Large Buildings Airtightness Measurements using Ventilation Systems

Abstract

Due to high cost and limitations in availability of specialized and expensive measurement equipment, airtightnes testing of large buildings is relatively uncommon. Sometimes, in existing buildings, leakage measurements can be conducted with the use of ventilation systems, which is allowed by some standards. For this kind of test one can use the measurement of the airflow rate at fans (fan inlet nozzles), at variable air volume terminals (VAV) or in the duct system. The accuracy of the airflow measurement is crucial in these cases.Attention should be paid to a number of aspects related to building preparation and test procedure. The problems of large building 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-up.In the case of multi-zone airtightness measurements, the ventilation system can generate an appropriate pressure in adjacent zones. Another application is the coarse testing of 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 a ventilation system, the biggest problem is reliable measurement of the airflow rate with the accuracy required by the standards. To obtain accurate results much more expertise and effort are required than in the case of measurement with a set of typical blower door fans.