On the contribution of steady wind to uncertainties in building pressurisation tests

This paper analyses the contribution of a steady wind to the uncertainties in building pressurisation tests, using the approach developed in another paper (Carrié and Leprince, 2016). The uncertainty due to wind is compared to the uncertainties due to other sources of uncertainty (bias, precision and deviation of flow exponent).
The main results of this study are:

• The model error due to the wind on the estimated airflow rate is relatively small at the high pressure point (12% at 10 m/s), but it can become very significant at the low pressure point (60% at 10 m/s);
• At the high pressure point, the uncertainty due to wind remains smaller than that due to other sources of uncertainties up to 6 m/s, whereas when a two-point pressurisation test is performed to calculate flowrate at 4 Pa, the impact of wind may become dominant at 4 m/s;
• Having a constraint either on the zero-flow pressure or on wind speed seems effective to control uncertainty (provided these quantities can be adequately measured);
•  Averaging results between pressurisation and depressurisation is mostly beneficial at intermediate wind speed (around 4 m/s) when a reference pressure of 4 Pa is used;
• The uncertainty due to steady wind is mostly critical for single-sided dwellings or zones tested alone;
•  For single-sided dwellings or zones, to estimate flowrate at 4 Pa, it is better to perform:
• up to 5 m/s, a 2-point test and extrapolate with a calculated flow exponent;
• above 5 m/s, a test at 50 Pa and extrapolate with a default flow exponent.