Can a Upvc window be changed from opening at the bottom to opening at the side the window is the same measurement on all 4 sides
Yes it can(if it is exactly square). Move everything around 90º the frame. You will have to remove the glass and repack it differently(toe & heel). You may also have drain holes to redrill out, as any that were in the bottom will now be up the side. The side hinges (friction stays) will now be top and bottom and should be fine. If it is a large window though, depending on the length of hinges, you may need longer ones. Can be done.
Thanks it's only a small window, but wanted to make sure before I ask someone to do it. Didn't want to look stupid.