How do I know what U values I need for my home?

How do I know what U values I need for my home?

Different regulations apply across England, Scotland, Wales and Northern Ireland.

Generally, for new builds the building designer or building regulations / planning approval will determine what value is required for your windows and doors for your project.

For replacement windows – a maximum U value of 1.6 or a BFRC window energy rating of C is allowed.