Buildings other than dwellings

Buildings other than dwellings

Changes to Part L of the Building Regulations in Wales, including the supporting Approved Documents, are expected to have a significant impact on glass and glazing products in residential and non-residential buildings. High performance, energy efficient glass and windows are expected to play a crucial role in delivering nearly zero energy buildings (nZEB) in the UK.

Through its Stage 2B consultation ending on 17th January 2022, the Welsh Government has set out its proposed changes to Part L (conservation of fuel and power) and Part F (ventilation) of the Building Regulations for non-domestic buildings. The consultation also covers the future direction of building energy policy in 2025.

The consultation on proposed changes for buildings other than dwellings in Wales are anticipated in accordance with the following timeline:

Estimated date
October 2021 Stage 2B consultation on Parts L and F for non-domestic buildings
Early 2022 Stage 2B consultation response
Spring 2022 Publication of Approved Documents
Autumn 2022 Part L and Part F for non-domestic buildings enter into force

Although new buildings are required to achieve a minimum energy performance, limiting U values – sometimes referred to as 'back stop' U values – are set for some building elements to prevent poor fabric design. The following limiting U values for fenestration elements have been proposed for new non-domestic buildings:

Element Maximum U value (W/m2K)
Windows 1.6
Roof windows, curtain walling
Rooflights 2.2
Pedestrian doors (including glazed doors)

Dependent upon the project design, the U values may have to be lower than the above values to enable new buildings to achieve the whole building minimum energy performance target.

Proposed limiting U values for new and replacement fenestration elements in existing non-domestic buildings are provided in the table below:

Maximum U value (W/m2K)
Buildings essentially domestic in character
All other buildings
Windows 1.4 or Window Energy Rating band B
Roof windows, curtain walling
1.8 1.8
Rooflights 2.2 2.2
Pedestrian doors (including glazed doors)
1.8 1.8

If windows or fully glazed pedestrian doors are unable to meet the above requirements in an existing building, in order to maintain the character of the building, either of the following should apply:

  • the maximum centre pane U value should be 1.2 W/m2K, or
  • single glazing should be supplemented with low emissivity secondary glazing

Documents related to the consultation on the proposed requirements for non-domestic buildings can be found here.

If you have any questions on Part L 2022 in Wales and what the implications might be for glass, please complete our online contact form, selecting 'Architect' or 'Trade' as the Nature of Enquiry and 'Part L' as the Enquiry Type.

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