Energy-Efficient Windows: Energy Ratings Explained

We all know that our homes should be more energy efficient but knowing how to translate energy ratings into practical purchasing decisions can be a confusing process. With winter rapidly approaching, many homeowners have been left wondering how they can best prepare their homes for the colder months ahead – while futureproofing their property to reduce their carbon footprint. With the average UK home losing 25-30 per cent¹ of its heat through windows, installing energy efficient windows and double glazing can help make a big difference to the warmth and security of a property – and help save the planet too. So, how can you find out how energy efficient your windows are?

Launched in 2004 by an independent government supported body, Window Energy Ratings (WER) were established to develop and administer a system of UK energy ratings focussed solely on windows. The aim of the scheme was to make it easier for homeowners to understand how energy efficient their windows are and highlight how effective modern double glazing can be.

Using a colourful, rainbow inspired design, which has been widely adopted on energy labels for popular home appliances, such as refrigerators and washing machines, the labels provide an easy way to see how different window products compare when it comes to their energy efficiency.

The labels use an easy-to-read, traffic light system which includes a letter and colour band ranging from A++ to E. Just like your school grades, the higher the letter in the alphabet, the better your window is at doing its job. An A++ rated window is therefore far more energy efficient than a window with an E rating. Letter ratings are given to windows based on their thermal efficiency, air leakage and solar gain, and take into consideration the whole window, including the frame material, glass type, shape and design – as well as other components. As you would expect, the highest window rating is more likely to cost more, however while this may be a higher outgoing in the short-term, it is guaranteed to have long-term cost-effective benefits.

¹ Research found by Energy Saver, 2021

Since October 2010, government legislation outlines that all new windows must have a minimum Window Energy Rating of band C – which is handy to know if you’re currently house hunting and looking at properties older than 2010. It’s also worth noting that this legislation does not apply to windows fitted in listed buildings, so if you’re looking for a rural retreat or period property, remember to consider other ways to safeguard your property from losing its energy. We would advise always asking the homeowner for any paperwork regarding the windows from the point of installation, regardless of how old the property is, and ensuring you budget for a thorough home inspection of the overall property, as this will provide a better overview of its energy efficiency.

It’s important to remember that Window Energy Ratings only provide an indication of the level of efficiency offered by the window product itself. The amount of potential energy saved once the window is installed in your home will be dependent on other factors, such as where the window is located, the efficiency of your heating system and any other insulation in your home.

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A Guide to Window Energy Ratings