Large opening paneled window

[nickjb]

We currently have an 8 paneled window like the top left window in the pic below (not the actual house, just a reference pic). It's above a flat green roof and used for occasional access for maintenance by climbing through one of the end lower panels. Not too bad but could be better. As the window needs replacing I'm looking for options to get a bigger opening but keep the same look. Could I get a window with glazing bars to make it look the same but have a larger section open (does this have a particular name)? Any other options and who might be a good supplier? White Upvc

 

[Gazman16]

You could include a flying mullion opener. Basically 2 side opening sashs side by side that open like french doors, The mullion is attached to the slave sash.
You may want to add dummy sash's to the rest of the window to equal out the look of it too.