SAP & EPC Calculations
Design & As Built Calculations for L1A & L1B.
  • Guaranteed maximum 5 day turnaround
  • 24 hour turnaround available
  • Unlimited reviews to specification
  • Assessors will always be on hand
  • Low cost for multiple plots

The Standard Assessment Procedure (SAP) are calculations required at design stage for all planning applications in order to generate the final SAP reports and EPC (Energy Performance Certificate) to demonstrate compliance with current Part L building regulations for England & Wales. The report itself is designed to measure the energy performance of new build dwellings as well as refurbishment and conversions providing simple to read information on its energy usage to the occupant/s in the form of the EPC. We thrive to offer a thorough design package allowing you to ensure compliance is achieved upon completion of the project. This includes free consultation and changes to specifications from design stage through to the final as built SAP & EPC. 

BREW Compliance - SAP Caluclations, SAP Assessments, EPC, Energy Performance Certificates, Design SAP, As Built SAP, Predicted EPC, Part L Compliance

Single Plot

Available From

SAP Reports undertaken at the design stage of your project, while offering advice on achieving Part L compliance for the project if necessary. 

Our price for a SAP assessment always 

includes the design stage SAP, predicted energy performance assessment PEA and the final As Built SAP and EPC.


With no extra hidden fees.


Unlimited reviews to the fabric should you consider alternative fabric, heating or renewable options throughout  the design phase. Available From £150

Wooden House - Multiple SAP Assessments,

Multi Plot

Available From

Multiple plots on one site can be a stressful job for those involved. We can take control of compliance from design stage SAP assessments down to managing the on site air tightness 

testing & schedule and producing the final As Built SAP & EPC following the air test.

From as little as £35

For larger projects of houses or flats please contact us for quotation.

BREW Compliance - SAP Caluclations, SAP Assessments, EPC, Energy Performance Certificates, Design SAP, As Built SAP, Predicted EPC, Part L Compliance



Please contact us for a quotation on commercial SBEM/BRUKL reports.

What is a SAP and EPC assessment?

A SAP assessment calculates various parameters but the most important being the TER (Target Co2 Emission Rate) and DER (Dwelling Co2 Emission Rate), TFEE (Target Fabric Energy Efficiency) and DFEE (Dwelling Fabric Energy Efficiency). The designed dwelling must match or better these targets generated by the SAP software or in some cases the DER must exceed the TER by a 25% reduction for example. 

The SAP assessment also calculates a figure ranging from 1 – 100+ with energy bands A-G assigned and reflected on the EPC (Energy Performance Certificate) as seen in the example rating graph here. The rating provided by the SAP assessment denotes the energy efficiency of the building that has been assessed; the higher the rating, the more energy efficient the building is according to the SAP. The assessment must be provided by an appropriately qualified and accredited OCDEA professional, who will use the latest approved SAP software to calculate various energy expenditure elements of the building or development.

L1A SAP Assessment?

Part of the SAP assessment also involves calculating the U-values and ensuring these also meet the minimum standards outlined in Part L1A & L1B regulations. New build projects must conform to the minimum U-values in L1A, however it's now pretty much become standard practice that designs exceed these u-values substantially in order to achieve compliance for both the DER (Dwelling Co2 Emission Rate) and DFEE (Dwelling Fabric Energy Efficiency) within the SAP compliance report. Other parameters such as overheating, glazing, water cylinders and more must also meet minimum requirements and show as compliant as illustrated in an example here. This is what makes design stage SAPs so important in order to ensure compliance at the final stage of completion. Any changes to fabric or heating plans must be re-run in the SAP software to ensure compliance will be achieved. 

L1B SAP Assessment?

For L1B regulations. Conversion and renovation projects must conform to the minimum U-values outlined in L1B, however these values need not be exceeded to achieve compliance for the DER (Dwelling Co2 Emission Rate) and DFEE (Dwelling Fabric Energy Efficiency) within the SAP compliance report and only all other parameters must pass from section 2 onward as illustrated in an example here. 

We can help advise you on the most cost effective solutions to bring your existing elements in-line with L1B regulations by modelling any retained elements such as a solid brick wall within a U-value calculator. While there are no strict pass or fail criteria for conversions other than minimum

u-values it's worth bearing in mind that if you plan on renting the property then you must meet a minimum rating of E on the Energy Performance Certificate (EPC). 

Over Glazed Extension SAP (Glazing greater than 25% of floor area)

Building Regulations require that the glazing in a new extension does not exceed 25% of the floor area so a SAP Calc will usually be required by Building Control if you are proposing to build an extension with a large amount of glazing to demonstrate compliance with Part L1B.

The work required for over glazed extensions is double that of a new build or conversion, as two SAP calculations are required.

Existing Dwelling plus a 'Notional' extension - This will show the dwelling as it stands plus an extension that has a glazing area that is only 25% of the floor area. The External Walls, Floor and Roof will show the minimum requirements to meet building regulations.

Existing Dwelling (with any necessary improvements) plus the 'proposed' extension - This will show the existing dwelling with any improvements plus the extension based on the proposed specifications. The external walls, floor, and roof, glazing and heating system are likely to be an improvement on that of the assumptions in the 'Notional' extension. 


The idea of carrying out the notional and proposed calculations is to show that the C02 emissions of the Dwelling plus the 'actual' extension are no higher than the C02 emissions of the dwelling plus the 'notional' extension. If this isn't the case for your proposed extension one of our experienced SAP assessors will be on hand to guide and work with you through possible solutions. 

Please enquire via our quotation form.