A.4 Insulating Glass

To reduce heat, gain, or loss through the glass, two or more lines of glass are used to create dead air space that inhibits the transmission of heat and cold between the lines of glass. Insulated glass is typically fabricated using very special sealants and a metal spacer at the perimeter of the glass- creating a hermetically sealed insulated glass (IG) unit. Glass used in IG units can be annealed, heat-strengthened or fully tempered.