Easy cleaning glazing on school, Barcelona 
These are images from Blanquerna School in Barcelona which show the interest in typological research. Each of the large glazing is divided by a horizontal crossbeam in two equal parts. Below a crossbar divide the hole in two practicable leaves. Above the same single sheet is subdivided into four panes, moving all together as a guillotine. When opening the two inferior leaves, the guillotine blade can slide down and pivot to a horizontal position to facilitate cleaning.
The first photo is from the early years of the building. Nowadays some of this wooden joineries have been changed, maintaining the exterior image, but in some cases loosing this richness of movements.
In this schematic sketch, we can clearly see the possible combinations of movements of the window.