Construction costs are currently skyrocketing

For everyday use, I still find recirculation better in new buildings because you don’t damage the wall and can use the hood independently of the supply air. With exhaust air, you always push the warm indoor air outside, which is also a factor (albeit a small one). Moisture is no issue and irrelevant with controlled residential ventilation.

You have to ventilate the kitchen anyway. The dishwasher also produces moisture because the modern models no longer reheat but simply open 5-50 minutes before the program ends. Cooking produces moisture. The kettle and the coffee machine produce moisture.

The exhaust hood blows the moist air directly outside. The recirculation hood first distributes it in the room; some goes into the living room, some into the hallway. And then you ventilate crosswise for 20 minutes so that the moist air is outside again.

In both cases, you push the warm indoor air outside... where is the difference? The difference is that with the exhaust hood, stage 2 is enough, but the recirculation hood has to run on stage 5. Because the air becomes increasingly saturated, the hood removes less and less. So more air has to be drawn through. That costs electricity again. Also, the power needed to press air through the filter is much higher than the power an exhaust hood needs to simply push the air through a hole in the wall.

And whether the 0.05m² my exhaust drill hole in the facade makes... equipped with a wall box, there are now energy-saving versions that only open when the hood is on, otherwise a flap closes that insulates...
Whether this 0.05m² minimally affects heating energy consumption... in the kitchen it is always warm when cooking anyway... at least for me. I haven’t managed to cook cold yet.

Your documents from KfW should mention something about a 10-year deterioration prohibition. In other words: even a core drilling and exhaust hood would be illegal. Whether anyone actually checks that, of course, is another question.

Interesting topic. Can anyone actively report on something like this? I mean subsequent inspections by KfW.

Interesting topic. Can anyone actively report on something like this? I mean subsequent checks by the KfW.

Yes, it happened to our energy consultant a few years ago. Basically possible, but in his experience randomly at 0.x%

There is a difference between exhaust air without heat recovery and ventilation with heat recovery. In the first case, the heat stays inside and the moisture goes out, in the other both go out. And now we can do a little calculation. Heating 1cbm of air by 1 degree requires 0.33Wh. With a 20-degree temperature difference and 500cbm air exchange, 3.3 kWh of heat energy is lost through the exhaust hood. With recirculation hood and ventilation with 80-90% heat recovery, only a fraction of that is lost. In grandma’s unrenovated little house from 1965 with 250 kWh/sqm that doesn’t matter. In new buildings, it does.

The warm indoor air is pushed outside in both cases... where is the difference?

The difference is that, because of the moisture sources you mention, I do not ventilate. That is done by the controlled residential ventilation system, and my living/dining/kitchen area is 55 sqm in size. Nobody gets foggy glasses from a boiled-down soup there :)

We still haven't found an affordable tiler and have now turned to the platform with the hammer. So far, received one concrete offer....for 37m2 with skirting boards offered just under 5000 EUR, which is even more expensive than what we have been offered so far^^. But it is quite easy to get in touch with interested companies, which is definitely an advantage. My expectations are around 3000 EUR, is that really that low?? I actually think it's fair for both sides.