u-value calculator for bespoke Windows and Doors

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U-Values for Windows and Doors - Suitable for bespoke manufacturers

If you a small manufacturer / builder / architect who needs a u-value for a window or door we can help. Our U-value calculator gives accurate u-values for bespoke designed windows and doors that are made from all types of wood or even composite materials.

Our calculated value conforms to Part 1 of BS EN ISO 10077 in regard to the Thermal performance of windows, doors and shutters. Our calculation provides customers with the information they require to comply with Building Regulations.

All we charge for our service is £35. This fee includes a certificate with the stated u-value of the window or door.
No membership is required. You can use our service as little or as often as you like.

Inexpensive Calculator for small manufacturers

Getting an accurate u-value for a bespoke manufactured window or door can be extremely expensive for small independent manufacturers. We provide that solution and you do not need to pay any additional membership fees either.

A u-value obtained from us should be sufficient to satisfy the requirements of Building Regulations. Please note that our calculation is based on Part 1 of the standard only. It cannot be used as the basis for obtaining a full BFRC Window Energy Rating (WER). WER requires a u-value that complies with Part 2 of BS EN ISO 10077. We do not offer such a service.

Wood or Composite frames

Our calculator works for doors or windows. They can be made from either hardwood, softwood or accoya, they can be of any size fitted with double or triple glazing. If you can provide us with the u value of any other type of composite frame you are using we can provide a u value for that too.

Our uvalue calculator is not restricted to products manufactured by one company.

Simple 3 Step Process

Submit Details

Simple to Use

Fill in the boxes on our form. Specify the frame size, type of wood, spacer, the type of glass and size of the panels. We then calculate the U Value of your product and send you a certificate which specifies the u value of your product. This certificate can be used as formal support when you supply U-value information to potential customers or Building Control.


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