decentralized ventilation - various manufacturers

I'll throw Seventilation (we have it ourselves) and Halmburger into the ring. Household electricity (including ventilation) has been ~€32 per month since February. Air quality is good. Acoustics are okay... though I would prefer it quieter. I would recommend listening live here.

We have 8 Marley fans. Costs including installation around €5,000. The noise is not insignificant, I have to turn off the fan in the bedroom at night.

Hello "Passivhaus", it is known that Marley performs worse in terms of noise levels. Ventilation is especially important in the bedroom, as the worst air quality occurs here. Perhaps you should look for a good alternative. (Einzelraumlüftungsgerät)

Do you have any recommendations for good alternatives?

Hello Jochi79,
for retrofitting, especially in the bedroom, the ROOS Air Mini 60 is very suitable, for example. Very quiet device and easy to install, as the control is in the device. Excellent air performance with very quiet operation. You only need a power outlet and 2 drill holes DN 110 mm.
In the decentralized area, we have had the best experiences with the Sevi 160 plus. Greetings from Bernau

The responsible ventilation planner recommended the Dimplex DL 50 WE to me, are there possibly any experiences with it?

My favorite would actually be the Meltem since there is a KNX-compatible version, what are the opinions here?

Greetings from the south