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The right glazing choices can help make your home more comfortable in hot and cool weather.

There are several glazing options available. Some keep heat inside your home. Others keep heat, noise, light and glare out.

Glass options

There are several other types of glass available:

  • Reflective glass, tinted glass and spectrally selective glass reduce the amount of heat and ultraviolet light that can get in (ultraviolet light causes fading).
  • Laminated glass is two sheets of glass bonded with a plastic or resin layer. It absorbs ultraviolet light and reduces noise. If its hit, the glass is held together by the resin layer.
  • Toughened safety glass is much stronger than standard glass. Its designed to withstand direct impacts or shatter into small chunks if broken
  • Laminated glass is the best option for noise, as well as being safe and secure. Reflective, tinted and spectrally selective glass are options for keeping summer heat out.

All of these types of glass can be used with double glazing, which is the best option for winter comfort.

Double glazing

What is double glazing?

A double-glazed window uses two panes, separated by a gap which is filled with air or an insulating gas such as argon. It is also known as an Insulating Glass Unit (IGU).

Although gaps can vary between 6 and 12mm, a 12mm gap is assumed in most R value calculations.

You can vary the glass you use for the two panes in a double glazing unit, and you can choose two different types of glass for each pane.

If you are retrofitting double glazing to your existing windows, there are three main options: replacing the whole window frame with new frames and glass

  • installing inserts into your existing window frames this is a cheaper option if your window frames are still in good condition
  • installing secondary glazing.

How effective is double glazing?

Double glazing can make a big difference to comfort levels in your home. Combined with insulation in the walls, ceiling and floor, double glazing your windows and doors will help keep temperatures stable and reduce heating and cooling costs.

By double glazing a window with clear glass, you can halve the heat loss compared to a single-glazed window of the same size and shape. You can reduce the heat loss further by using different glass types (such as low-E glass) or by choosing units which use argon gas to fill the space between the two panes of glass.

This table compares the performance of some glass and frame options.


Single glazing

Standard double glazing

Double glazing with low-E glass

Double glazing with low-E glass plus argon gas

Aluminium framesR0.15R0.25R0.31R0.32
Thermally broken aluminium framesR0.17R0.31R0.39R0.41
Timber / uPVCR0.19R0.36R0.47R0.50

Double glazing also helps to reduce condensation by keeping the house warmer.

Double glazing and noise reduction

Double glazing can also help to reduce noise levels, particularly in the medium to high frequency range (including voices). However, double glazing on its own won’t filter out loud or low-frequency noise such as that from traffic.

More effective noise reduction can be achieved by using thicker glass or by using laminated glass (some laminated glass comes with a thick acoustic inter-layer). The gap between the panes can also be increased for more effective noise insulation, but this reduces the effectiveness of double glazing as a heat insulator.