Healthy Building - What is important?

This is a concept from the 1920s when windows were still built and installed in such a way that they were drafty. And in fact, you didn’t need to open windows anymore.

The concept is more relevant than ever and suitable for all those who want to critically question whether a house designed like a plastic bag is truly bliss.

I can still imagine that some building materials can temporarily absorb a bit of moisture and then release it again, but I would also be interested in how the materials really differ there (numerically).
So how much better is clay plaster? 1%, 10%, 100%?

How much better clay plaster is cannot be said in general terms.
First of all, the question is better asked: better in which property and better compared to which reference building material.
Clay has a thermal conductivity of 0.91 W/mK, a temperature diffusion coefficient of 19 m²/h, a vapor diffusion resistance of 8, a heat storage capacity of 600, a heat penetration coefficient of 77, and a water vapor absorption capacity of 30 kg/m²h½.
These are the values of a fundamentally solid building material, good in all characteristics, even top-class in water vapor absorption capacity and vapor diffusion resistance.

I think the mixture is what counts.
A lot of wood, cork, clay, and gypsum already contribute greatly to a positive indoor climate.

As much air passes through a wall as through a knotted balloon.

The concept is more relevant than ever

For whom? No one in Germany, since you can't and don't want to build like that anyway. Who would want a drafty hut with high heating costs. You write such nonsense.

I think it's the mix that matters. Lots of wood, cork, clay, and plaster contribute greatly to a positive indoor climate.

I agree. Especially with clay plaster, I have had good (and expensive) experiences. However, that has exactly 0 to do with air exchange or the like. Even a house equipped like that on the inside will immediately become dank if it is not ventilated.

Please finally be specific. Posting a randomly selected book cover does not support a single one of your statements.

I tried to get into Chapter 6 "Unsteady Moisture Transport in Components pp. 427ff". I have to admit that the differential calculations there initially overwhelm me and I am unable to explain them here in my own words. Besides, you yourself have not given a single plausible explanation for your position. That much for "specific".

For whom? Nobody in Germany, because you can't build like that at all and no one wants to. Who would want a drafty hut with high heating costs.

Please think first, then write. We are talking about diffusion-open and not windproof. These are two things that can be considered independently of each other and should be in this context.

You write such nonsense.

Just because it is not your opinion and contradicts your attitude?

However, that has exactly 0 to do with air exchange or anything like that. Even a house equipped like that on the inside will become musty immediately if it is not ventilated.

With diffusion-tight buildings, yes, with diffusion-open buildings you will not notice any mustiness, even if you grill kilometers of shrimp with garlic inside. Such houses also exist as holiday homes, try it out ;)

So I think wood and clay are great building materials, especially for the environment, but what you write here about diffusion openness of magic is not present.

I could not find any evidence and you have not provided any so far that CO2 would (significantly) pass through certain walls. Nor any other odors. Only water vapor passes through very slowly. It is stated as 1-2%. So practically negligible.