Purpose of the work
A procedure for the preparation of buildings for airtightness checks in compliance with legal requirements was to be defined in a standard. It should be possible to transfer the measurement result directly into the energy performance calculation as specified in DIN V 18599 without making any mathematical corrections. Checklists in the standard should largely eliminate the need to consult previous publications on interpretation issues.
Method of approach
The Federal Office for Building and Regional Planning (BBR), the Federal Office of Economics and Export Control (BAFA) and the Fachverband Luftdichtheit im Bauwesen e.V. (Airtightness in Building and Construction Association) (FLiB) were closely involved in the standardization work.
Content of the contribution
The German national annex precisely specifies the requirements regarding the time of measurement: The airtight envelope including all penetrations must have been completed.
With respect to building preparation, (national) procedure 3 is defined, in which intentionally existing openings are prepared in such a way that the measurement result can be transferred to the infiltration calculation according to DIN V 18599. The preparation of the various building elements and openings is set out in three tables, similar to the checklists of the FLiB. Furthermore, it is specified that tests under depressurization and pressurization conditions must always be carried out.
Since the "internal volume" in the main section of ISO 9972 is defined differently than in EN 13829 and in DIN V 18599-2, the national annex defines the "air volume" as a new reference value which corresponds to the internal volume of the previous standard EN 13829. Other terms and symbols, too, differ between ISO 9972 and EN 13829.
For large buildings and those in which no airflow connections can be established, the standard describes various variants of measurements taken section by section with and without pressure regulation in adjoining sections. Important to know: Measurements taken with pressure regulation in adjoining sections are therefore expressly permitted as an option, but are not mandatory as such.
For conducting measurements at, for instance, multi-occupancy buildings with access via outdoor balconies, the German national annex provides for taking random measurements and describes how the air permeability of the entire building is calculated on the basis of these.
Results and assessment of their significance
Measurement service providers and other participants will have to adopt the amended terms and symbols defined in particular in the main section of ISO 9972. In some cases, building preparation becomes easier and calculation is facilitated: For example, compared to procedure B of EN 13829, temporary sealing of the lift shaft ventilation, which is often difficult due to poor accessibility, is no longer necessary. The requirement to measure at both negative and positive pressure is practical because the result is more accurate and certain errors in building preparation are more likely to be detected.
The German national annex achieves the above-mentioned aim of harmonizing DIN V 18599-2 and DIN EN ISO 9972. As a result, the measurement outcome can be used as an input to the energy performance calculation and serves for more than just answering the question of "passed" or "failed".
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