New construction KFW 70 house and your opinion on our project

May I ask why?

Hello,

a controlled residential ventilation system is, in my opinion, more than just a comfort feature with today's construction methods.

Buildings today are constructed so tightly and insulated that there is a latent risk of mold formation if ventilation is insufficient.

According to manufacturer guidelines, someone should basically always be home to ventilate properly.

Apart from that, with a controlled residential ventilation system with [WRG], I also don’t let the expensive heat go out the window.

We were initially skeptical as well – but by now we wouldn’t want to be without our controlled residential ventilation system.

Regards,

Dirk

I might have better written, with which measures do I achieve the best P/L ratio.

Doesn't the idea contradict itself with the construction of a bungalow of over 240 sqm? Or what did I read there?
With a 2-story building (to put it loosely) you would have less external surface area and very probably better values – at least that's how I understood it as a layperson.
...

Actually, houses today should be insulated so well that mold can no longer be a problem! Unless you have thermal bridges or let the window reveal cool down through tilt windows - and then mold mixes with comfort. If you don't do that, it is extremely musty and unpleasant.

I believe you both have a point:

You know that your argumentation is twisted?
Precisely because it is so well insulated, the risk of mold formation is high.

Then houses in the past shouldn’t have had mold. But they did, and not just rarely. Besides thermal bridges, rising damp is often the problem there.
The moisture must get out of the house, whether it’s a new or old building.

but from the transpiration of our bodies (several liters per night, how much exactly I have to guess),

Several liters sounds good to me, then I would be a few kilos lighter every morning. Sleep diet.
Just guessing, I’d say about 500ml or 0.5kg when I compare the scale in the evening and in the morning.

So with heating air, unventilated rooms are prone to mold.

It is true that mold forms where there is moisture.
The problem is not the heating air itself, but when there are large temperature differences.
If you leave a room unheated but the doors are open, mold will appear in the unheated room.
Warm, moist air from other rooms cools down in that room and cannot hold the moisture, which then settles on windows, walls, etc. and that is exactly where the mold forms.
We had this problem a lot in our last apartment. The cat also had its territory in the study. Because of that, the door was always open. Mold problems appeared when unheated. If you slightly turned the heating on, it got better.

In summer a similar situation but without heating:
Warm, moist air outside. Nice cool temperature inside the apartment due to thick natural stone walls. Tilting the windows then led to mold on the walls.

At least we have managed well in our solid house without controlled residential ventilation. Twice a day proper airing and so far no mold.
Controlled residential ventilation buys you some free time. Whether the 20 minutes daily for opening and closing windows 2-3 times is worth it is something everyone has to decide for themselves. The same goes for other helpers starting from everyday appliances like dishwashers and washing machines to automatic vacuum cleaners, automatic lawn mowers and automatic irrigation systems.

Yvonne, you are of course right – for growth it doesn't have to be "cool" but at least 10° – but for the water to condense from the air on the wall/window, it has to be cooler than the air temperature in places.