Post 616 –by Gautam Shah
Sky lights have been used in buildings for ages for sourcing natural light into deep set interiors of buildings. These are set atop a roof, as a clerestory between roofs, or high up in the wall. These openings are basically meant for illumination and ventilation, occasionally for observing stars and other celestial objects and for cultivating plants in protected spaces. Such openings are minuscule size holes to very large gaps, often covering the room’s entire surface. Skylights allow maximum sky-component (SC) compared to any other opening system.
The Ras el-Tin Palace in 1931 Alexandria, Egypt > Wikipedia image Attribution: Bundesarchiv, Bild 102-12201 / CC-BY-SA3.0
In early periods such gaps were open or covered with a fabric, lattice, wooden slats or louvres. It was with the use of glass that such gaps became fixed-transparent panes. Roof-light openings with wood frames required frequent repair-replacements, and were not weather tight. During Victorian Era, with metal construction, skylights became very popular. Virtually every urban row house of the late 19th and early 20th C relied on a metal-framed skylight to illuminate the enclosed stairwells.
Skylights are were shaped as a pyramid because glass panes were flat. Very large skylights were designed with a structural geometry of curved half cylinders or domes, made from smaller units. These mainly bulged outward towards the sky for rain water drainage. Roof window or day lighting began to be flat or single-double curved structures with pre-formed toughened glass plates, plastics and fiber composites. Inverted daylights bulging inward into the interior volume are made from plastics and fiber constructions. Daylight tubes are inverse lights, as an inward projection of a reflective tube or a bottle.
Roof Lanterns were once very popular as interior and exterior illumination systems. These were timber-framed structures, usually octagonal, polygonal or circular in shape, placed as a crown over a turret or dome of a building to admit light. The lanterns’ structures were initially filled with wood slats (louvres) but later covered with glass. These were tall and thin volume multi pane glass structures. Roof Lantern or steeple lights during the day brought in shadow less illumination into the interior space. The lantern structures over the topmost point or pinnacle of a roof, glowed at night with little illumination inside the buildings. The glowing lanterns marked the presence of the building in the dark night-scape.
Roof Lanterns have derived from Orangeries, structures first built in 16th C in France and Italy. An orangery is similar to a conservatory or greenhouse. It is generally located in the free ground of an estate or building. The name reflects the original use of the building as a place where citrus trees like orange were often wintered in tubs under cover, for surviving through harsh frosts, though not expected to flower and fruit.
Orangeries originated from the Renaissance gardens of Italy. The orangeries became fashionable in ordinary residences of France, Germany and the Netherlands. Early orangeries had large windows but opaque roofs. Glazed roofs were developed in the early 19th C. Early orangeries, as existed in Great Britain and France in 16th C, were buildings that could be covered by planks and sacking and heated in the cold season by stoves.
During the Georgian era, buildings with large footprints (floor area), the interiors were dim and dark even on sunny days, and in absence of electric or gaslight candle power was the only source of illumination. Roof lanterns were used to illuminate the stairwell landings and other areas of home. The key element of a lantern, the glass was hand made and very expensive, limiting the use of roof lanterns in the homes of elite.
The Crystal Palace built for the Great Exhibition of 1851 inspired people for greater use of glass in roof structures of buildings, and the Industrial revolution provided the necessary affluence and technology. Modern Roof lanterns were used for illuminating domestic billiard rooms, reception rooms and kitchens, and in public buildings such as hotels, in places of education, town halls and public libraries.
DORMER WINDOW: A dormer is an attic window located in the sloping gable roof, on the main face of the building. A dormer is an extension of the attic and provides accessible or functional height right to the front edge of the room, which is used for placing a bed or study unit. The roof over a dormer is slopped cross way from the slope of the main roof. The dormer windows are design-matched with the window of a lower floor, creating an impression of a taller window, both from outside as well as inside. Dormers add a visual interest to the nominally plain gable roof surface. In England when fire laws did not permit architectural projections such as eaves, etc., the front wall was extended as a parapet to cover up the roof end. The parapet was articulated with embattlements, crenels, embrasures and dormers. Wall dormers are lower floor windows extended up to roof, parapet top, or even higher, as a true or dummy window, with all features of an highly ornamental window surrounds. False or blind dormers were added to visually balance roof-leveled other appendages, like chimneys, lanterns etc. Dormer openings are also called a doghouse, because the form of the dormer resembles the pet-house. Attic level barn windows shaped like a dormer used for taking in or out hay are called hay-windows.
Types of Dormer windows: A gable dormer, has sloped roofs on both sides. A hipped dormer has a roof sloping on three sides including front. An insert dormer is set back from the sloping edge of the roof so has some sloping roof on its front bottom side. A turret dormer has multi angled hipped roof. A French segmental dormer has lower floor window continuing above by breaking the line of roof eaves. A fanlight dormer and Eyebrow dormer has rounded top window. A shed or lean-to dormer has single slope roof. An extended shed dormer has roof line extending beyond the main roof line. An all glass contemporary dormer has all sides formed of fixed glass or jalousie.