Uncertainty of climate related parameters of a building envelope – case of leakage characteristics

Paper in proceeding, 2014

Airflow through the building envelope depends on the airtightness of the structure specified by the type of construction and the quality of the workmanship. If we neglect the latter reason, the actual airtightness performance of the building depends on the regime of the airflow through the openings which is a combination of laminar and turbulent ones. The leakage characteristics of a building vary according to the changes of the regime of the flow with the pressure difference across the building envelope. The leakage characteristics are presented by a dimensionless discharge coefficient that relates the flow rate through the openings to the area of building components and the corresponding pressure difference across the openings. It is proposed to treat the discharge coefficient as a variable, which could be estimated from the blower door tests. The results of pressurization and depressurization tests carried out on the single-family house using reductive sealing method related to the different parts of the structure are presented. The uncertainties coupled to the regime of the airflow are reflected by the variation of dimensionless discharge coefficient which in terms of probability density function could be applied in the reliability models of, for example, air exchange performance of buildings.