True Windows


With the introduction of Energy rating on buildings and the new building code regulations, this is an area that is currently receiving alot of interest from our clients.

The energy rating or U-Value of a window or door is a combination of the U-values of the glass package and the frame.

There are two methods of calculating this;

1. BS EN 10077-2 Thermal Performance of Windows, Doors and Shutters – Calculation of Thermal Transmittance – Numerical Calculation. This method uses a computer programme to calculate the transmittance of the various elements and combines these into a single U-Value for the overall item.

2. BS EN 12567-1 . This method is a hot box of an actual window or door. The test item is an average sized window (width 1230mm and height 1480mm).

Our permanent manufacturing partner has undertaken this test on our behalf with a sample standard double glazed window and we have received a certification for a U-Value of 1.4W/(m2K). Follow the link to see the certificate.

Should you wish to achieve a U-Value lower than this there are a whole range of options available. It is important to look at the overall insulation on your building when considering these. Please feel free to call our office to discuss your options further.