deleted by creator
1 year later, it seems to be offline :(
For Android i know that you can find some FOSS Telegram clients, in github and telegram itself but also on F-Droid (just to name a few: Telegram FOSS, Nekogram X, Forkgram, Catogram).
On desktop on the other hand, i know of only one other FOSS client (that is called: Kotatogram).
Maybe someone knows of some more FOSS desktop clients?
You could try cooling only your body instead of cooling down the whole room. A solar panel + powerbank + portable (battery powered) usb fan could be a good solution for this. Combined with the other forementioned tipps it should be even more effective.