The ducted exhaust of 'vitiated air' was removed through grilles near or in the ceiling.
At the same time, teenagers - barred from the grilles because of their youth - established their own public dance spaces, called aguelulos.
These grilles and apertures were the weak points in the system of enclosure, across which nuns made their transactions with the outside world.
Each riser skips the basement level but has an opening to a floor grille on each of the three floors above.
Relations between nuns and priests or friars took place on the peripheries of enclosure : in the parlatorio or at the church grilles.
Neither plane is interrupted by the mundane requirements of twentieth-century living - no lighting or grilles.
When seculars entered convents, their contact with the sisters was regulated strictly by grilles and partitions in the parlour (locutory) and the church.
These are directly connected over a fixed baffle with exterior grilles that are hardly visible among the exterior masonry.