A flow measurement unit for measuring a rate of airflow for a ventilation system. The flow measurement unit includes a flow measurement device installed in a housing. A first and a second pressure gauge are provided anteriorly and posteriorly, respectively, to the flow measurement device. The first and the second pressure gauge are configured to provide a first pressure reading, corresponding to the first pressure, and a second pressure reading, corresponding to the second pressure of airflow. Further, the flow measurement unit includes a fan to adjust airflow, such that the second pressure approaches the first pressure of airflow.