ᐅ Centralized or decentralized ventilation system

Hello everyone,
Maybe you can help me.

We have a small apartment of about 35 to 40 square meters (375 to 430 square feet) with one bathroom, one master bedroom, one living area, and one storage room.
From around mid-October to about April, there is recurring unpleasant musty basement-like odor in the apartment.
The apartment is not used daily, so ventilation is irregular.
There is no mold or anything similar present.
I have been thinking about either a decentralized or centralized ventilation system. I understand that with a centralized system all rooms would be ventilated.

Would this solve the problem, and are there ventilation systems available that fit this size? So far, I have only found larger units. Or is it possible to adjust them down to a size that would be suitable?

1. Apartment = rented or owned
2. If owned, then the question is whether it is a condominium within a homeowners association or if you own the entire building
3. With the apartment size, a central system will be practically impossible to install. You need a central unit and the corresponding ductwork.
4. Decentralized = core drilling through the exterior wall and installing the unit or connecting it to the power supply (often it can even be plugged into a standard outlet)
5. No daily use = no daily ventilation. Is the space at least heated properly every day? Otherwise, the musty smell could already be developing into mold

Stefan1510 schrieb:

Would this solve the problem

It at least ensures continuously fresh air. The system will not help against a musty smell if mold is already developing (for example, if there is insufficient heating).

Stefan1510 schrieb:

Are there ventilation systems available in the size that would fit?

There are plenty of suppliers for decentralized systems.

The entire house is owned.
It is already heated, and there is no mold growth.
Piping for a central ventilation system would not be a problem due to the room layout.
My concern with a decentralized ventilation system is that not all rooms would be properly ventilated.

Stefan1510 schrieb:

Heating is already installed

What temperature do you maintain inside the rooms?

Stefan1510 schrieb:

Piping for a central ventilation system wouldn’t be a problem due to the room layout

How do you plan to do that? Suspended ceiling? Bulkheads over the rooms above or below the apartment? Where will the supply and exhaust air be located? Where will you place the central unit?

Stefan1510 schrieb:

My concern with decentralized ventilation is that not all rooms would be ventilated

If you can’t install a device in every room and the doors are usually closed, then no.

Alternative: An exhaust fan combined with trickle vents in the window frames.

Central is – trust me – a foolish idea.

When no one is home, the temperature in the rooms is always set to 19°C (66°F). Installing cladding wouldn’t be a problem; it would only need to cover 3 meters (10 feet) in the bedroom, which will be repainted soon anyway. Everything else can be installed in the adjacent basement room. I have attached a sketch of what I had in mind. In my opinion, a decentralized ventilation system would be more complicated here because I would need to ventilate every room and would have to make at least four core drillings.

nordanney schrieb:

If you can’t install a unit in every room and they are all initially closed off, then no.

I don’t quite understand this.
Attached is the sketch.