What is ‘A’ rated Glass

Whether you are a domestic customer or trade customer you may have heard the term ‘A Rated Glass’ but are you aware that there is no such thing?

This term is becoming frequently used in the uPVC industry to describe a glass specification that will allow a window to achieve an ‘A’ rating. The actual glass specification used is:- 4mm Clear Float – 20mm Argon Gas Filled Spacer (90%) with Swiss V (or similar) Thermal Spacer Bar – 4mm Low-e (softcoat). This glass make-up achieves a centre pane u-value of 1.2 W/m2K.

In 90% of uPVC systems this glass allows the window to achieve an A Rating hence why it is being referred to as ‘A Rated Glass’. Unfortunately, it does not achieve an A rating when Glazed into an Aluminium Window and it is becoming more and more confusing for the end customer and trade alike. The Window Energy Rating (WER) system applies only to windows as a whole and not to its specific components i.e. glass or frames.

Using the same glass specification in one of our Alitherm 47 windows (for example) would achieve a ‘C’ Rating. Although this is still fully compliant with current regulations, it may not be what the customer is expecting.

OK… so how do I achieve an ‘A’ rated Window using Aluminium?

This is completely possible but it is not as easy as you may think. Because of the many different sections available, we have to calculate the glass requirement on a job by job basis.

In order to make this process as easy as possible we need to be told of specific energy requirements at the quotation stage. If you require an ‘A’ rated Window please state this on your enquiry and we can allow the correct glass specification to achieve this.

If you are a trade customer and are supplying your own glass to suit our windows you will need to be fully aware of what glass specification is required. If you require assistance with this calculation please contact us.