A guide to Windows

How do double and triple-glazed windows work?

  • Energy ratings explained
  • Strong panes separated by a layer of safe gas
  • Extra insulation with triple glazing
  • Secondary glazing to improve existing windows

Installing double-glazed windows is vital when it comes to retaining as much heat as possible in your home, but how exactly do they work?

We're going to take a look at the science behind our double and triple glazing to help you understand exactly why double and triple-glazed windows are worth investing in.

Energy ratings explained

You might have noticed that all windows have an energy rating. This rating takes three factors into consideration. Deciding on an energy rating involves measuring thermal transmittance (how well your windows retain heat), the amount of air leakage and the window's ability to absorb the sun's energy.

Windows are rated from 'E' to 'A++', with 'A++' rated windows performing the best.

A window with a rating of 'B' or below loses more energy than it creates, and this is why all of our double and triple-glazed windows have an energy rating of 'A' or higher.

Strong panes separated by a layer of safe gas

Double-glazed windows are created with two panes of glass, each separated by a vacuum of gas called a sealed unit. Argon gas is purposely used here, as it has a thermal conductivity of around 67%, making it a poor conductor of heat. Unable to transfer heat well, the gas reduces heat loss by preventing warmth escaping the home through the second layer of glass.

Compared to A-rated double glazing, single glazing can lose up to 20% of your home's heat. Choosing to install double glazing can dramatically cut down the cost of your energy bills, and you'll notice the extra layer of glass helps to cut out draughts and reduce unwanted noise too

Extra insulation with triple glazing

Triple glazing uses three panes of glass to deliver maximum heat retention, with two Low E glass panes and one Low Iron pane. There's an invisible metal coating on each Low E pane which helps the glass to reflect heat back into the home.

Between each pane of glass, you'll find a thermally optimised spacer bar designed to stop heat escaping around the edges of the unit. Krypton gas fills the space between each pane of glass, which then helps to prevent heat from escaping the home.

Anglian secondary glazing

Secondary glazing to improve existing windows

The third and final type of replacement glazing is secondary glazing. Secondary glazing provides a solution for homes that are unable to install double or triple glazing, and can be particularly useful for homeowners who are restricted by planning permissions.

Secondary glazing improves the energy efficiency of existing windows in a subtle way. A second pane of glass is added, fitting easily over the existing window, to improve heat retention and sound insulation. The subtle and slim sliding units can work for a wide range of window styles and sizes, and they are virtually undetectable.