Part L Building Regulations Explained: Changes & Compliance 

Part L of the Building Regulations covers the conservation of fuel and power in new and existing buildings in England, including new homes and extensions. They establish how energy-efficient they should be. On June 15, 2022, Part L was updated with the mandate to improve the current minimum standard for carbon emissions by 31% - this was previously just 6%, so the increase is a significant one. From 24 March 2027, Part L is renamed "Energy and greenhouse gas emissions" and also requires reasonable provision to minimise greenhouse gas emissions. 

There are two volumes in Part L:  

• Volume 1 

For new and existing homes. 

• Volume 2 

Reducing carbon and ensuring energy efficiency over the entire lifespan of a building features significantly as part of the new building regulations in England. This can be achieved in several ways, such as maximising airtightness, optimising insulation and eliminating thermal bridging. 

Other takeaways to look out for in the Part L changes include:

• Geotagged photos

Builders and developers are required to take photographs of the install to confirm the design details have been followed. Not only that, but photos should also have geo location information available to verify they are of the correct plot.

• New carbon emission target

All new homes must produce around 31% less carbon emissions on average. New non-domestic builds need to produce around 27% less. 

• New energy efficiency standard

For new or replacement walls in existing homes, U-values need to be improved from 0.28W/m2K to 0.18W/m2K, and the limiting values for replacement doors, windows and roof windows have improved from 1.6 to 1.4. 

• SAP 10.2 replaces SAP 2012 

SAP 10.2 is responsible for setting and calculating the metrics and targets detailed above as well as other standards in building work. Under Part L 2026, SAP 10.3 takes over. 

Part L doesn't just set a target on paper. It changes how projects are designed, priced, built and handed over. 

Energy decisions move to the start of design 

Under Part L 2026, new homes need low-carbon heating and, with limited exceptions, on-site renewable electricity. In practice, that means heat pumps and solar PV in most cases. These choices shape roof layouts, plant space and electrical capacity, so they need settling at design stage, not swapped in later. 

Costs need pricing correctly from tender 

Higher-performing fabric, heat pumps and solar PV all change the cost of a build. Pricing a scheme on old specifications, or missing which plots fall under which version of Part L, puts margin at risk before work starts. 

Programmes need room for evidence 

Photographic evidence has to be captured as each detail is finished, before it's covered up. If a photo is missed, work may need opening up again, or sign-off gets delayed while the gap is resolved. 

Transition timing affects every plot 

Transitional protection applies building by building, not site by site. On a large development, plots that don't start before 24 March 2028 lose transitional protection and must be built to the new standard. Start dates need planning plot by plot to avoid late redesigns. 

More people share responsibility 

Designers, site managers, subcontractors and energy assessors all contribute to Part L compliance. Under the Building Safety Act, clients, designers and contractors also have a legal duty to make sure the work complies (see below). 

Handover information matters more 

From 2027, information given to owners of new homes about ventilation, on-site electricity generation, overheating and fixed building services has to be provided in an appropriate format. 

Now! Part L (volumes 1 and 2) came into effect on 15 June 2022. The grace period also finished on 15 June 2023. It covered buildings where a building notice, initial notice or full plans were given before 15 June 2022, as long as work on that building started before 15 June 2023. All new homes are now assessed under the SAP 10.2 calculation procedure. As of now, your construction firm must be compliant with Part L, or face delays to projects which can lead to fines and other costs associated with project delays.  

Access Fonn has a dedicated solution that supports Part L compliance, without the need for additional tools to bring together the information that you need. 

When does Part L 2026 apply? 

Part L sets the energy standard a building has to meet. The Building Safety Act 2022 changes who is accountable for meeting it, and how that's checked. 

Dutyholders are responsible for Part L compliance 

 Since 1 October 2023, the dutyholder regime has applied to most building work in England, not just high-rise. Clients, principal designers and principal contractors must plan, manage and monitor work so it meets all relevant building regulations, and that includes Part L. Energy performance is no longer something to leave to the SAP assessor at the end of the job. 

Higher-risk buildings go through the Building Safety Regulator 

Higher-risk buildings are at least 18 metres or seven storeys tall and either have at least two residential units or are hospitals or care homes. For these, the Building Safety Regulator is the building control authority, and approval runs through a series of gateways. 

There are several steps you should take to be compliant with Building Regulations Part L:

1. Plan your schedule of works

Provide your EPC assessor with drawings and specifications of the build in full detail.

2. Capture information at every stage

Share your scope of works with your whole team, and notify your assessor of any changes.

3. Ensure your information has metadata and geotags embedded

Images that are not correctly tagged may be rejected by your SAP assessor.

4. Keep documentation available

Ideally, everything should be available in one location.

5. Access reports on-demand

SAP calculations and EPC are submitted to the building control body - everything should be kept together.

The Access Fonn app captures photos of the build and automatically geotags them for the SAP10 assessment. Our system produces a full report in PDF format, capturing all relevant details, dates and time stamps which will make any Part L assessment much easier, while providing full transparency to EPC assessor and end user.

Fonn has developed this feature alongside several well-known building companies. This ensures the platform is compliant and easy to use for the build team.