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Single Vs. Double Vs. Triple Glazing: Heat Loss & U-Values


Warm air moves towards cold glass and a typical house loses 10% of its heat via the windows. This expensive loss of energy can be combatted by investing in the right type of glazing for your home, in order to boost your property’s thermal efficiency.

Single Vs. Double Vs. Triple Glazing

Single Glazing

Conduction occurs easily with single glazing, as there is only one layer of glass between the inside air and outside air, allowing energy to escape more readily.  


Double Glazing

Double glazing is the installation of two sheets of glass, with spacer bars fixed around the edge to keep the panes apart. Between the two glass sheets is a layer of insulated air; this air space is often is filled with an inert gas such as argon.


Triple Glazing

Triple glazing is the installation of three sheets of glass, with spacer bars positioned around the edge. Again, between each sheet is a layer of insulative air.


These insulative layers of air found in double and triple glazing slow down convection and conduction between the warmer indoor pane and the cooler outdoor pane. As a result, heat energy escapes your home more slowly, keeping your house warmer for longer.


Thermal transmittance can be expressed as the U-value. Simply put, the higher the U-value, the more heat a window loses. Generally, the U-values are;

  • Single glazing: 5
  • Double glazing: 3
  • Triple glazing: 0.8 – 1.6

One technique of assessing the energy efficiency of your window is to see if it arrives with a rating from the BFRC (British Fenestration Rating Council). Windows and doors are assessed on a number of factors, and graded with a letter A ++ – E, with Building Regulations now requiring all homes to have C graded windows.

How Much Money can I Save with Double Glazing or Triple Glazing?


Double or triple glazing must be viewed as an investment that will reap rewards in the future by reducing the money you spend on your energy bills and also boosting the value of your property when it comes time to sell up.

Both the costs and savings caused by double glazing and triple glazing will be influenced by many other factors, such as; the size of your property, the size of your windows and other insulation measures in your home.

  • You could save between £50 – £175 on your energy bills per year by installing double glazing, as it is able to reduce window heat loss by 74%.
  • Triple glazing has been estimated to reduce energy bills by up to 50%.

This, coupled with other benefits such as noise reduction, security enhancement, and reduction of carbon footprint, makes double glazing and triple glazing well worth the investment. To get a better sense of how much you could save, check out this glazing energy saving calculator.

Ready to Fit your New Windows?

Don’t be ambitious and try and fit your own windows. Even if you fancy your hand at DIY, problems can arise if a window is improperly fitted, such as condensation problems or security issues.

Call in the professionals to guarantee you get the best results. Abbey Glass are Sheffield’s premier glass cutters and installers, with over 40 years of experience in the industry. We are able to cut, install and replace single glazing, double glazing and triple glazing to top industry standards. For your free quotation, get in touch with our friendly staff today.

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