So essentially while trying to build an anti-green house I ended up building a normal green house. But that’s actually exactly the answer I was looking for, thank you a lot! It was not so much about the practicality or whether there are better solutions but about whether I am missing something. (My other guess was that this light reflection would only work in the stratosphere to begin with.)
I’m a millennial living in a rented apartment so I cannot/could not implement anything. But we do indeed have trees in front of our windows, we have heat exchangers in two out of three rooms, PV on the rooftop and the house (built in 1900) is painted white (apart from the roof). Needless to say AC isn’t a thing in my country. Currently we have slightly under 26°C in our apartment. And my parents have a (very white) house with what you call a living roof, that’s a great name for that which I wasn’t familiar with before. Again, thanks!