The trend in European countries, such as Belgium, France and Germany is that the quality of the airtightness of the building envelope is getting better and better. This is true for small, airtight apartments, Passive houses and some large buildings with an excellent airtightness due to special requirements, e.g. oxygen reduction or fire protection. This good quality leads to new challenges in the performance of airtightness tests: Knowledge about an adapted way of measuring with a lot of patience. What has to be taken into account in order to perform measurements of very airtight buildings? The different causes, solutions and tips are presented in this paper.
