Testing a method for the evaluation of the airtightness of ventilation systems in existing buildings

The airtightness of ventilation ductwork is an important element of the global performance of ventilation systems. Nevertheless, it is too often neglected in practice.Today, the new French Thermal Regulation (RT2000) encourages taking it into account as the energy losses calculation includes an additional part which is directly related to the additional air flow through ductwork leakages.If we want to improve the results and the practice, we have to take into consideration the whole ventilation installation : the ducts and accessories, of course, but also the connections between ducts and air terminal devices, the connections between ducts and fan units, the characteristics of these fans, CTA, etc. We also have to take into account the reality of the building site.This paper shows how to implement a methodology for measuring, on site, the global airtightness of ventilation installations. It is based on real applications on commercial and residential buildings, in France. It shows the feasibility of the method and, notably, the difficulties which were encountered for the investigations in multi-family buildings.Measurements results are given and compared to the standard classes. They show the poor quality of airtightness on the most of installations which were tested. These results are in agreement with previous studies.In parallel, this work enables to identify some of the causes of the low airtightness of ventilation systems.