Clerestory

'clear storey', also clearstory, clearstorey, or overstorey; from Old French cler estor) is a high section of wall that contains windows above eye-level.

Historically, a clerestory formed an upper level of a Roman basilica or of the nave of a Romanesque or Gothic church, the walls of which rise above the rooflines of the lower aisles and which are pierced with windows.

[2] According to the Hebrew Bible, Solomon's Temple featured clerestory windows made possible by the use of a tall, angled roof and a central ridgepole.

The oldest glass clerestory windows still in place are from the late eleventh century, found in Augsburg Cathedral in Bavaria, Germany.

The ribbed vaulting and flying buttresses of Gothic architecture concentrated the weight and thrust of the roof, freeing wall-space for larger clerestory fenestration.

Generally, in Gothic masterpieces, the clerestory is divided into bays by the vaulting shafts that continue the same tall columns that form the arcade separating the aisles from the nave.

The tendency from the early Romanesque period to the late Gothic period was for the clerestory level to become progressively taller and the size of the windows to get proportionally larger in relation to wall surface, emerging in works such as the Gothic architecture of Amiens Cathedral or Westminster Abbey, where their clerestories account for nearly a third of the height of the interior.

[4] Modern clerestories often are defined as vertical windows, located on high walls, extending up from the roofline, designed to allow light and breezes into a space, without compromising privacy.

[6] Clerestories – in passive solar strategies – should be properly located (typically in the sunny side of the building) and protected from the summer's sun by rooflines, overhangs, recessed thick walls, or other architectural elements, in order to prevent overheating during the cooling season.