Pros and Cons of Ventilation and Exhaust Systems

...we have it more or less the same way, although the cooling performance is more of a support.

My dream is that in summer an air conditioner is powered directly from the roof...

What could be more sensible than using the sun, which makes you too hot, to cool down again? By the way, this also exists at Maybach!

Why don't you do it? An AC isn't that expensive, and neither is photovoltaics....

Photovoltaics I would have (or rather my father on the jointly used property). However, there is still a decent remuneration for several more years. Self-consumption is therefore not worthwhile yet.

And the living room has quite a few cubic meters, as it is open up to the roof. So it probably won't be cheap... But another summer like this one, then the piggy bank will surely be slaughtered!