The airtightness test of the building is one of a few building envelope measurements used in practice, which is quantitative, not just qualitative as e.g. infrared thermography. The so-called blower-door test result may be a measure of the building design and construction quality and could also be used for the energy demand for heating and cooling analyses.
With the development of energy-efficient buildings, the awareness of the airtightness importance increases, which results in a growing number of measurements of small and mid-size structures. Due to the high cost and limitations in availability of measurement equipment, tests of large buildings are relatively uncommon. Sometimes in the existing buildings the leakage measurements could be conducted with the use of ventilation systems, which is allowed by the (EN 13829) standard. For this kind of tests one can use the measurement of the air flow rate at fans (fan nozzles), at variable air volume terminals (VAV) or in the duct system. The accuracy of the air flow measurement is crucial in these cases.
Attention should be paid to a number of aspects related to the building preparation and the test procedure. The problems of large buildings leakage tests are discussed in this paper, as well as typical design and workmanship mistakes. This paper presents the methodology and results of airtightness measurements of the selected facilities envelopes using a ventilation system in comparison to blower-door set.
In the case of multi-zone airtightness measurements, the ventilation system is suitable to generate an appropriate pressure in the adjacent zones. Another application is the coarse testing of the airtightness of the building, when the result of the measurement can be approximate. In the case of final measurement of the airtightness of the building with the use of ventilation system, the biggest problem is the reliable measurement of the air flow rate with the accuracy required by the standards. Measurement of airtightness of large buildings with use of existing ventilation system can be completed correctly in some cases, however, to obtain accurate results more expertise and effort are required than in the case of measurement with a set of typical blower-door fans.