Windows

Windowshapes ... rooflights ... atriums ... glazing ... high tech glazing ... window openings . . . symbolism . . . solar shading . . . privacy . . . innovative systems . . . the future

The window is an opening in a wall or side of a building admitting light and often air to the interior. Early windows were developed before the introduction of glass, so initially windows were left open to the external atmosphere, or filled by some form of closure to minimize the heat loss at night. The more sophisticated buildings would have had thin slabs of marble, mica or oiled paper for this purpose.

In mediaeval times wooden shutters were installed on the interior, and these were left open or closed to regulate the light and air. With the introduction of glass, used first in small panes in Roman architecture, the window as we know it today had its beginnings. The concept of small panes of glass, divided by bronze or later lead divisions, as used in early buildings dies hard and window manufacturers still offer these as

Carpenters'shop, Weald and Downland Museum alternatives to fully glazed windows in new domestic work, however inappropriate they may appear.

Windows can broadly be divided into two main types, first the window set in the side walls of a building, and second the opening light set into the roof, generally known as rooflights.

The daylight penetration from side windows will depend upon the ceiling height, and in early buildings where the ceiling heights were low, the penetration of daylight into the building was severely limited . . . with the design of the important houses of the seventeenth and eighteenth centuries the ceiling heights were raised and daylight was able to reach further into the interiors. However as buildings became grander, even

Clerestories, York Minster Soane Museum frontage

Carpenters'shop, Weald and Downland Museum

Georgian window, Soane museum

this was not enough, and the concept of the rooflight was developed to introduce daylight into interiors far from the side windows.

Illustrations of some window types indicate the variety of window shapes that have evolved over the centuries, set into the vertical sides of buildings.

The horizontal window is perhaps the most well known of all, starting as it did in mediaeval times, limited by the construction methods of the day. It is still much used in today's domestic architecture. Provided the horizontal window is placed high in the wall the daylighting will penetrate well into the space, but other features of the window need to be considered, such as the view out which will be prejudiced where the cill is too high.

A logical development of this type is where the horizontal window extends the entire length of the external wall, a device used in nineteenth century industrial buildings to provide even and sufficient light for machine operators. This type of window required new structural techniques to overcome the need for vertical support to the structure above.

Yet a further example is the clerestorey; found mainly in tall buildings such as churches, generally associated with other forms of window at lower level to provide the main daylight. Clerestoreys are placed at high level to assist in getting daylight further into the interior and to light the roof structure.

A logical development of the extended horizontal window, is the floor to ceiling window; as structural techniques were perfected, this type of window has become almost universal in some types of architectural programme such as the office. The 1930s saw the innovation of the wrap around corner window as further structural techniques were made possible.

Orange Operational facility

City Hall, London. Interior/exterior

Finally and in no chronological order comes the vertical window. Vertical windows were popular from the fourteenth century, having perhaps their most glorious period in the eighteenth century, when the Georgian window with its sophisticated detailing was almost universal. Tall windows, set apart by masonry at intervals, provided a simple structural solution and this formed the pattern of development in residential and other building types for several centuries.

The window can be said to be the most important architectural feature of a building; this is the first experience that a visitor will have when seeing the building for the first time, and architects have naturally considered the form of the window and its relationship to the exterior to be vital.

Three buildings on London's Embankment

The illlustrations of these buildings along the Embankment illustrate three different approaches to fenestration. All buildings are of the twentieth century. The first, on the left, shows the more traditional separate windows, whilst that in the middle is an example of the continuous horizontal window, where the individual floors are expressed as important horizontal bands. The building on the right is the further development where the window becomes a subsidiary part of the external cladding, for a total glass facade. The appearance of the buildings says little about the success of the daylighting, it says more about architectural fashion.

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