At SAP Assessors, we provide accredited SAP (Standard Assessment Procedure) calculations, tailored compliance reports, and Energy Performance Certificates (EPCs) for residential projects at both design and as-built stages.

Since changes to energy targets and carbon reduction make early-stage planning more complex, our assessors help you model different options to meet compliance in the UK.

As errors or delays in SAP reporting can hold up approval, we offer a fast, expert service with clear recommendations from start to finish.

Request your free SAP assessment quote today.

What Does a SAP Assessor Do?

A SAP assessor collects detailed information about the building’s structure and services, including floor plans, insulation values, heating and hot water systems, windows, lighting, and any renewable technologies.

They input this data into government-approved software to model the building’s energy performance and generate two key documents: the SAP Report and the Energy Performance Certificate (EPC).

If the building is at the design stage, the assessor produces a predicted energy assessment to support planning or Building Control approval. 

Once construction is complete, they update the model with actual specifications and issue the as-built SAP report, the EPC, and (for new-builds) the BREL report.

As SAP assessors provide evidence for compliance with Part L, their role is essential from pre-construction through to final approval.

What Is the Difference Between a SAP Assessment and an EPC?

A SAP assessment is the calculation process used to determine a property’s energy performance during design and construction. 

The EPC (Energy Performance Certificate) is the official document issued at completion, showing the property’s energy rating. The SAP assessment generates the data used to produce the EPC.

How Much Does a SAP Assessment Cost?

The cost of SAP assessment is from £150 to £350 per dwelling.

The cost depends on the size of the property, the number of units, and whether additional documents like the BREL report or thermal modelling are needed.

For larger developments or phased builds, discounts may be available.

Since the SAP report is a legal requirement, this service is a standard part of any residential construction budget.

When Is a SAP Assessor Required?

SAP assessors are required for all new residential dwellings in England and for many conversions or change-of-use projects where thermal elements or building services are altered.

The assessor must be engaged before construction begins to support design-stage compliance, and again after completion to verify the final energy performance.

Since SAP results determine whether your project can proceed or be signed off, their involvement is necessary at both ends of the build process.

What Is Included in a SAP Assessment?

A full SAP assessment includes the following:

The SAP assessor collects construction details and builds a digital model of the property.

The model calculates the dwelling’s predicted energy use and carbon emissions.

The SAP assessment determines compliance with Building Regulations Part L.

Outputs include the SAP reports, EPC, and, where applicable, a BREL report.

The assessment considers wall, roof, and floor insulation, thermal bridging, glazing performance, heating and hot water systems, ventilation type, and any low-carbon technologies.

As these elements affect your property’s carbon rating and heating demand, accurate input is essential for valid results.

What Are the Benefits of Using a SAP Assessor?

A qualified SAP assessor helps ensure your project meets energy efficiency regulations and avoids unnecessary delays.

Key benefits include:

• Confirms compliance with Building Regulations Part L
• Produces all required documents for planning and Building Control
• Advises on design changes to improve energy performance and reduce emissions
• Supports the generation of EPCs for property sales or lettings
• Helps avoid costly redesigns or compliance failures after construction
• Offers bundled services including BREL reports and overheating assessments
• Works with developers, architects, contractors, and self-builders

How Long Does a SAP Assessment Take?

Design-stage SAP assessments are usually completed within 2 to 5 working days.

The timeframe of the SAP assessment depends on the completeness of the information provided.

As-built SAPs and EPCs can be issued within 2 to 3 days once all final test results and specifications are submitted.

Since energy documentation is required before sign-off, early submission of documents ensures a smoother approval process.

What Is the Difference Between a SAP and an EPC?

The SAP report is a technical document that models a dwelling’s energy use and carbon emissions to check compliance with Building Regulations Part L.

The EPC, or Energy Performance Certificate, is a summary document based on the SAP results that provides an energy efficiency rating for the property.

As the EPC is derived from the SAP data, both must be completed for new residential properties.

Do I Need a SAP Assessment for a Conversion or Renovation?

If your project involves converting a building into residential use or significantly upgrading thermal elements or services, a SAP assessment is likely required.

Conversions typically fall under Part L1B, but still require SAP calculations to confirm compliance and generate the EPC.

As older buildings may have complex fabric upgrades, early assessment helps identify what improvements are needed.

Can You Produce SAP Assessments for Flats and Multi-Unit Developments?

We regularly carry out SAP assessments for apartment blocks, terraces, and large housing schemes.

Each unit is modelled individually, and common areas such as stairwells or corridors are assessed based on shared service layouts.

Since multi-unit projects often involve repeated designs, we offer discounted rates for grouped assessments.

What If My Design Doesn’t Pass the SAP Calculation?

If the initial SAP calculation shows non-compliance, we’ll provide clear advice on how to improve the design.

This may involve upgrading insulation, selecting more efficient heating systems, improving glazing, or adjusting the layout.

As SAP is a flexible tool, we work with your design team to achieve compliance without unnecessary cost or delay.

Is It Better to Use the Same SAP Assessor for Design and As-Built Stages?

Using the same assessor ensures consistency, avoids data loss, and speeds up the final reporting process.

Your assessor will already be familiar with the project and can verify changes more easily when updating to the as-built stage.

Since Part L compliance depends on both design and completion documents, working with a single provider is the most efficient approach.

Do You Offer Overheating Assessments or BREL Reports?

We offer a full range of supporting services, including Part O overheating assessments, BREL reports, and compliance coordination.

Since these documents are often needed alongside SAP and EPCs, we provide bundled packages for faster turnaround and lower costs.

This ensures your entire compliance process is handled smoothly, from start to finish.

What Information Does a SAP Assessor Need?

A SAP assessor will require architectural drawings (floor plans, elevations, sections), construction details (insulation specs, U-values), heating and hot water system specifications, ventilation details, and information on any renewable technologies being installed. 

The more detailed the information provided, the smoother the assessment process.

Can I Use the Same SAP Assessor for Design and Completion Stages?

It is common and recommended to use the same SAP assessor throughout the project. 

This ensures consistency, easier tracking of changes, and quicker processing of the final EPC once construction is complete.

What Happens If My Design Fails the SAP Assessment?

If a design does not meet the required energy efficiency standards, the SAP assessor will provide recommendations to improve performance. 

Recommendations may involve increasing insulation levels, upgrading heating systems, improving glazing specifications, or incorporating renewable energy solutions to achieve compliance.

Do SAP Assessors Cover Commercial Buildings?

SAP assessments apply only to residential properties. 

For commercial buildings, energy assessments are conducted using SBEM (Simplified Building Energy Model) calculations, which are handled by different types of qualified assessors.

How Do I Get Started with SAP Assessors?

For fast, accurate SAP assessments and full energy compliance support, contact SAP Assessors. 

As energy performance standards are strict and time-sensitive, early and expert input from a SAP assessor can save time, money, and stress.

Get your tailored quote today.

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