The Window Energy Rating (WER) tells you how energy-efficient your windows are. The rating system is based on a scale of G to A+, with A+ windows being the most energy-efficient.
Considering up to 25% of the heat within most homes escapes through the windows, checking their energy rating is as important as any other energy saving measure around the home. More and more people are opting for A or A+ rated windows.
Window Energy Ratings were originally launched in March 2004 by the British Fenestration Rating Council (BFRC), an independent government-supported body established to develop and administer a system of Window Energy Ratings in the UK. The BFRC is run by the Glass & Glazing Federation (GGF) the trade body representing many window companies.
Since then both BSI and Certass have set up similar schemes and window companies can gain approval and register with any of these.
What is a Window Energy Rating?
A window’s rating is determined by a formula which takes into account the total solar heat transmittance, the amount of the sun’s heat which can pass through the glass (usually referred to as g-value); the U-value of the whole window (frame and glass combined), how well the window keeps the heat in your home; and the air infiltration through the window seals. To make the Rating standard across all products, a standard window size and configuration is used. The resulting value is then placed into a band on the scale G-A, with A-rated windows being the most energy-efficient. This makes the system of rating windows consistent with other products which have energy performance labels such as those that will be familiar on washing machines, light bulbs and refrigerators.