Modelling building airtightness pressurisation tests with periodic wind and sharp-edged openings

摘要

This paper presents an approach to model building airtightness pressurisation tests and to quantify uncertainties due to a periodic wind. Our approach assumes the building under test can be represented as a single zone with two sharp-edged openings, one on the windward side and one on the leeward side of the building. We detail the system of equations obtained which deals with stack effect, air compressibility, and inertia of the air subjected to unsteady pressure conditions at the boundaries of the openings. Solving the system of equations gives the dynamic behaviour of the airflow rates and state variables in the enclosure and in the leaks, making it possible to estimate the uncertainty of the air leakage coefficient in one-point pressurisation tests. Our analyses show that: (a) the wind fluctuations can yield much larger uncertainties on the air leakage coefficient than the average wind alone; (b) the wind frequency influences significantly the uncertainty when it is smaller than the sampling frequency; and (c) the contribution of the zero-flow pressure uncertainty to the uncertainty of leakage airflow rate error is of about the same size as that of the flow and pressure uncertainties at the pressure measurement station. (C) 2019 Elsevier B.V. All rights reserved.