State of the Art Multiple-Fan Airtightness Measurements

There is increasing recognition of the importance of quantifying the airtightness of large commercial and residential buildings. Often these tests must be performed with multiple fans and technicians, usually within a narrow time window. Despite the best preparations, surprises and interruptions are unfortunately the norm. It is therefore critical to streamline the hardware and software. Challenges to be overcome include time varying and spatially non-uniform envelope pressures and the need to simultaneously capture multiple fan flow readings. It is also necessary to analyze the results quickly enough to decide when testing is complete and whether the results meet the test requirements. The solution described consists of several computer-controlled digital manometers accessed by a single computer in real time. Fan speeds can be computer-controlled. The data and annotations are recorded into a single time-series data file. The user can easily see large deviations in building pressures due to wind, door openings, etc. and can then graphically create and edit "periods of record" (the data to be included in the test results). Within the software a standard log-log airtightness regression is performed on total fan flow versus average building pressure. Other features are available for exporting data and exploring the data graphically.