Building pressurization tests in a wind tunnel: design and characterization of a reduced scale experiment facility

Purpose of the work
This study is a part of a thesis work that aims to evaluate the error induced by the wind during building pressurization tests performed according to the ISO 9972 method on a reduced model in controlled laboratory conditions.
Method of approach
In order to reproduce pressurization test, we have design and characterize a new experimental facility that includes a model reproducing a single-zone building, a pressurization device that replaces a blower door, and a wind tunnel that reproduces steady wind conditions. The design phase was performed according to similarity conditions that ensure that the experimental results on the reduced scale will be consistent with physics that occurs on a full scale.
Content of the contribution
The contribution include a detailed presentation of:

1. the 1/25th model which is scalable and provides nine configurations of leakage distribution between windward and leeward façades, with the same averaged total airtightness for all configurations.
2. our pressurizaiton device that includes a flow controller, a compressor and a manometer, and that automatically reproduces pressurization tests thanks to Labview applications called by a VBA program we have developed ;
3. a 4.11 m wind tunnel that includes a 1.5*1.0*1.0 m³ testing chamber, providing steady wind from less that 1 m s^-1 to 7.5 m s^-1.

Results and assessment of their significance
First, the averaged total airtightness of our model is q4=0.17 m3 h-1 for all the 9 leakage distribution configurations. The airflow through each leak has been characterized and corresponds to turbulent airflows (n=0.5). The model includes movable façades and openings: the model can be developed to include more openings and openings with different shapes and materials. The values of the pressure coefficient evaluated on the windward and leeward façade correspond to the orders of magnitude given in the literature.
Secondly, the pressurization device provides stable pressure difference to our model, from 10 to 100 Pa, for all leakage distributions with wind speed up to 7 m s-1. Finally, the wind speed inside the testing chamber is homogeneous and can be stabilized from less than 1 m s-1 to 7.5 m s-1. The wind velocity inside the testing chamber are very stable in time and stable in space.
Conclusions
Therefore, we can reproduce pressurization tests according to ISO 9972 using our experiment facility, including pressure sequences from 10 to 100 Pa for different steady wind conditions and with 9 leakage distributions.

For further information please contact Adeline Mélois at: adeline.melois@cerema.fr