Insulation is a property mostly needed in a home. In a single glazed window, the air between the room (the warmer air) exchanges energy with the air outside the room (the cooler air). This exchange of energy or heat occurs by the natural process of convention or conduction.
This process ensures that the room gets cooler as fast as possible. More so, this is the reason why rooms cool up quickly in a winter or cool weather condition. The heat loss by convention and conduction can however be reduced by leveraging the concept of double glazing.
When a double glazing window is used, heat is still lost but in this case the heat lost is greatly minimized. This ensures that the loss of energy inside the room is greatly reduced and therefore energy can be saved in a home. Most home using double glazing windows end up saving a lot of money which adds up to compensate for the money they used in purchasing the window in the first place.
Single glazed windows are cheaper than double glazing windows but the truth is that the savings that is accorded by the double glazing combination makes it a cheaper way to go.