Double pane windows are manufactured as airtight units that are able to resist fogging due to a material in the spacer called desiccant. When either the inner or outer piece of glass breaks, the desiccant becomes saturated resulting in loss of insulating value of the unit. Although replacement of an insulated unit is more expensive than single pane glass, the benefits far outweigh the cost. Besides the obvious energy savings benefits, insulated units will also provide important security benefits. In most circumstances, only one of the two glass panes are broken, thus still securing the space until the replacement window can be installed.