first chamber is directly or through other elements interconnected with at least one exhaust air output to the exterior and wherein the input (23.1) of at least one second chamber is interconnected directly or via other elements with the first input (INA1) of the active module and the output (23.2) of at least one second chamber is directly or via other elements interconnected with at least one air output to the interior characterized in that the ventilation unit is equipped with a second air duct for supplying additional air from the exterior which is interconnected at its first end with at least one fresh air input from the exterior and at its second end interconnected to a second input (INA2) of the active module . at its first input (INP1) connected to at least one of fresh air inputs from exterior and at its second input (INP2) connected to at least one of inputs of exhaust air from interior and its first output (OUTP1) is interconnected with a first input (INA1) of the active module and its second output (OUTP2) is interconnected with a second input (INA2) of the active module , the output (22.2) of at least one first chamber is directly or through other elements interconnected with at least one exhaust air output to the exterior and wherein the input (23.1) of at least one second chamber is interconnected directly or via other elements with the first input (INA1) of the active module and the output (23.2) of at least one second chamber is directly or via other elements interconnected with at least one air output to the interior <EOS>