Pedro F. Pereira, Ricardo M. S. F. Almeida, Nuno M. M. Ramos, Rui Sousa
Bibliographic info:
35th AIVC Conference " Ventilation and airtightness in transforming the building stock to high performance", Poznań, Poland, 24-25 September 2014

When one intends to evaluate buildings energy efficiency their airtightness is a fundamental parameter. Airtightness is linked to undesirable and uncontrolled ventilation and, therefore, should be minimized. Quantitative characterization of expected leaks of common building elements would be useful for practitioners that intend to improve building enclosures for airtightness optimization. The most well accepted experimental procedure to evaluate in-situ buildings’ airtightness is the fan pressurization method, typically making use of a “blower door” device. Individual components can be tested for air permeability in laboratory conditions according to well established standards. A systematic approach for components contribution to overall airtightness is lacking, especially due to insufficient measured data availability.

The paper presents a case study where in-situ blower door measurements were used to define the contribution of different building components to the airtightness of a small building. Several set-ups were established allowing for the individual effect of the components to be measured, namely: enclosure, windows, connection of the steel columns with the floor and ventilation ridge. An enclosure sample, including wall panel and one window, was built in the laboratory and air permeability tests were performed. The information from both in-situ and laboratory tests was combined in a methodology for airtightness prevision of a small building. The laboratory results, completed with air leakage values obtained from a published database, provide the base value for airtightness computation. That first value is then corrected and/or validated by the in-situ measurements of individual components.

Results indicate that the application of the methodology for Mediterranean countries, with the construction elements air leakage database available, could be questionable. A very different construction reality from the one in the countries that contribute for the database was found. The importance of a large number of studies in the Mediterranean countries, where constructions are less airtight, arises and should be the basis for a new database.