KfW 55 - Ventilation system yes/no? - Experiences

Without a ventilation system, it is already not permitted under the Building Energy Act (Energy Saving Ordinance) with an increased energy saving standard. This also applies to the KfW, which bases its regulations on the Energy Saving Ordinance or later the Building Energy Act. First, you need the space associated with costs (excluding fire protection), then the ducts must be maintained. The energy expenditure can be up to 15 times higher due to system losses alone. The efficiency of the heat exchangers in all good devices is now well above the standard values. A disadvantage of decentralized devices is that they are visible on the facade.

Without a ventilation system, it is already not allowed according to the Building Energy Act (Energy Saving Ordinance) with an increased energy saving standard.
This also applies to the KfW, which bases its regulations on the Energy Saving Ordinance or later on the Building Energy Act.
First of all, you need the space, which is associated with costs (fire protection aside), then the ducts have to be maintained.
The energy consumption can be up to 15 times higher due to system losses.
The efficiency of the heat exchangers in all good devices is now well above the standard values.

The disadvantage of decentralized devices is that they are visible on the facade.

Sorry, that is simply not true. What system losses? The ducts are generally maintenance-free or can be cleaned yourself every 10 years with some systems (if desired). Decentralized systems are junk and are still often installed in multi-family houses by developers. Cheap and no central filter management necessary.

First of all, you need the space associated with costs (fire protection excluded), then the lines have to be maintained. The energy expenditure can be up to 15 times higher due to system losses.

But you do know that we are talking about a single-family house, right? From a fire protection point of view, the entire single-family house is considered as one area (an exception could be a masonry garage directly attached to the house, but I’m not 100% sure about that). The lines also do not have to be maintained; in VDI 6022 it is recommended, just like in any other DIN standard, but it is not a law. If the lines, for example, lie in the cold attic and are not sufficiently insulated, it can lead to increased losses; however, with properly executed insulation, it is absolutely negligible.

Exception could be a masonry garage directly attached to the house

Hardly anyone would do that nowadays, solely because of the equivalence proof for thermal bridges.
An individual proof becomes far too expensive, as even a single-family house quickly accumulates 50 details, each costing at least €150 per detail.

Of course, a masonry garage attached to the house is possible. Even with a passive house. What thermal bridge? The wall between the house and the garage is insulated just like the other freestanding walls.

A central ventilation system is not completely noiseless. I hear ours at night when everything is quiet. Regulate the air exchange downwards and it should also be tolerable for your fiancée.
In our case, every air outlet is separately ducted, no noise transmission.
I wouldn’t choose a decentralized ventilation system if you are sensitive to noise. There are always threads on the topic of sound transmission in connection with decentralized systems.
I don’t feel any drafts. I have to stand right at the air outlet—without shoes.

Whether necessary or not, I find controlled residential ventilation pleasant. Ventilate when you want, not when you have to.

Ok he probably finds it funny to make fools of us, after his last post all clear. I'm out of here :)