We are fortunate that we have two means of reasonably easy escape from upstairs windows. NONE of our windows are locked. All have locks on them but the keys were binned. I would never lock the windows.First thing any householder/tenant should do is to draw up an escape plan and make sure every member of the family understands it
When the kids were little but old enough to dress themselves and sleep in separate rooms, I went through the evacuation drill with them. It resulted in my youngest going walk about on the roof on one occasion eek but at least they'd know what to do in a fire.