Air tightness is a fundamental pillar for every energy-efficient building. But how can we ensure a high level of quality, and what needs to be taken into account? The webinar dives into the process of a "blower door measurement" to check the airtightness on the building site, including leakage detection. Wolfgang Hasper from the Passive House Institute will not only explain how to set up a blower door test but also talk about common mistakes and ways to avoid them. The presentation will also explain how to calculate the characteristic value and classify the measurement result.