Triple Glazing Insulation

A change in climate and carbon emission regulation means that some double glazing windows are no longer good enough to reach the standards set; even double glazing installed five to ten years ago is failing energy efficiency tests. This has led to more and more companies and people turning to triple glazing. Triple glazing insulation properties along with the acoustic benefits mean that it looks set to be standard place in all new houses.

Triple Glazing U-value

A good indicator of triple glazing insulation properties is to look at the U-value and Window Energy Rating (WER). The U-value measures how much heat is lost through a window and how quickly the heat escapes. The results of the U-value are graded A to E on the Window Energy Rating, “A” represents the lowest U-value and therefore the best window.  A triple glazing window has a U-value rating of just 0.8 which can reach 0.72 depending on the glass used, when compared to double glazing which has a U- value rating of around 2.8, triple glazed windows are far superior. The 0.8 rating means that triple glazing far exceeds the WER grading’s.


Triple glazing insulation properties are what set it apart from other kinds of window. The key is in the way that the window is constructed and the materials that are used. The three sheets of glass have to be spaced apart correctly to optimise heat reduction, even a millimetre out and the insulating benefits can be affected. Too close of a space reduces the radiant heat loss and too much of a space causes convection current loss. The space in-between the panes of glass are filled with an inert gas, argon is the most widely used gas as it is cheap to use and thanks to its low thermal conductivity it is around 33% better at insulating than air.

Low emissivity glass is another big part of triple glazing insulation properties, the inner and often the middle sheets of glass are metallically coated to produce a low emissivity finish. The coating used to achieve this is made up of a metal base substance painted on the glass in a thin layer, metals used can be:

  • Indium oxide
  • Gold
  • Silver
  • Copper
  • Rod- oxide

The spacers that separate the panes of glass are made up of carbon fibre to lower the risk of condensation, in early triple glazing unit’s metal spacers were more widely used but they were found to create cold bridges, which led to condensation.

Heat loss does not only occur through the glass, the window frame is also an important part of triple glazing insulation properties. Frames can be made up of wood, uPVC and aluminium and each frame offered will depend on the manufacture, combinations of the three materials are also produced. Frames that are imported from Scandinavian countries tend to come with wooden frames as they are cheap to purchase, use and are sustainable. Wooden frames also have tremendous insulation properties perfect for heat loss reduction.