Wind tightness prevents air moving into the building from outside. The wind tight membranes are being installed in the external part of the construction and are protecting it from cooling and dampness.
Why is it important?
To achieve maximum thermal efficiency the insulation must be completely sealed on both sides.
The insulation is now protected against the elements on the outside by the Proctor external breather membranes and on the inside by the airtight seal (e.g. vapour check) in this case the Gerband membrane. The construction is wind-tight externally and air-tight internally, what keeps the insulation nice and cosy, giving it every opportunity to work effectively.