WINDOW TECHNOLOGIES: Glass
Laminated glass consists of a tough plastic interlayer made of polyvinyl butyral (PVB) bonded between two panes of glass under heat and pressure. Once sealed, the glass sandwich behaves as a single unit and looks like normal glass. Laminated glass provides durability, high performance, and multifunctional benefits while preserving aesthetic appearance.
Similar to car windshield glass, laminated glass may crack upon impact, but the glass fragments tend to adhere to the plastic interlayer rather than falling free and potentially causing injury. Laminated glass resolves many design problems, offering increased protection from the effects of disasters such as hurricanes, earthquakes, and bomb blasts.
Annealed, heat-strengthened, or tempered glass can be used to produce laminated glass; the glass layers may be of equal or unequal thickness. With respect to solar control, laminated glass retains the characteristics of the glass making up the assembly (see figure to the right). Reflective coatings and frit patterns may also be applied within a laminated glass sandwich. Laminated glass can also be used as a component of an insulated glazing unit.
Single-pane laminated glass with a spectrally selective low-E sputtered coating on plastic film sandwiched between two panes of glass offers the energy performance of single-pane, spectrally selective glass and the safety protection of laminated glass. However, in this configuration, since the low-E surface is not exposed to an air space, the lower emittance has no effect on the glazing U-factor and SHGC. With double-pane laminated glass, the full benefit of the low-E coating can be realized by placing the coating on one of the glass surfaces facing the air space.
Glass has inherently poor acoustic properties, but laminated glass, alone or combined with additional glass plies to form a sealed, insulating glass unit, outperforms other glazing assemblies. Laminated glass reduces noise transmission due to the PVB layer's sound-dampening characteristics.