Whole Window U Value Calculator

Calculator for Windows and Doors

Our U Value Calculator is designed to calculate the accurate u-value of bespoke design windows and doors. It can be a single paned window/door, or one with a number of panes of glass.

Whole Window U Values

This is a whole window calculator that works out the combined u value of the glazing, the frame and the spacer. We do not just supply a u-value taken from the centre point of the glass or the centre of a window panel.

u-value for timber framed wood window and doors

Why you now require u-values

From October 2010 building regulations in Great Britain specified that all new doors would have to adhere to a door u-value rating of 1.8W/m2K or less. Windows in new dwellings would have to have a u-value rating of 2.0W/m2K or less and replacement windows would have to have a u-value rating of 1.6W/m2K, or have a minimum WER rating of Band C.

Our calculator is designed to easily calculate the u-value of windows and doors to see if they comply with these regulations.  Our calculator does not restrict you to using products from any specific manufacturer. nor do you not need to be a member of our site or download any additional software.

We can calculate the u value of single, double or triple glazed windows built with softwood, hardwood or accoya frames. If you can provide the u-value for any upvc frame then we can work out a u-value for that too.

We can make adjustments for window and doors with or without spacers and any thermal bridges used in the installation.

No Membership Required

You do not need to be a member of our website to make use of our calculator. It is open to use by anyone. You can use it as often or as little as you want. From one window to a thousand. Contact us for discounted rates where several windows are involved.

Conforms to European Standard EN ISO 10077

Our U Value Calculator will provide you with a calculation that is performed in accordance with the U-Value equation provided in European Standard EN ISO 10077 part 1 Thermal performance of windows, doors and shutters. It will provide an accurate u-value that will satisfy your building control.

U Value Certificate

On submitting the required details to us and on receipt of the necessary payment, we will calculate your U-value and send you a certificate with a unique serial number for that window or door. You can then use that certificate to demonstrate compliance with Building Regulations (depending on the U-values that were obtained).