Sash windows are sliding windows that came into use in the 17th century, according to the BBC. They were originally held open by pegs, then counterweights, although modern sash windows stay open on their own in most cases. Like all other windows, sash windows get dirty and need cleaning from time to time in order to maintain a sparkling appearance. Using a window cleaner with ammonia is a good option for sash and most other types of windows.
Lower the bottom of the sash window to a height that you can reach over comfortably. Spray the outside of the sash window with the window cleaner and wipe it off with the cloth, scrubbing any heavily-soiled parts as needed.
Raise the lower sash window and lean out to spray the bottom of it with window cleaner, then wipe it clean with the cloth.
Close the sash windows completely and spray the inside of the windows with the cleaner, then wipe it clean with a cloth.
Spray wood cleaner on a clean cloth and wipe down the wooden window seals and wooded casing around the windows, being sure not to touch any of the glass.
Do not reach out of the sash windows needlessly or lean on them for support. Only reach out as far as you comfortably can when cleaning.