Interlaboratory tests for the determination of repeatability and reproducibility of buildings airtightness measurements

The issue of the uncertainty of building airtightness measurements has built up a greater importance since this topic was introduced in many regulations regarding the energy performance of buildings. Different studies have contributed to the evaluation of the uncertainty but the question is still incompletely solved in practice.
To contribute to the determination of the repeatability and reproducibility of these measurements in practice, the Belgian Building Research Institute organized interlaboratory tests with 10 other laboratories.
This paper presents the details of the study together with the repeatability and reproducibility standard deviation calculated at different pressure differences. The issue of unweighted vs. weighted least square regression is also discussed.
The reproducibility standard deviation calculated at 50 Pa was 2.4%. It was below 3% between 30 and 100 Pa but was noticeably higher at 4 and 10 Pa. However the application of a weighted least square regression showed a possibility to reduce the standard deviation of the results calculated at low pressure difference