New Non-Dwellings

New Non-Dwellings (England)

Part L

Ahead of the introduction of the Future Building Standard in 2025, changes to the regulatory requirements for the energy efficiency of new buildings other than dwellings are expected to have an impact upon glass and glazing products.

Published on 15th December 2021 and coming into force on 15th June 2022, the government has set out its new requirements for Part L (conservation of fuel and power) of the Building Regulations and the supporting Approved Document for new non-dwellings in England.

There are no specific values for individual building elements, but a new building must be shown to meet or better the target primary energy and carbon dioxide emission rates for a notional building of the same size and shape as an actual building with standardised properties for fabric and services.

The 2021 edition of Approved Document L Volume 2 has made changes to the limiting elemental standards for fabric performance – sometimes referred to as 'backstop' values – including a reduction (improvement) in the window U-value from 2.2 to 1.6 W/m2K.  The new limiting U-values for fenestration elements in new buildings other than dwellings are provided in the table below.

Element
Maximum U-value (W/m2K)
Windows in buildings similar to dwellings*
1.6 or minimum WER Band B
All other windows, roof windows and curtain walling
1.6
Rooflights
2.2
Pedestrian doors (including glazed doors)
1.6
*for example, student accommodation and care homes

For external fire doorsets, a maximum U-value of 1.8 W/m2K is permissible.

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.  However, the impact of display windows must be taken into account in the calculation of primary energy and CO2 emissions for the new building.

Pilkington manufactures a range of low emissivity glass for thermal insulation that can help windows, doors and curtain walling to achieve low U-values.

The proposals also include requirements to limit the effects of solar gains in summer when compared with reference glazing systems.  Pilkington provides a range of solar control glass for reducing solar gains in buildings, while maintaining high levels of daylight.

The 2021 editions of Approved Document L Volumes 1 and 2 can be downloaded from here.

If you have any questions on the new regulatory requirements 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' as the Nature of Your Enquiry.

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