Building airtightness is becoming of increased importance in many European countries. Several countries pay attention to building airtightness in their regulation and sometimes even impose a minimum performance. For passive houses is the achievement of a very good airtightness level an absolute requirement. In order to exchange experiences and to show new developments by industry, there will be on October 1 and 2 the international BUILDAIR symposium (previously called Blowerdoor symposium) in Berlin which will be combined with an exhibition. This symposium is also combined with the 30th AIVC conference.