It is made with two or more plies of glass, separated by a spacer that is filled with desiccant to isolate glass. At the same time, hollow portion is filled with dry air or inert gas and sealed with butyl rubber, poly sulfide rubber and structural adhesive to ensure is air tight. It is possible to combine with tempered glass, heat-strengthened glass, laminated or even curved glass. However, for higher performance glass is best suited with combination of Low-E Glass. IGU is of flawless quality with high degree of resistance to heat, retarding the flux of heat during the summer and heat loss during winter. It saves electricity being used for heating or cooling by decreasing air to air heat transfer. The air enclosed within the insulated glass panes makes insulating capability twice of monolithic glass. Therefore load of air-conditioning is greatly reduced, with insulating glass; the insulating effect of air layer makes it tough for the glass to become cold and is relatively difficult for dew condensation.