Today we discover together the role of ventilation systems in cogeneration plants and we do it with Ziehl-Abegg, a leader in the field of ventilation. In particular, we will see two models of axial fans installed in a cogeneration module that powers the Granarolo plant in Usmate Velate (Italy). Fans that play the delicate role of thermoregulation of the processes and whose efficiency and reliability allow to improve the performance, energy consumption and management costs of the system.