Draft from sockets/light switches and loud ventilation system

Hello everyone,

after you gave me such great tips on telephone noise shortly after we moved into our house in the summer (many thanks to everyone for that), I have two more questions for you.

First, very briefly about the telephone noise. After much back and forth, two large silencers were installed and now the problem is largely resolved.

Draft from the sockets/switches:
We built a Kfw 40 Plus solid house with Ytong insulation - clinker or Ytong insulation - Ytong/plaster. (The general contractor called it a changeable facade)
Just yesterday, by chance while cleaning, I noticed that cold air is coming from the socket in the reveal of the kitchen window. I then checked all switches/sockets installed in the exterior walls and in all sockets the draft is clearly noticeable.
Do I have a right to have this remedied? My internet search was only half conclusive.

Loud ventilation system:

We have been annoyed by this for a while now. Installed is the heat pump Nibe F2040 with indoor unit VVM 500 ventilation system Nibe ERS 20-250CL
In the bedroom and the children's rooms, during normal operation of the ventilation system, we have about 27 decibels at the bed and directly at the ceiling outlet 45 decibels. I find it super annoying in the bedroom. I also told the site manager. He and a guy from the plumbing company just said no, it is completely normal and I would have to prove that it is outside the norm. Are there DIN standards for this? Is he allowed to simply claim based on his subjective opinion that everything is normal? He did not measure the noise.

I would appreciate an assessment from you.
Best regards,
Dodo

Draft from the sockets/switches: We built in KFW 40 Plus solid construction with Ytong insulation - clinker or Ytong insulation - Ytong/plaster. (The general contractor called it alternating facade) Just yesterday, I happened to notice while cleaning that a cold draft was coming from the socket in the reveal of the kitchen window. I then checked this on all switches/sockets installed in the exterior walls and the draft is clearly noticeable at all sockets. Do I have a right to rectification here? My internet search was only half conclusive.

Hmm, was a blower door test done?

Your ventilation system is probably just undersized and simply always running at the limit. However, I am not familiar with the device and, of course, it could also just be that it is louder than other systems due to the construction.

Hello,

Yes, a blower door test was done. It was also quite okay at about 0.6, I think.
But is the cold air coming from the sockets really okay? I also think about mold.

Can we do something with the ventilation system besides installing a bigger one? Shouldn't the contractor have known that?
According to the living space regulation, we have 165 sqm, the knee wall is 140 with finished flooring.

Is the ventilation system running constantly at your place?

Draft from the sockets is not ok. To prevent this, there are draft-tight switch boxes; those who do not use them should install the boxes into the walls with sufficient material (plaster or cement mixture) so that no drafts can occur. Kaiser offers sealing pots made of PVC. This would achieve retroactive tightness. These are inserted into the switch box afterwards. I would report this as a defect to the electrician. Regardless of what the blower test indicated.