Energy Ratings for Windows
In recent years, new windows have been given energy ratings that help you make sure if the product you are having installed is suitable for our home. There are also other values you may well come across in conversation with your installer and certificates to look out for such as the CE Markings which confirm your windows meet current EU standards.
BFRC Energy Ratings
In line with other energy efficient projects, windows now have their own ratings system that stretches from A down to G, the former being the most efficient and the latter the least. New windows should have at least a C rating which covers the whole structure including the glass and the frame.
Cost and Different Rated Windows
Where you might find a big difference between ratings is in the cost of A vs C rated windows. Higher rated windows have a premium cost and are often touted by companies as bringing greater savings on fuel bills because they are more efficient. If you are swapping from a single glazed window to a double one then you would expect to save between £120 and £160 a year for A rated ones and between £110 and £135 for C rated. Over the lifetime of the windows, it may not make a big savings difference compared to the additional price you have to pay for the windows in the first place.
In other words, it could make sense to opt for lower C rated windows at a significantly lower price if you want better value for money.
Other Factors for Windows and Double Glazing
Energy rating gives you a good idea of how efficient your new windows are but there also a few other values and factors that you might come across as you explore different types of product. All relating to the type of glass you have installed, here’s our quick guide to what these terms mean:
R Value: This is the resistance to heat flow through a given material. The higher the R value, the better a material is at insulating.
U Factor: This is a measure of how much heat is lost through a given material and is the opposite of the R Value in that the lower the value the better the material is at insulating.
In other words: A window with a high R value and low U factor is more thermally efficient.
Solar Heat Gain Coefficient (SHGC): Calculated between 0 and 1, this measures the amount of incident solar radiation that passes through a particular window. The lower the SHGC, the less solar radiation comes through. This is more important for south facing windows that have access to more sunlight.
Visible Light Transmittance: This is the amount of light visible to the human eye that passes through a window and, as with SHGC, it is measured as a value between 0 and 1, with a higher value passing more visible light.
European Standards: CE Markings
Most manufactured products like windows and doors should have a CE marking which means that they comply with European safety and manufacturing standards. These are not a way for suppliers to make their product stand out from the competition, they are mandatory for anyone supplying a product in the EU. If you come across a product that does not have a CE marking then you should not have it installed on your property.
Another way that manufacturers try to set themselves apart from the competition is incorporating a British Standards Institute (BSI) kitemark. This certification goes over and above the CE marking and is a recognition of quality. Installers too can obtain a kitemark to cover areas such as their business practice and customer care so it’s worth checking if your chosen company has this on their literature.
Find out more about the BSI.