ᐅ Is a ventilation system now mandatory for new buildings under the 2016 Energy Saving Ordinance?

Hello Forum,

I am new here and hope you can help.
It’s about our new build project, which is scheduled to start in April.
The goal is to build a KfW 55 house (solid construction). We originally planned to do this without a ventilation system.
However, we keep reading here and there that a ventilation system is mandatory for the KfW 55 certification.
Additionally, today the local utility company informed me that the 2016 Energy Saving Ordinance requires automatic ventilation. The builder, on the other hand, insists it is not necessarily required.
Can you help clarify this?
1. Is it really mandatory?
2. Can you manage well without it, or is it better to invest the money in a ventilation system?

I look forward to your advice.

Thank you very much.

The 2016 energy saving regulation does not require a ventilation system.

Are you sure you want to build without a ventilation system?

And for pure comfort, RuleAir in the windows is sufficient.

I was actually sure that I wanted to build without a mechanical ventilation system with heat recovery. Unfortunately, doubts are gradually arising.

What is the reason you want to build without a mechanical ventilation system with heat recovery? Cost?