Weiß jemand, was das für Fenster sind und wo ich Griffe finde, um sie zu öffnen?

https://www.k-rauta.fi/tuote/ikkunan-avain-prof-valkoinen/6438313581079

There’s a square hole that should be more or less standard size. Any hardware store would have the handle available, or you can even get it from Prisma: [https://www.prisma.fi/tuotteet/100063191/sg-ikkunan-irtopainike-kromi-100063191](https://www.prisma.fi/tuotteet/100063191/sg-ikkunan-irtopainike-kromi-100063191)

In this climate many windows are not regularly opened, so there is no permanent handle.

Try Tokmanni or Prisma. Ikkuna-avain is what you need.

By any chance, does the handle at the bottom window come off? Because it looks like it would fit to the rest. You have to use the handle to open each of those locks

If you have screwdriver you can use that opener from under window

First you should check all the cabinets in your apartment/house, especially those in the kitchen. The handle is probably hiding in one, look into the top shelves.

Second, you should also see if your ac unit has a window installation kit available. You’re better off putting the exhaust duct out of the little window, not the bigger one.

The big window is designed to be opened for cleaning, not for general ventilation. Like others mentioned you should try to fully open the ventilation window below and attach your AC vent there, assuming you mean a portable AC unit and not a wall mount one.