We’ve been worrying more about fire safety since we put secondary glazing on most of the old windows a year ago. All but one of our mullion windows are impossible to get through because the ancient oak bars are as strong as steel. The secondary glazing (or rather polycarbonate sheeting) makes them even more impenetrable.
Downstairs has no no internal doors, five external doors and two opening casement windows, so reassuring if any of the multiple smoke alarms go off. Upstairs, in the bigger of the old bedrooms, one big window has had enough mullions removed to make it easy to get through as an escape route.
The other 16th century bedroom has three tiny double casement windows. But only one casement on each of the three can be opened – the other side is fixed. A child could squeeze through but an adult would find it a challenge in an emergency.
The simplest solution is to make both sides of a window open. We chose the bigger of the three, which is also the one at the back with an easy drop, to try this out.
The central post (not sure if that’s the joiner’s term for it) was cut through top and bottom. The fixed side of the window was prised away from the frame, trimmed, and hinges were fitted, while still attached to the post.
It was then refitted to the window frame, with a new security latch and two bolts. So we now have a window even a large adult could get through easily. I have to admit, we should have done it years ago.
X
saving The Old Brewhouse 
Fascinating! While fire safety is always an immediate thought, it never occurred to me that you might be compromised by historic window style!
Glad you got it sorted.