ᐅ Ventilation in New Construction (Central vs. Decentralized), Noise Disturbance

Hello everyone,

I am currently considering the ventilation system for our planned new build (details: Kfw 70, 2 full floors + basement + unheated attic, hipped roof, 200m² (2,150 sq ft) living space). We live in a rural area and like to keep the windows open sometimes, so we don’t necessarily have to rely entirely on mechanical ventilation.

I am torn between a central controlled mechanical ventilation system with heat recovery, a central exhaust with decentralized supply air, and decentralized supply/exhaust with heat recovery. My requirements are:
• Ventilation of bathrooms (master bathroom, children’s bathroom without windows, and guest toilet without windows) with demand-controlled ventilation based on usage
• I want to avoid having to open windows every few hours while still maintaining high indoor air quality
• Not too noisy, as I am very sensitive to noise when trying to sleep
• I am also sensitive to dry air; for example, I cannot tolerate air from air conditioning or sports halls very well

Below are the pros and cons of each system as I see them:

Central Controlled Mechanical Ventilation with Heat Recovery
+the most mature system
-expensive (I estimate about 10,000 to 13,000 Euros)
-more complex planning, including suspending and boxing in ducts
-(I heard from a provider of decentralized ventilation systems: as soon as I turn up the ventilation in the living room, more warm air is blown into the bedroom – not desirable)
-the indoor air quality in the prefabricated houses with controlled ventilation that we visited was always poor. That makes me skeptical

Central Exhaust with Decentralized Supply Air
+cheaper (maybe 2,000 to 3,000 Euros?)
+should meet minimum requirements
-energy wasted (or can I reuse the heat energy somehow? I am planning to install an air-water heat pump for heating and hot water production. Maybe the heat can be used here in a useful way). I was advised against a complete exhaust heat pump. Perhaps combined exhaust/fresh air heat pumps exist?
-cold air from decentralized supply? (I have read that with proper planning this is no problem because the supply air mixes “appropriately” with the existing indoor air)
-somewhat contradicts the idea of energy-efficient houses. Still, it’s probably more efficient than constantly having windows tilted open.

Decentralized Ventilation with Heat Recovery
+If I simply install one of these ventilators in the living-dining area, the master bathroom, and the children’s bathroom (+ exhaust in the toilet), the minimum requirements should be met. I estimate about 3,000 Euros (1,000 Euros per unit)
-if I want to cover all other rooms to avoid window ventilation entirely, it gets more expensive (maybe ~8,000 Euros) and:
-I would have many holes in the building envelope
-I hesitate to install these devices in bedrooms or children’s rooms because I think they may be too noisy.

Could you please help me with the decision? Maybe by sharing your experience or confirming or disproving some of my points? I would also like to see different ventilators in practice. Do you have any tips? I heard it might be possible somewhere in Berlin, but I live in the postal code area 5xxxx.

I look forward to your opinions.
Kiri