New Dwellings

New Dwellings

What is Part L 2021?

Ahead of the introduction of the Future Home Standard in 2025, changes to the regulatory requirements for the energy efficiency of new dwellings from 2022 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 dwellings in England.

The 2021 edition of Approved Document L Volume 1 has introduced 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 2.0 to 1.6 W/m2K.  The new limiting U-values for fenestration elements in new dwellings are provided in the table below.

Fenestration element
Maximum U-value (W/m2K)
Windows (including roof windows and curtain walling)
1.6
Rooflights (in horizontal position)
2.2
Doors (including glazed doors)
1.6

However, the expectation is that the U-value will have to be much lower than the above to enable a new dwelling to achieve its targets for primary energy, carbon dioxide emissions and fabric energy efficiency rates.  This is highlighted in the notional specification for new dwellings which includes the following reference U-values for fenestration elements:

Fenestration element
Reference U-value for target setting (W/m2K)
Opaque doors (less than 30% glazed area)
1.0
Semi-glazed doors (30 - 60% glazed area)
1.0
Windows and glazed doors with greater than 60% glazed area
1.2
Roof windows
1.2
Rooflights (in horizontal position)
1.7

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

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.

We value your privacy.

We use cookies on this website for analytics, remarketing, social media (optional) and content (essential) purposes.

By clicking ‘Accept All’ you consent to the use of cookies for non-essential functions and the related processing of personal data. Alternatively you can reject non-essential cookies by clicking ‘Essential Only’. You can adjust your preferences at any time by visiting our Cookie Policy and access the settings on that page.

For more information please read our Cookie Policy.