Fire resistance in a sunshading element as an alternative design solution for fire retardant glazing

Abstract

This master thesis of the Building Technology track concerning fire resistance in a sun shading element as an alternative for fire retardant glazing was produced by the idea of Wiebe Schotanus from the Safety Region Haaglanden, who proposed the idea of combining sunshading and fire retardant properties as an alternative design solution for fire retardant glazing. The subject fire safety has grown in the past years into a major field of study, which is becoming more important in the building industry. This growth can also be seen in changes in the Dutch Building Decree the past years and in the built environment. Also in architecture there is an increasing demand for glass. Because of these factors also the demand for fire retardant glazing has increased as well as the demand for other fire retardant products and sunshading. In order to meet the increasing demand for glass in architecture, coupled with the increasing demand for sunshading elements and the growth of fire retardant products, in this thesis a concept design is developed for a fire retardant sun shading element as a design alternative for fire retardant glazing in public buildings. Herewith the chance on the development of fire by flash-over via the outside of a building should decrease and a cheaper design alternative for fire retardant glazing is proposed. To develop this concept research studies has been done to fire development, rules regarding fire safety in public buildings in Holland according to the Dutch Building Decree, fire retardant and sunshading products and materials in order to set a program of requirements. This is followed by simulations in the computer programs TRA and TRISCO in order to simulate the heat transfer during a fire in a room, especially in the glass and the façade and in order to determine the optimal distance between the window and the sunshading element on the inside. Also simulations are made with the same distances (75 and 100 mm) between the window and the element as the distances used in the measurements in order to compare them. With the use of prototypes made out of playing cards, wood and steel a couple of problems were solved and the mechanism to open and close the sunshading were tested. The mechanism of the fire retardant shading element closes automatically in case of fire, without the use of human effort or electricity. This is done by a wire which melts at high temperatures, with the result that the lamellae close automatically. At last measurements are performed in an oven of 700 degrees Celsius in order to test this self-closing mechanism and to measure the temperature rise in the glass in different situations, with the use of the fire retardant shading element and with two different glass thicknesses of 4 and 6 mm. The fire retardant shading element is tested at a distance of 75 and 100 mm from the window, in opened and closed situation and at last also a closed element with a fire retardant coating at a distance of 75 mm is tested. The system closed itself, because of the high temperatures and the melted wire, in around 10 seconds. One of the most important conclusions for as well the simulations as well as for the measurements is that how further away the element is from the heat source (fire), the less radiation it receives and how longer it takes for the glass pane to break. Also it takes longer for the glass to break when the 6 mm glass pane is used, because of the bigger mass. The fire retardant coating expanded because of the high temperatures from 1 mm to 20-30 mm, but did not have a remarkable effect on the time in which the glass pane broke. This probably because of the higher temperature in the oven in comparison to the other measurements and because of the conducted heat from the steel frame to the glass, because the frame was not coated or insulated and heat transfer from the steel to the glass was possible. But the fire retardant coating prevented the flames from raging to the outside of the element and the window when it was broken. So the element does prevent flash-over via the outside. Hereby a concept design is developed for a design alternative for fire retardant glazing. Naturally, this concept needs further study and more testing before it will become a definitive alternative design solution for fire retardant glazing.