What is a BREL report?
- SAP calculations for domestic buildings
- SBEM calculations for non-domestic buildings
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When is a BREL report required?
BREL reports are required for:
- New build dwellings
- New non-domestic buildings
- Residential and commercial conversions
- Change of use projects
- Some extensions assessed under Part L1A
BREL documentation is required at design stage and as-built stage for Building Control approval.
Is a BREL report required for all extensions?
No. Most extensions to existing dwellings are assessed under Part L1B and do not require a BREL report. However, a BREL report is required where:
- A new self-contained dwelling is created
- The extension is part of a material change of use
- The project is assessed under Part L1A
- Building Control specifically requests SAP / BREL evidence
What is the difference between SAP and BREL?
- SAP is the calculation methodology used to assess the energy performance of domestic buildings.
- BREL is the compliance report generated from SAP (or SBEM) results to demonstrate Part L compliance.
In simple terms:SAP produces the data – BREL presents it in a format Building Control accepts.
What is the difference between SBEM and BREL?
- SBEM is the calculation method used for non-domestic buildings.
- BREL is the compliance output generated from SBEM calculations.
Both SAP and SBEM feed into BREL documentation depending on building type.
Do I need both design stage and as-built BREL reports?
Yes. Building Regulations require:
- Design stage BREL – based on proposed drawings and specifications
- As-built BREL – based on what has actually been constructed
Both are required for Building Control sign-off. A design stage pass alone is not sufficient.
What happens if a building fails a BREL assessment?
If a building fails to meet Part L targets:
- The areas of non-compliance are identified
- Practical recommendations are provided
- The design or specification can be adjusted
Common solutions include:
- Improved insulation
- More efficient heating systems
- Better glazing performance
- Targeted renewable technologies
How long does a BREL report take?
Typical turnaround times are:
- Design stage: 2–5 working days
- As-built stage: 1–3 working days once final data is received
Timescales may vary depending on project complexity and information availability.
What information is needed to produce a BREL report?
Information typically required includes:
- Architectural drawings
- Construction build-ups
- Heating and hot water details
- Ventilation strategy
- Lighting details (non-domestic)
- Air tightness test results (as-built stage)
Any missing information is identified early to avoid delays.
Are BREL reports accepted by all Building Control bodies?
Yes. BREL reports produced using approved software and methodologies are accepted by:
- Local authority Building Control
- Approved inspectors
Reports must reflect the actual design and construction to be valid.
Does a BREL report include an EPC?
No — but it provides the data needed to produce one.
Once the as-built BREL is complete:
- Domestic EPCs are generated from SAP
- Non-domestic EPCs are generated from SBEM
EPCs are usually issued alongside final compliance documentation.
Do BREL reports cover air tightness?
BREL reports include air tightness results where testing is required.
The air permeability value:
- Is entered into SAP or SBEM
- Directly affects Part L compliance
- Must match the test certificate
Poor air test results can cause a previously compliant design to fail at as-built stage.
Are BREL reports required for commercial buildings?
Yes. Non-domestic buildings require:
- SBEM calculations
- Non-domestic BREL documentation
- Non-domestic EPCs
These are required for both new builds and certain extensions or conversions.
Can BREL reports be produced remotely?
Yes. BREL reports are typically produced using:
- Digital drawings
- Specifications
- Test data
Site visits are not usually required unless combined with testing services.
Who is responsible for providing the BREL report?
The responsibility typically sits with:
- The developer
- The main contractor
- The property owner
However, coordination with architects and designers is common to ensure accuracy.
How does Part O (Overheating) affect BREL?
Part O is a separate regulation covering overheating risk in residential buildings. While Part O assessments are separate from BREL, design changes made to reduce overheating can affect:
- SAP calculations
- Part L compliance
- BREL outcomes
A coordinated approach avoids conflicts between regulations.
What regulations do BREL reports relate to?
BREL reports primarily relate to:
- Building Regulations Part L
They also link to:
- Part F (ventilation)
- Part G (water efficiency)
- Part O (overheating)
Accurate data across all regulations is essential for compliance.
What happens if information changes during construction?
If changes occur on site:
- Calculations are updated
- BREL reports are revised
- ·Compliance is reassessed
Keeping reports up to date avoids delays at completion.
Do conversions always require BREL reports?
Most conversions that create new dwellings or involve a material change of use do require SAP and BREL documentation.
Each project should be assessed individually to confirm the correct compliance route.
Can BREL reports be fast-tracked?
Yes, where information is available.
Urgent BREL reports can often be produced within 24–48 hours, subject to project complexity.
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