Operable transom

Operable transom

A pane of glass above a door, which may be opened for ventilation.

operable transom

A panel or glass light, above a door, which may be opened for ventilation.
References in periodicals archive ?
Above all the doors are operable transom windows, again allowing for cross-ventilation and heat exchange, even if the doors are closed.
A system of ventilation shafts were uncovered, that were created to work in conjunction with a central atrium and operable transoms to induce air 'flow, and combined with the thermal dampening of this building's heavy mass made its system's extremely effective.