Painting works for prefabricated house: Which interior paint? Painter's fleece?

Hello, we are currently in the middle of building our prefabricated house and it is about the painting work. In the standard of our general contractor, everywhere is patched with Q3 and painted white using dispersion paint. After the first conversation with the painter, we still have many question marks...

Regarding the paint, it is important to us to use a paint that is as pollutant/emission-free as possible, as my wife is very sensitive in this area. As an alternative to dispersion paint, I had already read something about silicate paints/silicate dispersion paints, although there are always indications that they are not very suitable for gypsum plasterboards. Alternatively, I think emission-free/certified dispersion paints would also be an option. I have the information from the painter that a certified paint ([blauer Engel]) would cost €3.2/sqm net more than the standard, which I find quite a lot.

Additionally, the painter recommended that we use painting fleece everywhere, which would cost an extra €8.2/sqm net and of course would be quite a big chunk again. Since we have many large windows facing south, he said that raking light would otherwise be a big problem.

Can anyone say something about these points and help reduce our question marks? ;)

so we had painter’s fleece applied in all rooms except the utility room and painted with washable paint. He had to come a second time because there were slight dents in two places that caused some shadows. It was sanded again and the painter’s fleece was reapplied. Then it was painted and now it’s perfect. You usually only notice it afterwards when you have the specific lighting conditions along with furniture and furnishings in place. It was mostly only visible in the evenings. Since we chose indirect lighting, the two spots stood out extremely.

So yes, I claim that without Q4 processing, there will always be visible spots without painter's fleece. You can also apply silicate on gypsum, but it simply does not silicify there. Some people then exaggerate this fact towards "it is not sensible." It is just another advantage that does not come into play (silicification is a connection with the substrate, so the paint adheres not only to the wall but is basically "in" the wall). Silicate paint itself is still diffusion-open and highly alkaline on gypsum and therefore mold-inhibiting. But yes, the surcharge is steep. I was quoted a surcharge of 2 EUR / m² (2020) for painter's fleece, but in the end I completely removed the painter's service.

In the living areas it will definitely be painter's fleece. I think for the children and us in the bedroom it's not so important now whether the wall still has small unevenness.

Again about the colors: An important difference between silicate and dispersion paint is the diffusion openness. We have a controlled residential ventilation anyway and thus hopefully no problem with moisture. Is the topic of diffusion openness still relevant then? In terms of pollutants, individually certified dispersion paints (E.L.F. plus, Blue Angel etc) don't seem to be worse than silicate paints...

Well, it's like with the sacraments, Catholics have seven, Lutherans three.

1. Nowadays, dispersion paints are also vapor permeable (at least according to the standard, if sd <0.5m)
2. In my opinion, the vapor permeability is overrated.
3. If anything, you have to be vapor permeable in the entire wall construction, from interior paint to exterior plaster.

But (dispersion-)silicate paint is still to be preferred over dispersion paint (in my opinion), because the high alkalinity greatly hinders mold growth.

On the other hand, millions of buildings are painted with dispersion paint over dispersion paint on three layers of wallpaper and there are not as many mold cases...

Does silicate paint have disadvantages besides the price, and what surcharge would be justified? I find a surcharge of €3.8/sqm from standard dispersion paint to certified dispersion paint really steep, or can that be explained by anything other than rip-off? I looked at both paints in the common online shops, and there it is only about €1.5/liter difference, which might amount to 50 cents per sqm...