airtightness test

Worldwide, the demand for airtightness tests of tall buildings with a height of approximately 100 m is increasing. This report provides information on the planning and measurement concept for testing the entire building as a “single-zone” and presents the results and findings of the airtightness tests. The test set-up and the tests as such are based on the Passive House Institute's Guide to Measuring Tall Buildings [5] which includes recommendations that go beyond the ISO 9972 standard.

The information about uncertainly is essential to correct interpretation of any measurement. Therefore, several authors investigated the reproducibility and repeatability of airtightness measurement during the last years. The experiments were carried out in real buildings of different size and in actual climatic conditions which complicates the comparison of results. Namely, the question whether the uncertainly is proportional to the measured air flow rate remained unanswered.

The trend in European countries, such as Belgium, France and Germany is that the quality of the airtightness of the building envelope is getting better and better. This is true for small, airtight apartments, Passive houses and some large buildings with an excellent airtightness due to special requirements, e.g. oxygen reduction or fire protection.

Building airtightness tests have become very common in several countries, either to comply with minimum requirements of regulations or programs, or to justify input values in calculation methods. This raises increasing concerns for the reliability of those tests. Despite the extensive debates about how the building pressurization test standard ISO 9972 should address sources of uncertainties, no change has been implemented. According to the current standard, the zero-flow pressure shall not exceed 5 Pa for the test to be valid.