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Energy Efficiency

About the BFRC (British Fenestration Rating Council) Labels

The BFRC label clearly indicates the rating of the designated window or door (A++ to E) depending on the energy efficiency levels achieved by the manufacturer. A++ is the most energy efficient, E the least efficient. 

The level of energy efficiency is indicated by one of a range of coloured bars - very similar to the energy efficiency labels found on fridges, freezers, washing machines and other household products.

During the rating process the energy efficiency level is verified by BFRC, which is totally independent from any manufacturing or installing company. Manufacturers of BFRC rated product and BFRC Authorised Installers are audited to ensure that their energy efficient windows and doors are achieving the stated rating.

The BFRC energy ratings allow you to compare varying window and door products and choose the most suitable for your home. 

You can view the BFRC ratings for products sold through Andy Glass Windows on the BFRC website or ask one of our sales team for more information and help.

Energy Window BFRC

u-Value (Thermal insulation)

u-Values measure how effective a material is as an insulator. The lower the U-value, the less heat is lost and the more insulation the material providesThis measurement is usually quoted for the sealed glass units in windows although it also applies to other building materials.  
u Values are expressed as Watts per square meter, per degree Kelvin (W/m2K)

g-Value (Solar heat gain)

This identifies the percentage of solar heat that can pass through a window.  The higher the percentage the more solar heat passes in through the window helping to warm your house at no additional cost. Solar heat gain (g value), can be difficult to control, for example on a southern elevation you can receive solar heat gains all day, this means that the area can easily over heat, architects normally specify solar control glass that reduces solar heat gain on highly exposed elevations like the south face.

Air leakage

This simply measures the air penetration through the window.  Most modern casement windows will score a zero air leakage in this area meaning no drafts from air penetration.


What Is The Difference Between Detailed and Simplified BFRC Energy Licences?

A ​detailed energy licence is specific to one particular window.  As the components are known the rating label can display the energy index,

u-value, g-value and air leakage.

The ​simplified energy licence can be applied to a collection of windows that all have the same frame and rating band but might have different component parts e.g. the glass.  Only the rating band is common, u-values and g-values could vary and therefore cannot be stated on the energy rating label.

Which Type of Low Emissivity Glass Is Best?

The low emissivity coating (low-e) determines how much heat is lost through the glass.  As the performance of the low-e improves the solar gain values decreases.  As the BFRC rating is an energy balance between heat losses and solar energy gains, the best performing low-e glass are not necessarily best for energy ratings.

Do Triple Glazed Windows Give Better Energy Ratings?

Not necessarily.  Windows with triple glazed units can give lower glass (centre pane) u values, however this is very much dependent upon the types of glass used. Often the additional third pane of glass will reduce the solar gain significantly. It is possible to achieve the BFRC A+ rating using double glazed windows.

Do Trickle Vents Effect The Window Energy Rating?

Energy ratings for windows and doors are to be used as a comparison between two or more similar products.  Window and doors ratings are calculated without trickle ventilators, as any detrimental effect introduced by the ventilator would be the same across all products being compared.

E.g. when considering the difference between an A rated window and a B rated window, the introduction of a trickle ventilator would result in the A rated product still out performing the B rated.

The same logic is applied to Georgian bars and leaded lights.

Who Calculates The Energy Rating?

BFRC energy ratings are calculated by BFRC Certified Simulators. Simulators are trained and continuously assessed to ensure that the ratings produced are consistent. All ratings submitted by BFRC Simulators are verified by BFRC to ensure accuracy.

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