It´s highly recommended to check the quality of the air tightness installation by doing a so called "air tightness test".
Ideally when the installation of the complete air tightness layers is finished and the access to these layers (e.g. window tapes & air tightness membranes is still available.
To check the completeness of the air tightness layers and to allow the repair/ upgrade of damages & leaks.
By using a blower door machine to create a negative pressure inside of the building. The leakage detection can be performed by using devices like Anemometer, Smoke Machine or Thermal Imaging Camera.
What values should be considered?
Don´t be focused too much to values like air permeability and air changes. The main attention should be taken to the detection and sealing of existing leakages.
Is this test the same like the one for BER?
No. The one for the BER inclusion has to be done when the house is finished, to measure the final values. This test is more or less the quality control for your air tightness strategy and installation work.