Double Glazing Specifications

Updated April 17, 2017

Double glazing refers to window installations where there are two panes of glass instead of one. Double glazing reduces heat loss and helps keep your house warmer while using less energy. The extra pane also reduces noise transmission. As this is a time- and money-intensive procedure, you need to consider many factors. Learn about some of the specifications, recommendations and information involved with double glazing.


Double glazing works in two ways: the extra window pane reflects the heat back into the room instead of allowing it to escape. This traps the solar energy better to heat the room naturally. estimates that by using the most efficient glass insulation, a household can save over £9,100 over a 20-year period. As energy costs rise, the amount saved could increase. In the summer, when you don't need heating, the extra pane works in your favour by acting as a barrier against heat loss through heat-conducive glass.

The Cavity

The cavity between the window is not simply empty space. It plays a vital role in the double glazing system. The space between the window is sealed using a special procedure that uses both primary and secondary seals. The space is filled with dehydrated air or inert gas. Gases like argon, xenon, krypton have a much lower thermal conductivity than air. The energy efficiency increases even further as the gas between the windows acts as an additional energy barrier.

Choosing Windows

You have several options for which kind of glass you choose. Several other factors work to your favour. Glass used in double glazing installations is known as Low E, meaning it is low-emissivity glass. Within the Low E category, the glass is rated on a scale from A to G, with A being the most energy efficient and E being the least. Another factor, U rating of the glass, measures the ability of the glass to transfer heat well. Glass with the lowest U rating is the most efficient in trapping heat inside the house and not transferring heat through the glass.

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