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Purpose of the work
To measure airtightness, large buildings (multi-family dwellings) require more time, personnel, and equipment than small buildings (single-family dwellings). However, this outlay is not due to stricter requirements relating to the envelope surface of larger buildings, but to the more complex structure (access, supply). Exterior envelope surfaces and interior joint faces make specific contributions to air permeability, depending on the selected design, location in the building, and conditions for the measuring task. The aims of this paper are to add to the knowledge about leaks inside large buildings, to clarify whether specific patterns or accumulations of air leakage rates are repeated in different buildings and, finally, to answer the following question: When airtightness measurements are performed according to specifications in national annexes NA and NB to DIN EN ISO 9972:2018-12 regarding sampling for measurement of individual apartments, how much can the results of airtightness measurements deviate from the results of a complete measurement of large buildings?
Method of approach
In buildings where the apartments have a central access point, the applicable requirements can be tested using a single measurement. In multi-family dwellings with separate access points, the requirements can be tested using sequential measurements of individual apartments.
However, this exploits only some of the information that is potentially available. Ten multi-family dwellings were tested both individually and with pressure regulation using specialized software (TECLOG) and multiple fans. Taking into account normative limit values for the air permeability of components and joints between components, a comparison can be made to determine the percentage of internal and external air leakage rates for each apartment and for the entire building.
Content of the contribution
Over the past few years, a collaborative effort between Jade University of Applied Sciences in Oldenburg, FLiB, BlowerDoor GmbH, EB Holtgrave, Osnabrück, and other measurement service providers made it possible to take comprehensive and extremely detailed measurements of a number of large buildings of different designs. The results are used to draw conclusions about the processes behind leak distribution, about the percentage of internal and external leaks, and about the validity of the measured values.
Results and assessment of their significance
Complete datasets are available for many buildings, making it possible to compare the characteristics of the entire set and those of all possible samples, limited by specifications in the national annex. Based on the comparison, conclusions are drawn about the distribution of characteristics and about the reliability of the assessment of measured values, which is of tremendous importance when it comes to the practical task of measuring the individual building.
Conclusions
Airtightness specifications in Germany currently relate only to the heat-transferring area of a building’s external envelope. Specifications for airtightness between fire sections/apartments refer only to quality. In addition to statements about the reliability of results that are influenced by statistical, systematic, and other error values, practical aspects of the fitness for purpose of multi-family dwellings play a special role in this investigation. This discussion of fire, noise, odor, and pest protection has only just begun.
Note
For more information, please contact the reference author at: Andreas.Kaschuba-Holtgrave@t-online.de