What is double glazing?
In the past, windows have been constructed with one single pane of glass only. Because single glazed windows are only a few millimetres thick, they serve as poor insulators - meaning it is easy for heat and cool air to pass through them. Today, double glazing is a more energy efficient solution that consists of two panes of glass with an air gap in between. The combination of two panes of glass and a locked air gap turn the windows into strong insulators rather than energy drains. The width of the two panes of glass and the air gap vary depending on the needs of the climate, exposure to the elements and orientation of the windows to the sun.
Some older windows can be retrofitted with double glazing, however today most double glazing units are manufactured as one single unit. The two panes of glass are sealed together and inserted just as a single pane of glass would be.
The sealed air gap between the glass improves insulation performance, which greatly reduces both heat flow and thermal conductivity through the window.
Benefits of double glazing
Double glazing the windows and doors in your home will save you energy, money and improve comfort year round.
- Added insulation
- Reduced solar heat gain
- Minimises heat flow between the outside and inside of your home
- Reduces noise pollution without obstructing the view
- Retains natural light flow into your home
How does double glazing work?
The sealed air gap between the two panes of glass significantly improves the insulation performance of the window. This gap acts as a buffer for the difference in temperature outside and inside the home.
Solar heat gain, which is the heat created inside your home when sun rays heat up a window, is greatly reduced with double glazing, as the outside pane of glass absorbs some of the heat, and reflects the rest back out. At the same time, the air gap between the two panes of glass stops this heat from moving through the glass inside. This makes double glazed windows more energy efficient - especially during the summer months, when the sun’s rays are much harsher, while keeping a cool and consistent temperature inside as a priority.
Thermal conductivity, or the flow of heat through glass, occurs when there is a difference in temperature on either side of the glass. In a well insulated home this makes it hotter outside in summer, and warmer inside in winter. Heat flow is when this heat escapes in winter, meaning you need more powerful heating to keep your home at a comfortable temperature. In summer, this heat leaks in from the outside, making your air conditioning work harder. The improved insulation performance of double glazing works to minimise the heat flow through glass. By stopping the heat at the first pane of glass and reflecting it back - either retaining the heat inside during winter, or reflecting it back outside during summer, it helps maintain a constant temperature in your home.
How do double glazed windows insulate?
The unique combination of dual glass panes and air make double glazed windows an energy saver rather than an energy drain.
More glass = better insulation
Because double glazed windows have two panes of glass instead of one, it is difficult for heat to pass through. The thicker the glass heat has to try to pass through, the better at insulating it is.
Trapped air = better insulation
The air locked between the two panes of glass in a double glazing unit is the main source of insulation. When a material is hot, its molecules move quickly, spreading the heat. Air molecules are spread out, meaning they cannot spread the heat as quickly as in a solid mass, like glass or timber. Because this air gap slows down the movement of heat through the window, it acts as a very good insulator.
Are all double glazed windows the same?
Double glazed windows come in a range of variations, suited to different climates, exposure to the elements and budgets. For more product information visit our FAQS page.