Single-family house 150 sqm in Lower Saxony

A house of tightness: - Distance sofa - TV too tight - ok, that can be debated - standard is around 4m. 3.78m in small houses is acceptable.

That is not correct. The optimal distance to a now common 55" HD TV is between 2.20m - 3.60m. For 4k even only 1m - 2.20m. Only in the old SD format do your distances apply. However, hardly anyone will put up with that in a new building anymore... In this respect, the sofa-TV distance is still too large in the OP’s case.

I also find the living space rather too cramped, I would enlarge it and make the dining room smaller. Or rather, why even plan the wall there at all. Remove it and with it the tiny door to the hallway. Design everything open and place the TV in the lower corner.

However, having an open living/dining/cooking space is not everyone's preference. I find the separation of cooking/eating and "living" more pleasant. Let's see what the OP says about it.

That is not correct. The optimal distance to a now commonly used 55" HD TV is between 2.20m and 3.60m. For 4k, it is even only 1m to 2.20m. Only in the old SD format do your distances apply. However, hardly anyone will place themselves in a new building like that anymore... In this respect, the sofa-TV distance at the OP is still too large.

Yes, maybe I'm old-fashioned then. Who wants to watch TV at 4 people with a 1m distance? Then everyone would get a corner with their individual program zoomed into their corner? Aside from that, it's also about the general size of a common room. For 4 people, 4mx4m is quite good. Less is tight, more is better.

[...] and move the TV to the lower corner.

I always find it terrible when the TV is opposite the garden window and the sofa is oriented towards the TV. You don't always want to just watch TV on the sofa. Sometimes you also want to sit and talk, and a view of the garden is much nicer than a view of the dark wall with the dark TV. I don’t think the idea with the wall is so bad, even though I would personally prefer the "classic" separation of kitchen and dining/living room. P.S.: The villa opposite is impressive just by its dimensions!

I always find it terrible when the TV is opposite the garden window and the sofa is facing the TV. You don’t always just want to watch TV on the sofa. Sometimes you also want to sit and talk, and then a view of the garden is much nicer than a view of the dark wall with the dark TV.

I had no other intention and also suggested it. TV in the corner on the south wall. This way, looking out into the garden is always possible as well as watching TV.