Air flow control unit, system for ventilation system of building and method for controlling ventilation of building

An air flow control unit for controlling air flow in a duct, comprising a damper, which is arranged to be installed to the duct, comprising:

• an inlet side, from which the air flow enters the damper;
• an outlet side, from which the air flow exits the damper;
• and
• at least one damper blade, arranged between the inlet side and the outlet side, configured to rotate about an axis perpendicular to the air flow direction,
• wherein the air flow unit comprises a measurement unit comprising at least two measurement areas so that one measurement area is arranged on different side of the damper in air flow direction than another measurement area, wherein each measurement area comprises at least one measurement probe having a measurement point for measuring pressure,
• wherein the first measurement area is arranged on the inlet side of the damper, and the first measurement area comprises a first measurement probe having a first measurement point, and a first wall behind the first measurement point in air flow direction causing a change in the air flow at the first measurement area.