Individual unit and guard-zone airtightness tests of apartment buildings

The airtightness of eight apartment buildings containing six to 11 units each on three or four floors was tested with and without guard-zone pressure, that is, with and without consideration of internal leakages. The layouts of these buildings varied: two of them had no central stairwell; in two other buildings, only some of the apartments were connected to the central stairwell; and the third type had all apartments connected to a central stairwell. Airtightness tests were performed with and without guard-zone pressure conditions. During these tests, two to eight BlowerDoor systems were used simultaneously to create guard-zone pressure conditions. In this report, the authors evaluate the test results of three buildings of different layout types. Furthermore, a reference model for the natural air permeability of all construction materials used in the interior and exterior envelopes of each apartment was created for two buildings in accordance with the German Industrial Standards (DIN). We present the results of this assessment and put them in context with the airtightness tests with and without guard-zone pressure. The results indicate that the air leakage contribution of internal partitions is significant, namely 32% and 27%. As this affects sound transmission, fire protection, odor transfer, and the quality of ventilation, it is essential to assess the airtightness of not only the exterior but also the interior envelope of each apartment.