Potential Hazards in Glazing Above Public Areas

Overhead glazing can be very attractive, particularly when used over a large area and to highlight structural or architectural features. Use of glass in modern structures is often desirable as a sustainable means of increasing interior light levels, decreasing energy consumption through natural heating/cooling and ventilation, and for a variety of aesthetic reasons. 
Some types of glass and construction can present a potential risk to those in close proximity if failure occurs. Significant invisible defects may be present in some types of glass and methods of construction which only become apparent when panels spontaneously break without any immediately obvious cause. Such latent defects can exist in toughened glass and remain hidden for many years before producing explosive-type failures. 
This paper briefly reviews types of glass currently available for construction and discusses modes of failures and potential hazards and risks that they represent. A case study of a failure of overhead glazing (where a large number of panels spontaneously failed over a period of several years) is discussed, together with the likely causes and solution. The paper concludes with recommendations for "best practice" for overhead glazing, and useful information for practising engineers wishing to use glass in their designs.