160m2 detached house in timber frame construction on the north slope with basement

We have filters in front to prevent the pipes from getting dirty. The contamination problem should now be resolved. You can also ventilate at any time with a [Kontrollierte-Wohnraumlüftung]. Anything else would be a nightmare. The ventilation you like should be installed by Nordlys. It’s best if you ask around. Neighbors, colleagues, sports clubs, etc. Who they built with and what experiences they have. I could simply imagine that a [Stein auf Stein GU] builds you an [Energieeinsparverordnung] house – not a stripped-down [KFW 55] – and they have no problem using the basement as living space. Timber frame builders simply build their standard 08/15 house on top or get the idea to place the house 1 meter in front of the retaining wall (this was suggested to us). You should build so that as little excavation as possible is needed.

No one can seriously tell me that those things can be cleaned.

It would certainly be funny to see if there is a statistic on what market share controlled residential ventilation has among builders who work as bar cleaning technicians.

An architect we spoke with recommended window slot ventilators as intake + decentralized exhaust through the bathrooms/kitchen

You are building a new house where as little uncontrolled ventilation loss as possible should occur. Therefore, a "blower door test" is even carried out to detect leaks and windows with three sealing levels are installed.

And then you put a slot in the window frame/seal so that you have more uncontrolled air exchange without heat recovery?

In addition, window rebate ventilators only serve to ensure the air exchange necessary for moisture protection if it is not present. In normal use, that is when someone is at home, ventilation is still necessary.

So you have a guarantee of the usually existing minimum air exchange anyway and additionally uncontrolled heat losses and the risk of drafts. Great devices.

If you do not like a central ventilation system but definitely want ventilation, just take decentralized systems with heat recovery. One in the living/dining area, one in the bathroom, and one each in the bedrooms and children's rooms.

So far, everyone has told me that the heat recovery is not worth it. I understand the argument that window slot ventilators create holes in the dense wall, but I don’t find it very relevant. With that reasoning, you wouldn’t be allowed to ventilate anymore. Filters in a controlled residential ventilation system may help against larger particles, but they certainly do not prevent biofilms from forming due to various bacteria... I don’t want that. The pipes are also fixed in place and cannot be replaced anymore.

At the moment, we are considering changing everything fundamentally by moving the children's rooms and children's bathroom to the basement, redesigning the ground floor layout, and building no knee wall and a steep gable roof in the attic for the parents’ area.

Before you consider decentralized controlled residential ventilation systems, visit a house with these devices. Depending on the location of the house, this is not suitable for every property. The devices are quite audible, and even more critical is the outdoor noise that can be carried into the house. If you are located deep in the new development area (=quiet) and are not too sensitive, the technology is a good and relatively inexpensive alternative to centralized controlled residential ventilation.

Window rebate is not the drama it is always portrayed to be. You just have to keep in mind that you then ventilate once in the morning and evening accordingly. The heat losses are limited. However, please keep in mind that there is a difference between an apartment from the 80s and the airtight new building; in the apartment, you can ventilate, in the new building, you must. The air becomes unpleasantly stuffy.

At the moment we are considering changing everything fundamentally by putting the children's rooms and children's bathroom in the basement,

But that's not nice towards the children, to put them in the north and by the street.