Transmission Through and Breakage of Multi-Pane Glazing Due to Radiant Exposure

A series of small and large-scale tests were performed to measure the radiant transmission of energy and the window breakage characteristics of seven different multi-plane glazing samples. The samples tested included both double and triple-pane glazing specimens with a laminate interlayer between panes for additional strength. These test series were designed to provide the information necessary to assess the hazard from radiant energy to building occupants and contents due to a large fire in close proximity to a structure with a large amount of exterior windows. For incident heat fluxes 30 kW/m² or lower, the triple-pane glazing samples had a total transmittance less than 10% of the incident heat flux, back-side surface temperatures did not exceed 100°C, and the back-side heat flux did not exceed 4 kW/m². For double-pane laminates, the total transmittance was less than 25% of the incident heat flux, the back-side temperature did not exceed 220°C, and the back-side heat flux did not exceed 5 kW/m². For incident heat fluxes greater than 30 kW/m², the glazing samples degraded very quickly, generally buckling and losing integrity. The time for the first pane to crack decreased with increasing incident flux level. A number of tests included a water deluge system, which served to maintain sample integrity for extended exposures. In these cases, the total transmittance was less than 6% of the incident heat flux, back-side surface temperatures did not exceed 45°C, and the back-side heat flux did not exceed 1 kW/m².