Blower Door Test - Meaning of the Result

Hello,

today we had the airtightness test as the last trade in the already occupied house.

The result: N 50 = 0.68

We built solid Kfw 70 (2017). What does that mean? Is that good, okay, or rather so-so?

Is it to be expected that there are particularly harmful leaks? The tester found a slight leak at a sliding door but considered it within limits, which brings us back to the original question

Depending on the source, different limit values can be found. The Energy Saving Ordinance states 3.0 and with a ventilation system 1.5. KFW states 1.5 in program 153 at funding level 40 Plus also with (mandatory) ventilation system, but recommends <0.6. A passive house should also be <0.6 according to PHPP. I do not know regularly usual measured values for comparable new buildings. In this case, I would trust the person measuring that your value is okay. Is the sliding lift door leaky at the connection? Otherwise, this could still be mentioned to the supplier. Besides, sliding lift doors are simply inherently not perfect when it comes to tightness (also in regard to water).

0.6 is the minimum requirement for passive houses - so your value is really good.

We had 2.5 in the first measurement. There were two unsealed openings: 180 mm chimney draft, 180 mm exhaust air in the kitchen. So 3.0 would really be shoddy work if that is the final state after the Energy Saving Ordinance.

I would assess leaks depending on their location. A leaky door to the cold attic is "deadly." Poor vapor barriers that can lead to condensation in the insulation layer I would tear out. A leaky terrace door, on the other hand, would almost be acceptable to me.

We had a value of 0.511

So 3.0 would really be botched if that is the final state according to the Energy Saving Ordinance.

Yeah, I think so too. But it really is like that, you can check it yourself. In general, the Energy Saving Ordinance and the EEWärmG are by far not as bad as their reputation suggests. There are numerous exceptions, substitute measures, generally "many roads lead to Rome". You can also apply for exemptions if the economic feasibility is not given, etc.