The problem is that the windows might not be suitable for window units. For instance in the Netherlands our windows typically tilt or turn (like a door) open, they don’t slide up. The walls and ceilings are usually solid brick or concrete, so you can’t hide ducts in there for central AC. That leaves a split unit in one room or a portable unit.
Blocking the light made a huge difference in my house. I have are 3 small skylights on the south side that now have sun shades on the outside. They still let in some light, but it’s at least 5c cooler on the top floor.
People from the "hotter" regions, how do you deal with the heat?
I am from Eastern Europe and this is the hottest summer on my memory. For at least 3 consecutive years the heat is breaking all records....