Automatic U-Value calculator designed for bespoke joinery. Windows, sliding sash, doors, and screens – 3 instant calculations for an item as you design.

Why waste money testing your product's U-values at a testing facility, only to spend even more if changes are needed? Use our automatic U-value calculator to instantly determine the U-value of any window, sliding sash, door, or screen as you design them.

All manufacturers in the UK are required to provide whole-item U-values for external windows and doors, not just centre-pane values. Our calculator performs three instant calculations as you design.

The U-value calculator within JMS simplifies compliance with Building Regulations by calculating the whole-item U-value of your joinery product. It considers the timber type, section size, overall size, spacer bar, and materials used – all in real-time.

Without JMS, you may need to spend significant amounts testing individual units to obtain U-values. With JMS, this information is available instantly at no extra cost* with just a click of a button.

JMS also provides printed reports detailing how the U-value was calculated and generates U-value certificates. These certificates serve as proof of compliance for your customers, offering a cost-effective alternative to testing each individual window or door.

U-values are displayed during the design stage, allowing you to check compliance and advise your customers on necessary changes to improve performance.

JMS calculates three values:

• The model window U-value (based on a 1230x1480 window).
• The exact item's U-value at the model size.
• The calculated U-value.

This gives you flexibility in selecting the best U-value, as all options are accepted for compliance with Building Regulations.

*Note: A valid maintenance and support contract is required to access U-values.