Submit details to U Value Calculator

Accurate u-values for windows and doors

Our U Value Calculator gives accurate u-values for windows and doors. Our certificate with unique serial number should be acceptable to planning departments. The certificate will be issued in PDF format on receipt of full payment.
Note: We cannot guarantee that your planning department will accept this certificate. But none has yet refused them.

The cost of this service is £35 per certificate.
Payment by bank transfer to
Account Number 00109860
Sort Code 80-17-68
Reference Your Company Name.

Alternatively you can now pay by paypal using button below:



Calculator for Windows and Doors

timber framed wood windows


All measurements are to be specified in mm
L1 and W1 are the dimensions of the Frame.
L2 and W2 are dimensions of first glass panel, if there are more than one glass panel continue filling in the boxes. L3 and W3 are for the second panel and so on. We also need the thickness of the frame.

Glazing Types

The glass types specified on our form are manufactured by "Saint Gobain".

If your glass is supplied by any other manufacturer please specify the details in the appropriate box with the u-value of that glass, which you can obtain from your supplier.

Type of Sealant used

We will assume foam. However if something else is being used please feel free to specify what it is..