A Brief History of Glazed Windows

There is evidence to suggest that glass was used by ancient Mesopotamian, Egyptian, and Chinese cultures to make a variety of artefacts including jewellery, lenses and vases. The dates of manufacture of this early form of coloured glass are undetermined but appear to go back to thousands of years. The Greeks and Venetians further developed the glass making process, but still the use of glass was restricted to producing items of decoration.

The Romans were the first civilisation to develop clear glass which may have been brought over to Britain under the expansion of the Roman Empire, possibly to be used in the windows of large Roman villas. The first known use of glass in windows coincided with the introduction of Christianity and the construction of churches, possibly dating back to the times of the rule of Charlemagne in the early 9th century. The origins of this, predominantly stained, glass would have traced back to France. Under Saxon rule, the use of stained glass in churches became more widespread.

Beyond this there is little knowledge of how the glass industry evolved in the UK before the 13th century. By this time though the Venetians had perfected the skill of producing clear, sheet glass, however the use of glass for windows in Britain still did not materialise much before the 16th century. Up to this time, for the vast majority of the British population, windows existed purely to fulfil the fundamental requirements of light and ventilation within the homestead. The window, whose name comes from the word ‘vindauga’ which is literally translated as ‘wind-eye,’ was quite literally a hole in the wall, with hinged wooden shutters to block out the elements. Glass was seen as a luxury, which only the very rich could afford, and few buildings besides churches and palaces had glazed windows.

Towards the end of the middle ages an increasing number of public buildings, inns and wealthy homes employed glazed windows in efforts to decorate and enhance their image. During the Elizabethan times there was much development of the flat-glass industry so that the use of window glass was facilitated lower down the social scale. The common window type for use with glass at this time was the lead-glazed iron casement, the usage of which peaked between the 16th and 17th centuries. These windows were poorly fitted though, and much less effective at reducing ventilation than the wooden framed windows that were in widespread use on the continent. Slowly, though, British attitudes began to change, advocating an improved orientation of buildings. In response the folding casement window was developed, which was considerably more efficient than the traditional casement window.

Soon after, circa 1669, the sliding sash window began to develop in Britain. By the 1680s the characteristic sash window had come to fruition and within another generation the technology was perfected with a counterbalancing mechanism that became synonymous to England. The glazed sash window was very popular for a multitude of reasons. For practicality it was extremely well suited to the British climate for both ventilation and weather proofing purposes. It was also less susceptible to being affected by distortion and rot. Aesthetically, due to the larger panes of glass, it provided clearer and better views of outdoor scenery, at a time when vistas of gardens and other exteriors had become very fashionable. Finally within the room it provided a quality of greater spaciousness. The glass in use between the 16th and 19th century was crown glass, where blown glass was spun into a flat cylinder. This process produced glass of a finer quality to any of the prior glass making techniques.

Due to its popularity the sash window became the dominant window variety and hindered the development of other window structures throughout the 18th and 19th century. In Georgian times the sash window evolved from having one fixed and one sliding sash to have two sliding sashes. Then in Victorian architecture the sash window became the focus of a building, with ornate arches and mouldings appearing in the forms of architraves. The casement window, though scarcer, was still in use in the 19th century, particularly in unison with the revival of gothic architecture. In the early 20th century both window structures were still in widespread up until World War I. During the 19th century and early 20th century glass making began to advance as the industry grew and many new glass types were uncovered including cylinder sheet glass, rolled plate glass and flat drawn sheet glass.

Post World War I the popularity of sash windows began to decline after two and a half centuries, at the expense of the casement window. The driving reasons behind this were mainly economical, as casement windows could be produced on mass incurring less labour and material costs. The casement window also proved to become more popular than the sash window in terms of style too. Despite this, the sash window remains a significant part of the heritage of Britain, and London in particular. Glass evolution took on drastic steps in the 20th century. In 1959 Pilkington’s float glass was introduced, which was practically perfectly flat and clear. Since then glass has continued to evolve into many versions including toughened glass, low-e glass, insulated glazing and self cleaning glass to name but a few.