Decentralized ventilation system with 24V?

Yes, I only have one exterior wall in the bathroom. And since there is, of course, a 1.13 meter wide window in the exterior wall and the bathroom in total is only 7.65 sqm with bathtub, shower, sink, and toilet, there is simply no space left.

Hopefully your planner has taken this into account when sizing the heating surfaces! In addition, a clear distinction should urgently be made between Be and ventilation systems in general! You probably mean a pure exhaust air system in the bathrooms without heat recovery? In this case, a room-specific negative pressure is created, which must be balanced by supply air in any form. If there is a wood stove in the building, this can become critical assuming an "air connection," especially with RLA! In the worst case, this increases infiltration of outdoor air into the building, which one actually wants to limit in new buildings due to airtightness requirements! In addition, the air exchange rate will decrease degressively with the running time, which is probably not intended. That would be counterproductive! Alternatively, a decentralized supply and exhaust ventilation with heat recovery would be interesting! Variant 1! Best regards.

I do want a decentralized ventilation system with heat recovery. Everything else makes no sense in my opinion. And out of 6 different offers, only one mentioned something about compensation through a wall heating system.

I definitely want a decentralized ventilation system with heat recovery. Everything else makes no sense in my eyes. And of 6 different offers, only one mentioned compensation through a wall heating system.

Have fun with your project, as it is neither effective nor economically sensible overall. ;-) Possibly, giving up might be more economically valuable overall! ;-) "Half-pregnant" rarely ends well! ;-)

best regards