Existing dwellings in Wales

Existing dwellings in Wales

Pilkington Thermal Efficiency glass

The Welsh government has initiated a consultation concerning changes to the Welsh Building Regulations for existing dwellings. These changes are expected to have a significant impact on glass and glazing products in residential buildings.

Ending on 17th February 2021, the consultation set outs proposed changes to Part L (conservation of fuel and power) of the Building Regulations for existing dwellings in Wales. This follows on from an earlier consultation on new dwellings, the responses of which are currently being reviewed. Ventilation and mitigating overheating in new dwellings are also included in the same consultation.

For replacement windows, doors and rooflights in existing dwellings, the following standards have been proposed:

Controlled fitting Standard
Window or roof window
WER Band B or better, or
U value 1.4 W/m2K
Rooflights U value 2.2 W/m2K
Doors (including glazed doors)
Door Set Energy Rating (DSER) TBC*, or
U value of 1.4 W/m2K

*The appropriate DSER is to be confirmed to align with an overall U value of 1.4 W/m2K

WER, Window Energy Rating, is generally considered a better indicator of the energy performance of a window because it considers a range of parameters, including the useful solar heat gain. The U value is the total U value of the window, taking into account both the glass and frame.

The U value of a rooflight is based on total heat loss through the product divided by the total surface area of the rooflight.

The proposals include an alternative in the case of dwellings of architectural and historical interest where special considerations apply or there is a need to maintain the character of a façade.  If the windows or doors are unable to achieve the above U values in such dwellings, they should achieve or better a centre pane U value of 1.2 W/m2K or be upgraded to low emissivity (low-e) secondary glazing.

To satisfy the above requirements, Pilkington provides a range of low-e glass that can provide thermal insulation.

A further consultation covering non-domestic buildings in Wales will be held in 2021.

Documents related to the consultation on proposed requirements for existing dwellings can be found here.

If you have any questions on Part L 2021 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.