Financing land and house? Taking out a mortgage? Construction costs?

I would give up the controlled residential ventilation system last. For me, the ventilation, alongside our robotic lawn mower, is a great gain in comfort because it saves valuable time. Yes, airing out takes time (and nerves!). I know that all too well from our rental apartment (also new construction).

We implemented the controlled residential ventilation system ourselves.
About €6000 in materials and an estimated 12-15 hours of work.

I would like to understand where or how you acquired your supposed expertise, Zaba12. Just because your main contractor explained one or two things to you doesn't mean those things are true or necessarily correct.

Which main contractor? There is no main contractor. But maybe every trade is cheating me, could be. I find it quite impressive in terms of saving potential that you put up the shell construction in EL. Congratulations on that.

Which system did you have installed?

Controlled residential ventilation is also the last thing I would do without. Unless you have the time to open and close all the windows several times a day for a few minutes...

Sorry, then your site manager. Buderus Logaplus Logavent HRV2... Installing it is not that far yet

Unless you have the time to open and close all the windows several times a day for a few minutes...

And then it rains for several days in a row and then there’s no airing...

In our rental apartment, airing crosswise 3 times a day for 10 minutes often wasn’t enough either. 10 minutes after airing, the humidity was back at 70%. It only got better when we heated the rooms to 22°C. However, we feel comfortable at 20.5°C in living rooms and 17°C in bedrooms. Now, with the controlled residential ventilation, it’s simply a dream, you don’t even think about room temperature, humidity, food smells, or anything like that anymore.

So I don’t find airing at all burdensome. I do it casually right after getting up and additionally as needed. Humidity is completely normal, no mustiness and no mold. When cooking and after showering, ventilation happens anyway. Even when it’s raining, ventilation occurs, except in the attic because of the skylights. I would air anyway because I find it very pleasant to thoroughly air out everything 1-2 times a day.