What is insulating glass? Insulating glass is a combination of two or more panes of glass with a hermetically sealed spacer between the panes of glass. The function of insulation glass is to reduce sound, and thermal losses and , which offers the advantages of lower energy consumption and perfect transparency. Thickness: 5mm-12mm Airspace:6mm/9mm/12mm/16mm Min size: 300*300mm Max size: 6000*2440mm.