Window glazing
How do double and triple glazed windows help keep our homes warm?
Modern double-glazed windows consist of two layers of glass bonded together in one frame, allowing for better insulation and fewer drafts, meaning cheaper heating bills and a quieter home.
A single-pane window can transfer heat through conduction, convection and radiation. This is why on a cold day a single pane of glass can feel much colder than the air. So how are insulating glass windows engineered to reduce the loss of heat from a house? The trick is filling the gap between the panes of glass with air. By providing a blanket of dehydrated air, the rate of heat loss through the window is reduced because air is a poor thermal conductor.
Double glazing has been on the market for over 40 years, and triple-pane glass is becoming increasingly popular. Triple-glazed windows consist of three panes of glass separated by two air chambers. The two external glass surfaces also have a low-e (low emissivity) coating to reflect infrared light. This helps to stop up to 97 per cent of the thermal energy from being transferred across the panes, reflecting the heat instead.
This undoubtedly makes a difference. The efficiency is measured by recording the surface temperature of the glass. The PassivHaus Institute in Germany tested this and found that when the internal temperature of a room is 21 degrees Celsius on a cold day, the internal surface temperature of a single pane is approximately one degree Celsius. However, they found that a traditional double-glazed window would see temperatures nearer 11 degrees Celsius, whereas triple glazing has a surface temperature of 18 degrees Celsius.
“Triplepane glass is becoming increasingly popular”