right a guide on how to open and clean a sash window
open bottom sash a few inches, pop the two clips on left hand side into position and drop the window into the gaps
on right hand side is a length of wood with a small screw, remove the screw, then remove the wood
grab the rope if it has one and swing the window inwards,
this part can now be cleaned safely
top sash if small enough drop down into to the halfway down position, stand on sill lean out clean top half, get on floor and lean out and clean bottom half
push it back up and a reverse of part one for the lower half done
large sash same for part 1 if you can be bothered or just push up window connect safety harness to certified eye bolt, remember to wear the harness get out the window close it and pull down the top window clean it then push it back up, clean bottom window then open it get back inside, unconnect from eyebolt close window done.
the building owner is responsible for the fitting of eye bolts and making sure they are certified yearly
explain all that to them and the fact all windows need serviced so they do slide up and open in etc
and you might find the barge becomes an option