Theo Reuter
Bibliographic info:
10th International BUILDAIR Symposium, March 31/ April 1, 2017, Hannover, Germany

Purpose of the work

Many ventilation systems do not work efficiently, because their airflow rates have not been correctly adjusted and due to leakages of the ventilation ducts and individual elements.

Method of approach

Different measuring devices are used to evaluate and adjust the flow rates, to conduct airtightness tests with differential pressure measurements of ventilation systems or their parts, as well as to search for leakages of ventilation components.

Content of the contribution

For expert reports and opinions, numerous inspections of central ventilation systems regarding flow rates and above all the airtightness of ducts have been conducted in commercial as well as residential buildings. This presentation will show possible measuring procedures, experience, and deficiencies.

Results and the assessment of their significance

Among other things, it has been determined that in more than 90% of all single-family houses and apartment buildings, the flow rates had not been calibrated / adjusted as they should have, if you consider the planning documents / the ventilation design according to German Industrial Standard DIN 1946-6. This was frequently caused by insufficient measuring devices and a lack of knowledge. In some cases, damage from condensation and mold growth could be traced back to wrongly-adjusted air flows. During many evaluations, it was also discovered that ventilation systems had not been set-up in the thermal building envelope and air ducts had not been insulated. In addition, sometimes even considerable air leakages were detected in air ducts. In most cases of large systems (e.g. in hotels and offices), the air ducts did not even meet the airtightness standard according to Eurovent 2/2 - airtightness class B. The resulting energy losses are sometimes significant.


Planners of technical building services, energy consultants, and architects should focus more strongly on the correct installation and adjustment of the ventilation systems and point out the corresponding measurements and measuring procedures, as well as the measuring devices to be used, already in the offer. It also frequently shows that the respective airtightness measurements during construction are highly recommended. Measuring the airflow rates and the airtightness of ducts with differential pressure devices has proven to be very effective. Energy losses caused by leaky ventilation ducts and wrongly-set airflow rates are apparently a factor that is frequently underestimated.


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