How Much Do SAP Calculations Cost? A Guide to Prices and Quotes

Indicative SAP calculation prices

Our current indicative base prices are:

These categories are intended as a guide to the scale of work involved.

Small extension: £150

A simple domestic extension with straightforward construction.

Larger extension or small conversion: £225

A larger extension, loft conversion or relatively straightforward alteration to an existing house.

New-build house: £295

A typical detached, semi-detached or terraced new dwelling.

Larger or more detailed house: £350

A larger house with more varied construction, glazing arrangements or building services.

Large bespoke home: £450

A substantial house with several construction types, extensive glazing or more complicated heating and ventilation arrangements.

Large or complex residential project: £450+

A particularly large or complicated property, potentially including multiple wings, an annexe, detached garage, varied construction and extensive openings.

All prices are indicative. The final quotation depends on the assessment required, the complexity of the project and the information available.

For a more interactive guide, visit our SAP Calculation Cost & Prices page, where you can select the project category closest to your own.

Indicative pricing last reviewed: October 2026.

What affects the cost of SAP calculations?

Although project size is a useful starting point, the amount of assessment work depends on several factors.

1. Type of building project

Different projects can require different types of energy assessment.

New-build houses

New dwellings normally require design-stage energy calculations and subsequently an as-built assessment. The final documentation may also include a new-build Energy Performance Certificate (EPC).

Extensions

Not every extension requires a full SAP calculation. However, calculations may be necessary or useful where an alternative method of demonstrating Part L compliance is appropriate, particularly for designs with extensive glazing.

Conversions

Converting an existing building into residential accommodation can introduce additional complexities, particularly where retained walls, floors and roofs need to be assessed alongside new construction.

Retrospective assessments

Where calculations are requested after building work has been completed, additional investigation may be required to establish what was actually constructed.

2. Size and complexity

A larger property can require more calculation work, but floor area alone doesn't determine the cost.

Complex features may include:

• Several different wall, roof or floor constructions
• Unusual roof shapes or changes in floor level
• Extensive glazing or multiple opening types
• Different heating and ventilation systems
• Complex building geometry
• Heated spaces adjoining garages, annexes or other unheated areas

A relatively compact building with complicated construction can require more detailed modelling than a larger building with a simple design.

3. Number of dwellings

For developments containing several houses or flats, the number of dwellings and different designs influences the assessment requirements.

Some information can be reused across similar dwellings, but individual properties may still require separate calculations due to differences in geometry, orientation or heat-loss conditions.

For multiple dwellings, we'll normally review the development and provide an appropriate quotation rather than assuming that a single-house indicative price applies to every unit.

4. Stage of construction

A design-stage SAP calculation assesses the proposed building.

An as-built calculation reflects what was actually constructed, incorporating the final specifications and relevant supporting evidence.

Your quotation should identify whether the required work covers the design stage, as-built stage or both.

Changes to the specification during construction can also result in further assessment work.

5. Available drawings and specifications

Accurate architectural drawings and construction specifications can make the assessment process more straightforward.

These normally include floor plans, elevations, sections, insulation details, glazing information and heating and ventilation specifications.

Missing information doesn't prevent you from requesting a quote, but it may mean that additional clarification is required.

For further guidance, read our article What Information Do You Need for a SAP Calculation?

What is included in a SAP calculation quote?

Our indicative base price includes the core work involved in preparing a SAP assessment.

SAP assessment

Reviewing the information supplied and completing the SAP calculation using the relevant methodology and software.

Review of your drawings

Reviewing suitable plans, elevations, sections and specifications to obtain the information needed for the assessment.

Standard turnaround

Our normal completion timescale is approximately 8–10 working days once we have everything needed to begin.

The quotation will confirm the scope of work and any additional requirements before proceeding.

Are there any additional costs?

Most straightforward projects may only need the base assessment, but some require additional work.

Our current additional charges are:

Additional U-value calculations

Where a required wall, roof or floor U-value hasn't already been calculated or adequately documented, we may need to prepare a separate calculation to support the SAP assessment.

This is currently priced at an additional £50 where required.

Priority turnaround

If you need your calculation sooner, a priority service may be available.

Our current additional charge is £50, with a target turnaround of within five working days where availability permits and all required information has been supplied.

Additional technical work

Unusual construction, missing technical information or calculations beyond the normal assessment scope may sometimes require additional work.

Where this applies, we'll explain the requirement and confirm the cost before proceeding.

There should be no unexpected additional charges. Any work outside the agreed base assessment will be discussed and quoted before it is undertaken.

Are design-stage and as-built SAP calculations priced separately?

They can be, depending on the agreed quotation.

The design-stage assessment is based on the proposed construction and building services.

The as-built assessment is completed using the final construction details, installed systems and any necessary test or commissioning information.

Some projects require both stages, while others may only need a particular assessment or update.

It's important to check the scope of your quotation, including whether an EPC is required and included.

What happens if your SAP calculation doesn't comply?

A SAP assessment may identify that the proposed design doesn't satisfy the applicable energy performance requirements.

This doesn't necessarily mean that the project needs a complete redesign.

Sometimes changes to insulation, glazing, heating, airtightness or renewable energy provision can improve the result.

Where amendments are required, the amount of additional assessment work will depend on the changes involved and the terms of the original quotation.

For more information, see our guide Common Reasons a SAP Assessment Can Fail.

Can you get cheaper SAP calculations online?

Submitting your project information online can make the enquiry and quotation process more efficient.

However, a professional SAP assessment still requires appropriate technical modelling and compliance checks.

When comparing quotations, consider more than the initial advertised price.

Check:

• Which assessment stages are included
• Whether the required reports are supplied
• Whether an EPC is included, if needed
• How design changes and revisions are handled
• Whether additional U-value calculations are required
• The quoted turnaround time
• Whether the assessment covers the particular work you are undertaking

A lower headline price may not represent the lowest overall cost if additional services are required later.

How can you keep SAP calculation costs under control?

There are several practical steps that can help reduce unnecessary work and delays.

Start the assessment early. Potential compliance issues are generally easier to address during the design stage than after construction.

Provide current architectural drawings. Clear plans, elevations and sections help the assessor establish the building's geometry.

Include the construction specification. Insulation, glazing, heating and ventilation details can help avoid repeated requests for information.

Explain the project type clearly. State whether the assessment concerns a new build, extension, conversion or completed building.

Confirm the assessment scope. Check which stages, reports and additional services are included.

Communicate design changes. Updated specifications may affect the calculation and should be reviewed before the final assessment is completed.

How do you get an accurate SAP calculation quote?

Our online enquiry process guides you through the information needed to assess your project.

It helps to have:

• The project address or postcode
• The type of building work
• The number of dwellings, where relevant
• The current project stage
• Any architectural drawings available
• Details of the proposed construction and building services
• Any previous SAP reports or Building Control correspondence
• Your required timescale

You don't need to have every technical detail ready before getting started.

Once you've provided the project information, we can review the requirements and confirm the quotation.

Frequently asked questions

How much does a SAP calculation cost for a new-build house?

Our indicative base price for a typical new-build house is £295. The final quotation will depend on the building's complexity, available information and assessment requirements.

How much do SAP calculations cost for an extension?

Our indicative price starts at £150 for a small, straightforward extension, increasing to £225 for a larger extension or small conversion. Not every extension requires SAP calculations, so the appropriate assessment will depend on the work proposed.

How much does a SAP calculation cost for a large bespoke house?

Our indicative prices are £350 for a larger or more detailed house and £450 for a large bespoke home. Particularly large or complex residential projects start from £450 and are reviewed individually.

Are U-value calculations included in the price?

Where the necessary U-values are already provided or adequately documented, separate calculations may not be required. Additional U-value calculations are currently charged at £50 where needed.

How quickly can I get SAP calculations?

Standard turnaround is normally 8–10 working days once all necessary information has been received. A priority option may be available for an additional £50, with a target of within five working days.

Can I request a quotation without drawings?

Yes. You can submit an initial enquiry without drawings, although they help establish the scope of work and may be needed before a firm quotation can be confirmed.