New Energy Saving Regulation 2009 Blower-Door Tests

For the measurement procedure itself and the limit values, nothing has changed in the Energy Saving Ordinance 2009 compared to the previous regulations.

According to DIN V 18599-2 Table 4, buildings are classified into categories I-IV depending on their airtightness.

The reference building to be used for comparison purposes within the framework of the Energy Saving Ordinance calculation is indeed oriented towards category I, but category II could probably be applied to the building to be calculated if the Qp limit value is mathematically (also without blower door measurement) undercut.

Since the EP mentions "notwenig," I had rather suspected legal aspects. So whether, for example, a "final decision" has not yet been made and thus the builder still has the option to choose. Therefore, for me, §28(1) or §28(4) would first be relevant. If it was approved according to the Energy Saving Ordinance 2007, then the Energy Saving Ordinance 2009 might not be fulfilled at all. If the Energy Saving Ordinance 2009 is the basis, then the situation is clear. Best regards

Since "necessary" is mentioned in the EP, I had rather suspected legal aspects.

"Legally," there has (unfortunately!) never been an obligation to carry out an airtightness test.
However, such a "necessity" has always arisen since the Energy Saving Ordinance 2002 whenever the possible bonus for it was claimed in the Energy Saving Ordinance certificate.
Even if the building has a mechanically operated ventilation system, a differential pressure-assisted leak detection is strongly recommended to ensure comprehensive ventilation of the building.
Even if all the assumptions made above were incorrect, I could very well understand the wording "necessary blower door tests" insofar as the client considers this quality check to be sensible and necessary. If applicable, this "necessity" may also arise from the agreements of the concluded construction contract, in which the construction target regarding airtightness requirements was also mandatorily formulated ... which, by the way, I can only recommend in any case! :)

@KPS
that is probably why the words necessity and duty have different meanings. ;)