Energy services

Energy efficiency is a key part of building regulations compliance for new homes, conversions and extensions. Approved document L volume 1 sets the minimum standards for conserving fuel and power in dwellings, helping to ensure that homes are designed and built to perform efficiently.

As the UK moves towards net zero, these standards are becoming increasingly stringent. Getting the energy strategy right early can help avoid delays, redesign work and compliance issues later in the project.

The current standard is approved document L 2021 for England, using SAP 10.2. Approved document L 2026 and SAP 10.3 are due to come into force on 24 March 2027. Please see ‘The future homes standard’ tab for more details.

Our Energy Services Team provides on-construction SAP support for projects across Shropshire, England and Wales.

We stay up to date with the latest changes to domestic energy regulations and can support you with the services listed below. Further guidance on current and future regulatory requirements is also available.

New build (SAP/BREL/EPC, water and overheating)

All new-build dwellings require a SAP (standard assessment procedure) assessment with BREL report (Building Regulations England part L) (or BRWL for Wales – Building Regulations Wales part L). 

This is provided at the 'as designed' stage, and at the 'as built' stage along with the EPC. A compliant SAP/ BREL (or BRWL) demonstrates compliance with approved document L.   

Water calculations are also required to demonstrate compliance with approved document G (water efficiency).  

With the introduction of the latest regulations, all newly built properties also require an overheating calculation, which demonstrates compliance with approved document O (overheating). 

Our service includes:

  • As designed/as built EPC, including relevant U-value calculations and thermal bridging details 
  • Water calculations to demonstrate compliance with approved document G 
  • Overheating calculations – using the simplified method – to demonstrate compliance with approved document O. Note, we don't currently offer the thermal dynamic method.

Conversion (SAP/BREL/EPC and water)  

All conversions where a new unit of accommodation is being created also require a SAP at the 'as designed' and 'as built' stage, along with an EPC. A compliant SAP demonstrates compliance with approved document L.    

Water calculations are also required to demonstrate compliance with approved document G (water efficiency). 

Overheating calculations aren't required for conversions.  

Our service includes: 

  • As designed/as built EPC, including relevant U-value calculations 
  • Water calculations to demonstrate compliance with approved document G 

Extension (excessive glazing calculations)

Extensions to existing properties which are excessively glazed (glazing over 25% of the floor area), may also require an excessive glazing calculation. Compliance is demonstrated by one of two methods: 

  • Area weighted U-value 
  • Whole house SAP comparison 

Our service includes a calculation to demonstrate compliance using one of the above methods, with full U-value calculations. 

The Future Homes Standard

The Future Homes and Buildings Standards were published on 24 March 2026, alongside Approved Document L 2026 and updates to Approved Document F. They set the next step toward lower-carbon, more energy-efficient new buildings in England. The Welsh government has also published similar requirements.

What's changed?

  • Low-carbon heating is now central to compliance, with fossil fuel heating effectively eliminated as a route to compliance
  • Part L now gives greater emphasis to energy efficiency, reduced greenhouse gas emissions, fabric performance and commissioning
  • Solar PV is expected on most new homes, subject to any applicable (and likely very limited) exceptions
  • Approved Document F has been updated, with greater emphasis on effective ventilation, commissioning and homeowner information
  • SAP 10.3 is the initial compliance route, with the Home Energy Model intended to replace SAP in due course

Key implementation dates

  • 24 March 2026: Final standards published.
  • 24 March 2027: New requirements come into force for most building work in England.
  • 24 March 2028: Transitional protection ends for buildings other than higher-risk buildings (HRB’s), unless the application or notice was submitted before 24 March 2027 and the relevant work has been sufficiently commenced.
  • 24 September 2027: Relevant provisions come into force for higher-risk building work and work to existing higher-risk buildings.

FAQs

When do the new standards start?

Most new requirements apply from 24 March 2027. For non-HRB work, transitional protection generally requires submission before that date and sufficient commencement by 24 March 2028. HRB work has separate provisions from 24 September 2027.

Will it affect existing homes?

The main changes apply to new homes and new building work, although some guidance updates may affect certain work to existing homes.

Will solar panels be required?

Solar PV is expected on most new homes, subject to the detailed calculation, site constraints and any applicable exceptions.

What calculation method will be used?

SAP 10.3 is the initial compliance route. The Home Energy Model is still expected to replace SAP later.

Why is it important?

The standards aim to cut carbon emissions making new housing effectively ‘net-zero ready’, to reduce the need for future retrofit work.

Useful links

Current framework 

The 2021 regulation changes included the following: 

Changes to parts F (ventilation) and L (conservation of fuel and power), the introduction of overheating with approved document O, and provision for electric car charging with approved document S. 

The new SAP 10.2 framework is now used to demonstrate compliance with approved document L. It places greater emphasis on fabric efficiency, renewable technologies, zero-carbon heating, thermal bridging and more besides. 

Photographic evidence is now a requirement, and it's not possible to issue a compliant BREL report without the required photographic evidence. 

Part O was introduced to address the issues associated with well-insulated housing overheating in the summer. This looks at the amount of glazing based on the elevation, and the number of windows/doors that can open to remove excess heat. 

Useful links on current requirements concerning energy

Approved documents

Make an energy application/enquiry

Email our energy surveyors and they'll be happy to help.