Existing Non-Dwellings

Existing Non-Dwellings

Redhouse old town hall
The Government has launched a consultation concerning changes to the Building Regulations in England for existing buildings other than dwellings.  These changes are expected to have a significant impact on glass and glazing products in buildings.

Ending on 13th April 2021, the consultation set outs proposed changes to Part L (conservation of fuel and power) of the Building Regulations for existing non-dwellings in England.  This follows on from last year's consultation on new dwellings, the Government's response to which has been published.

The table below summarises the limiting U values for new elements in extensions to existing buildings other than dwellings and new or replacement elements in existing buildings other than dwellings:
Maximum U value
Windows in buildings similar to dwellings*
WER Band B or better, or
U value 1.6 W/m2K
All other windows, roof windows and curtain walling
U value 1.6 W/m2K
U value 2.2 W/m2K
Pedestrian doors (including glazed doors)
U value of 1.4 W/m2K
*for example, student accommodation and care homes

WER, Window Energy Rating, is generally considered a better indicator of the energy performance of a window in an existing dwelling 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 should be based on the outer developed surface area, which is often greater than the area of the roof opening.  Unlike for windows and roof windows, rooflights should have their U values calculated based on a horizontal position.

No maximum U value has been set for display windows and similar glazing for existing buildings.

The proposals include an alternative if windows or fully glazed external pedestrian doors cannot meet the above requirements because of the need to maintain the character of the building.  In such cases, 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.

Where the effects of overheating in summer need to be mitigated, Pilkington provides a range of solar control glass for reducing solar gains in buildings, while maintaining high levels of daylight.

If you have any questions on Part L 2021 and what the implications might be for glass, please complete our online contact form, selecting 'Architect' or 'Trade' as the Enquiry Type and 'Part L 2021' as the Nature of Your Enquiry.