Purpose of the work
This work presents multiple in-situ measurements of building components airtightness using a direct component testing. Its purpose is to highlight advantages, drawbacks and limitations of the method compared to other methods for measuring in-situ the airtightness of building components (e.g. the indirect method).
Method of approach
These objectives were obtained by observation of in-situ tests performed on different newly- installed windows and by statistical analysis of repeated tests. The uncertainty of the method was compared to theoretical calculations of uncertainties for other methods.
Content of the contribution
This contribution is made of three parts. Firstly, the in-situ measurement using direct component testing has been described, as such as the required equipment. Secondly, the measurement method has been applied to three different cases of windows: one loose pressure chamber and two fixed pressure chambers. The observation of these three cases highlights some limitations and attention points of the direct component testing method. Thirdly, a series of 10 repeated tests has been performed in order to have an indicator of the method accuracy. Lastly, the uncertainty of the most commonly used method has been computed for a theoretical case in order to compare with the accuracy of the direct component testing. The most commonly used method is the indirect method and it consists in successive blowerdoor with sealing of the component of interest between two tests.
Results and assessment of their significance
The three tests performed on newly installed windows (flows through the window frame and the window-wall interface) provide air flow at 50 Pa of 5.12, 28.41 and 4.63 m³/(h.m²) for cases 1, 2 and 3 respectively. These tests highlight two particular attention points. Firstly, if the pressure chamber is loose, one has to maintain low pressure differences in order to avoid damages in the pressure chamber (case 1). Secondly, it is important to sealed all the undesirable air leakages before testing in order to avoid measuring irrelevant airflows (case 2).
The repeated tests show that the pressure chamber was damaged due to the successive pressurization/depressurization cycles, leading to an increase of the air leakages. A series of 10 tests has been performed, and the pressure chamber has been re-build between the 6th and the 7th test. The standard deviation of the results is 0.99 m³/h (10.2% of the air flow) for the first part (1-6) and 0.28 m³/h (4.2 % of the airflow) for the second part (7-10) of the repeated test.
These values can be used as indicator of the method accuracy, but not as a value of its uncertainty because of the increasing airflow. For a theoretical case similar to the repeated test, computation with favorable hypotheses leads to an uncertainty of 1.02 m³/h.
This study shows that direct component testing has a strong potential to measure airtightness at building component scale, especially regarding its reliability. However, the tests performed highlight some specific point of attentions. Further work should focus on the application of the method on other building components and on the rigorous quantification of the method uncertainties.
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