The airtightness just after the end of a building phase is assumed to be relevant criteria for high energy performance. Testing on site the initial performance of the airtightness via the blower door test has become nowadays a common practice but generally implemented before the occupation of the building. What about the influence of ageing on the airtightness? Many questions exist on the durability of this initial performance. Even if retesting a building a few years after the initial test can provide a general view on the evolution of this performance, this could generate the adding cost and couldn't give information on the origin of potential changes. Another approach may be to validate technology and building technics as sustainable solutions. In order to quantitatively evaluate the durability of the airtightness of building elements as well as building technics, a research realized in Belgium has tested in laboratory the initial performance of more than 50 building walls and their materials. This performance has afterwards been tested after an accelerated ageing process including a.o. exposure to wind cycles (storms) corresponding to 10, 25 and 40 years of lifetime. The paper presents the main results of this research and points out the principal recommendations to assure the sustainability of energy performances.