Window Energy Ratings Explained

22nd June, 2022

Window Energy Ratings (WER) and U Values for windows are handy ways to calculate how energy efficient your windows are. The Energy Ratings scale goes from A++ to E and tends to be the more modern way to calculate energy efficiency. U Values, however, are a more traditional method which measures heat loss and the rate at which it is lost at in Watts per square metre Kelvin, or W/m2 k.

Window energy ratings explained

Window Energy Ratings

Window energy ratings are a great tool to tell you how energy efficient your windows are. The efficiency of your windows is measured by The Window Energy Rating (WER); the rating system scales from G, worst performance, to A++ for the best performance, determining how energy-efficient your windows are.

Even though A+ rated windows provide a better thermal performance, it does help to weigh up the options when choosing which windows best suit your needs, taking into account factors such as budget. This alongside how warm your home tends to be and the condition of your current windows should help you choose which windows are the best for you. In addition to this, our very own energy saving calculator ensures more energy efficiency which in turn helps you to save energy sustainably.

Window energy ratings explained
British Fenestration Rating
Council WER Scheme
Window energy ratings explained
Certass Thermal Rating
Register Scheme

Benefits of Energy Rated Windows

There are various benefits of having energy-rated windows, for yourself and your home. Luckily, as of October 2010, legislation demands that all windows must have a minimum Window Energy Rating of band C to be installed; this means that all windows will have some degree of efficiency.

But how efficient?
A-rated double glazing, and above, offers a more comfortable home with fewer draughts and cold spots. Furthermore, as well as keeping the heat in, windows with the best energy rating will provide peace and quiet from the hustle and bustle outside. Various other benefits are to be enjoyed, such as reduced condensation and limited risk of dampness and mould.

Window energy ratings explained

U Values for Windows

The typical U-Values for windows measure heat loss, showing how efficient a window is at retaining its warmth. Generally, the lower the U-Value double glazing the better; as with WERs building regulations have recently changed, meaning that double glazing U values must be below 1.6 W/m2k. Although both U Values and Window Energy Ratings are recognized forms of measuring energy efficiency, the latter is typically more popular.

L Values

L Values work to figure out how much air escapes from your windows on a whole including the glass and frame, thus determining how airtight it is. The lower the L value, the less air that escapes; this means more heat is kept inside your home. It is typically understood that the optimum L value for windows should be 0.

If you're interested in new windows today, look no further than our swap shop which provides an opportunity to get up to £100 for each old window and door towards new ones.

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