Understanding the changes to Part L Building Regulations

As a builder or developer, you’ve likely heard of Building Regulations Part L. Last year, there were changes you may not have heard of, or perhaps need more information on. With a grace period that ended in June this year, there’s still time to brush up on your knowledge and ensure compliance.

What are Building Regulations Part L?

Building Regulations Part L cover the conservation of fuel and power in the building of new homes and extensions in England. 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%.

Part L contains four documents, each of which focuses on different aspects of construction. Approved Document L Volume 1 contains Part L1A is for new homes, which is now assessed under the SAP10 calculation procedure (formally SAP 2012) and will set greater requirements on insulation. Part L1B is for extensions and renovations with some exceptions to the requirements.

Approved Document L Volume 2 contains Part L2A is for commercial buildings, while part L2B is for 'other' buildings.

Why are they important?

The adjustments to Part L are viewed as a steppingstone towards the 75–80% reduction in carbon, which will be required by the Future Homes Standard in 2025.

The regulations have been introduced to help create greater energy efficiency and savings on energy costs, as well as better environmental sustainability and stronger compliance.

If companies do not adhere to Part L regulations they face possible consequences, which can include stop work orders, fines, legal action and potentially damage to reputation.

Part L key takeaways

Reducing carbon and ensuring energy efficiency over the entire lifespan of a building features significantly as part of the new building regulations in the UK. 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:

  • New carbon emission target - All new homes must produce at least 31% less carbon emissions. New non-domestic builds need to produce at least 27% less.

  • New energy efficiency standard - U-values need to be improved in walls and replacement thermal elements from 0.28W/m2K to 0.18W/m2K, and the minimum values for doors, windows and roof windows has improved from 1.6 to 1.4.

  • SAP10 replaces SAP 2012 - SAP10 is responsible for setting and calculating the metrics and targets detailed above as well as other standards in building work.

  • 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.

When does Part L come into effect?

Part L (volumes 1 and 2) came into effect on 15 June 2022. The recent grace period also finished on 15 June 2023 for buildings currently still in the planning process. All new homes are now assessed under the SAP10 calculation procedure. As of now, your construction firm must be compliant with Part L.

How to stay compliant with Part L

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

  1. Provide your Energy Performance Certificate (EPC) assessor with the drawings and specifications of the build in full detail.
  2. Include Approved Construction Details (ACDs) as part of the design. These are large-scale section details of elements like window openings and eaves details.
  3. Once the design meets requirement L1A, the design assessment and SAP calculations are submitted to building control before work starts on site.
  4. If any changes are needed once construction begins, they should be notified to the SAP assessor during the build to ensure it remains compliant.
  5. Take detailed photos of all the required items and make sure it includes the Geo-location data to form part of the audit.
  6. As completion approaches, an air pressure test is carried out and the photo report is given to the SAP assessor, including declarations of the ACDs used during the build
  7. The assessor produces the as-built SAP calculations and lodges an EPC against the new home’s postal address.
  8. As-built SAP calculations and EPC are submitted to the building control body.

What do I need to know now?

Part L (volumes 1 and 2) came into effect on 15 June 2022, however a grace period takes effect until 15 June 2023 for buildings currently still in the planning process.Under the updated regulations, new homes are now assessed under the SAP10 calculation procedure, with a greater focus on the audit of the installation. Those involved in the construction are required to take photographs of the install to confirm that design details have been followed. Photos should also have geo location information available to verify they are of the correct plot.

How Fonn can help with Part L compliance

The 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.

If you want to find out more about Building Regulations Part L and how to remain compliant, we’ve produced an in-depth guide.

Part L Report


For more information on how Fonn can help with Part L, read our Part L compliance page or download our Part L compliance guide.

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