Doors and Windows - How to comply with the Part L changes in 2022

Table 1: Timetable for the proposed changes to Part L

The new performance targets have been established with a focus on environmental and energy efficiency to deliver high-quality constructions that meet wider commitments and are future-proofed for the long-term.

Set out by the Department for Levelling-Up, Housing and Communities (DLUHCD) formerly the Ministry for Housing, Communities and Local Government (MHCLG), these announcements are steps towards the Future Homes and Building Standard, previously known as the Future Homes Standard (FHS), and are due to be implemented in 2025. This policy will require all new homes to be "zero carbon ready". Essentially, this means that the homes are properly equipped for the decarbonisation of the energy grid and would not need retrofitting.

These will demand homes and non-domestic buildings produce at least 75% less carbon emissions than the current Building Regulations allow. As a result, further changes are anticipated that could see U-values drop to levels now applied in Passivhaus standards. This will mean a big shift for the industry as in reality not much has changed since the infancy of U-values for minimum fabric values. 

WHAT ARE THE MAIN CHANGES TO PART L?

BASED ON DWELLING NOT THE WHOLE SITE

Going forward for domestic projects, the focus will be on the dwelling rather than the whole site, meaning that larger sites registered before June 2022 can build to the current version of Part L. However, any dwellings not started within one year will have to build to Part L 2021.

2021 / 22 PART L1 - 31% REDUCTION IN CO2 EMISSIONS

The changes show an interim uplift for 2021/22 that is expected to produce 31% less CO2 emissions for dwellings and 27% less CO2 emissions for non-dwellings compared to current standards. 

To achieve this, a standard specification has been created identifying fabric and building services used in the notional building, which is essentially a hypothetical building of the same size, shape, orientation and shading as the actual building. An indicative 2025 FHBS specification is also provided which shows the progression to a 75% uplift overall. 

Its the notional values that as an industry we should be pushing and aiming for. This will require a more engineered approach. 

To comply with the 2013 version of Part L, you must achieve a Dwelling Emission Rate or DER, no higher than the Target Emission Rate (TER) and a Dwelling Fabric Energy Efficiency (DFEE) no higher than the Target Fabric Energy Efficiency (TFEE). In the 2021 version of Part L there is a new form of compliance:

• DER no higher than the TER

AND

• Dwelling Primary Energy Rate (DPER) no higher than the Target Primary Energy Rate (TPER)

The replacement of a target fabric approach to primary energy one is DLUHCs change in emphasis. The focus will be on driving energy efficient decisions, which in some scenarios may not offer low-carbon solutions but the retention of TER should prevent this. 

To comply with current Part L legislation, developers, architects and fabricators should ideally be aware of the values, which form part of the TER / TFEE.

Fabric and building services limits contacined within Part L almost become irrelevant as the TER/TFEE reference values exceed them. For example, if a new dwelling has a window U-value of 1.6 W/m2K then it would meet the Part L limit (2.0W/m2K).

However, given it exceeds the 1.4W/m2K value used in the TER/TFEE, it means the shortfall created could have to be made up elsewhere. The same approach can be applied to any part of the specification i.e. if the proposed specification is worse than the TER/TFEE value the difference must be made up in another part of the specification. 

As a result, by reviewing the reference values it can be said that any new homes adopting the value set out in Table 2 will achieve compliance with 2013 Part L requirements.

*WER (Window Energy Rating)

DSER (Door Set Energy Rating)

HOW CAN SPECIFIERS AND FABRICATORS MEET THE NEW STANDARDS?

One option is to specify systems that are already capable of meeting the updated requirements like the new TECHNAL SOLEAL Next window and door suite of products, which are modelled around double glass to achieve the 2021 values. Recently unveiled by TECHNAL UK, the new aluminium window and door system, available later in 2022, will not only meet the new figures but will also allow for the move to 2025 figures in the future. 

This is because it's been designed as a modular system. SOLEAL Next introduces a tier system of performance to target the range present in the changes in Doc L from 1.6 up to 1.2w/m2k and beyond to a potential 0.8w/m2k for FHBS specification requirements. 

To lower carbon emissions during the use phase, SOLEAL Next is also extruded using Hydro CIRCAL® 75R – the prime-quality aluminium alloy that has a minimum content of 75% recycled post-consumer scrap from old windows, doors and facades to help lower CO2 emissions during the construction phase. Hydro CIRCAL® 75R has one of the smallest CO2 footprints worldwide: at 2.3kg of CO2 emissions per kilo of aluminium. This is 86% or 7 times less than the global average for primary extraction.

TECHNAL is also working to launch new products with an even higher content of recycled aluminium in the future. 

The new platformed SOLEAL Next range has been developed with circularity in mind. There has been careful consideration of the components used in the fabrication of the product to ease the dismantling process at the end of the buidlding's lifecycle. The thermal breaks are now made with 100% recycled material and no product used in the construction of SOLEAL Next contains PVC.

For fabricators too, there are many common items used across the platform variations, which apart from reducing waste, reduces the amount of stock articles, adding speed and simplicity for specification, fabrication and installation.

As well as the uplifts to Part L (fuel and power), there are also changes to Part F (ventilation) as well as the announcement of a new Approved Document O to mitigate the risk of overheating in new homes. TECHNAL will continue to assess the situation and assist our clients and other industry stakeholders with updates on the Part L changes.

If you need support meeting the updates Part L standards on your next project, use our form to contact us or contact your TECHNAL Account Manager, Project Consultant or Technical Representative.