On the integration of envelope pressure inhomogeneity and autocorrelation in fan pressurization uncertainty analysis

Improving the knowledge on uncertainty for fan pressurization measurement is of first importance. It allows to assess the reliability of the measurement, which is essential when comparing the results with benchmarks or standards, but it also gives a better understanding, and thus a chance of improving, the measurement procedure. In this context, recent studies on alternative regression techniques highlights the importance of identifying and quantifying the sources of uncertainty. This paper investigates the integration of two new aspects in the measurement procedure: an uncertainty source related to the inhomogeneity of pressure difference along building envelope, and the autocorrelation of successive pressure difference measurement due to wind fluctuations. Those are integrated in the framework of uncertainty calculation and are then applied to a series of 30 tests conducted in repeatability conditions in an apartment in Brussels. Results show the relatively low impact of those additions to the determination of building characteristics (n, c_env, q₅₀)and their large impact on both results variability and uncertainty assessment.