A considerable change is going on in Norwegian building industry. Due to higher ambitions in energy regulations, focus has returned to the importance of improved air tightness. A stronger need to document this property have led to one acknowledgement of much more frequent measuring of air tightness being needed. There have been different approaches to possible cost reduction for this through a series of different methods being studied. Simple equipment for measuring has been developed, as an initiative from the Norwegian building industry. Very encouraging results are beginning to manifest itself from the process of measuring, repairing defects and adjusting detailing. Different approaches to documenting air tightness by measuring are presented together with practical examples from buildings of different types.