Manufactured to meet UK building standards

Broxwood’s energy efficient timber windows and doors are designed and manufactured in Latvia where extreme winter conditions are the norm with temperatures dipping between -30° and -40°.

Due to their extreme winter climate, Latvian building standards are much more demanding than the those in the UK. As a result, manufacturers in Scandinavia and Latvia are continually developing newer, more thermally enhanced products to achieve amongst the best U-values anywhere in the world.

UK building standards


Visit the Scottish Building Standards website

In Scotland, building standards in relation to windows and doors are a little more stringent than those in England and Wales. Part J of the Scottish building regulations demands the installation of energy efficient double or triple glazing for all replacement windows with a U-value of 1.8 W/m2K or better.

For a deeper understanding of the rules surrounding energy efficiency you can find more information in the Scottish Buildings Standards Technical Handbook for Domestic Properties

England & Wales

Windows and Doors must comply with Part L of the Building Regulations.

New Build Projects

To determine the U-value required for windows and doors, the Whole Building CO2 Target Emission Rate (TER) must be determined using notional values. The Dwelling Emission Rate (DER) is then determined using actual values and must not exceed the TER. Only with these figures can the U-value for windows and doors be reached. The Building Regulations limit the maximum acceptable whole U-value to 2.2 W/m2K.

Window, roof window, roof light

New build extensions

  • Whole Window U-value 1.8W/m2K or better.
  • Centre pane U-value 1.2W/m2K or better.
  • WER ‘D’ rating.


  • Whole Window 2.0W/m2K or better.
  • Centre Pane U-value 1.2W/m2K or better.
  • WER ‘E’ rating.

Doors with 50%+ internal glazed face area

New build extensions

  • U-value 2.2W/m2K


  • U-value 2.2W/m2K or better.
  • Centre Pane U-value 1.2W/m2K or better.

Other doors

New build extensions

  • 0W/m2K