How have June’s Changes to Part L Effected Window Specification?

How have June’s Changes to Part L Effected Window Specification?

On the 15th June 2022, interim changes to building regulations came into force as a step towards The Future Homes and Building Standard. NorDan’s Commercial Sales Manager Sonia Travis examines what these changes mean for window specification.

How have June’s Changes to Part L Effected Window Specification?
Sonia Travis – NorDan

The first tranche of changes to building regulations came into force in England on the 15th June as an interim, incremental uplift in advance of The Buildings and Homes Standard legislation being introduced and implemented 2025.

The government said June’s changes would achieve a balance between making progress towards the Future Homes Standard, while providing the industry ‘with the time it needs to develop the supply chains and skills that will be necessary and accounting for market factors’.

What has changed?

The updated regulations include amendments to Approved Documents Part F (Ventilation) and Part L (Conservation or fuel and power), and the release of a new Approved Document for Overheating (Part O) and Infrastructure for Charging electric vehicles (Part S).

Here I will be focusing on Part L as this is the regulation that has the most significant impact on window specification.

Who and what is effected?

The changes to Part L affect new and existing homes and non-domestic buildings.

Part L1A covers the requirements for new homes to be energy efficient, and individuals responsible for building work must ensure that the homes comply with the requirements provided within this document

Part L1B covers the requirements for renovations and extensions to existing homes to be energy efficient. It recognises that it is not always possible to meet new build standards, but the regulations state that if a thermal element is being replaced or renovated then it must be done to Part L1A standard.

Finally, Part L2A covers the required energy standards during construction of new non-domestic buildings, and Approved Document L2B covers existing buildings other than dwellings.

Why are these changes happening?

The Department for Levelling Up, Housing & Communities says: “(The changes) mark an important step on our journey towards a cleaner, greener built environment and it supports us in our target to reduce the UK’s carbon emissions to net-zero by 2050”.

These are some of the measures being taken to reduce all greenhouse gas emissions to meet the legally binding 2050 UK deadline, and the aim is to reduce the corban emissions generated by home built post June by up to 80%.

How do the changes affect windows and doors?

The new regulations have changed maximum allowable u-values, and so are relevant to the specification of windows and doors.

U-values are a measure of heat loss through a material, and they are used to measure how effective a building’s fabric is as an insulator. The lower the u-value, the less heat is being transferred from inside to outside the building.

Building Regulations Part L covers the u-values of new windows and doors. For new windows installed in existing buildings properties.

The acceptable u-value was 1.4 W/m²K, but has now been lowered to 1.2 W/m²K to comply with the energy efficiency requirements of new build homes.

Replacement and new build windows will be subject to the change in u-values and will help meet the 31% reduction in CO2 emissions required for all new homes.

How have June’s Changes to Part L Effected Window Specification?

Good news for timber

A materials U-value refers to its Thermal Conductivity or Thermal Resistance. This is the rate that heat will conduct through one metre of a material.

Materials that heat up quickly will have a high U-value, but different materials transfer heat at varying speeds.

Timber is a naturally insulating material with an organic cell structure that contains tiny air pockets that act as a barrier to heat and cold.

This allows timber frames to achieve a u-value of 1.2 using just double glazing – hitting 0.74 when triple glazed.

In short, Part L has handed timber window and doors a competitive advantage over other materials, as PVCu, Aluminium and composite windows can usually only achieve a u-value of 1.2 when accompanied by triple glazed.

This increase in the cost and carbon impact of additional glazing has forced many window manufacturers to recalibrate the design and cost of products to meet customer requirements.

NorDan’s windows and doors on the other hand have always met the standards set out by Part L and always exceed British Standards for weather performance.

NorDan double-glazed windows remain the best-in-class, easily meeting Part L, as well as the further predicted increases in standards in 2025.

Finally, if anyone requires any advice on the impact of changing building regulations on windows and doors then please contact our expert specification team via NorDan’s UK website.

Sonia Travis is the Commercial Sales Manager for the North of England at NorDan UK Ltd. For more information on their high-performance timber windows please visit their website