East Acton Sap Assessors

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Sap Calculations, What Exactly Are They

If you are reading this, you’ve probably been recently requested by someone, usually your building control officer, to provide sap calculations for your building project.

You can click on the video on this page, where Andreas will shed some light on this, or continue reading.



East Acton SAP Calcs For Dwelling Change Of Use

  • Reports for Part L1B Compliance
  • Free Advice

East Acton SAP Calcs For Overglazed Extensions

  • Carbon Emissions Reports
  • Heat Loss Calculations
  • Free Advice

East Acton SAP Calcs For New Builds

  • Reports for Part L1A compliance
  • Free Advice

What does SAP mean?

SAP stands for Standard Assessment Procedure and it is the UK government’s method of determining the energy efficiency of dwellings. These calculations are needed to demonstrate that a building complies with specified energy targets laid down in the building regulations.

That’s pretty much it in a simple overview.


When Are SAP Calculations Needed?

Here are most of the reasons you may well be asked for sap calculations

1. For extensions that have more than the permitted amount of glazing
2. For all new homes
3. For a dwelling that’s changed its use, e.g converting a commercial building to domestic flats.

The two main areas that the sap calculations will look at is that the carbon emissions from your dwelling are within set tolerances and that certain components of the property, for example the roof, walls ,floors, and windows comply with specified thermal energy targets

A good set of building plans must be provided to the Assessor, as all the calculations are done from the building plans . Your Assessor will advise you of precisely what is needed. An EPC or Energy Performance Certificate can be produced after the computations are completed.

Your Assessor can provide additional advice if the calculation show your building isn’t compliant, as well as tell you which will be the most effective improvements to make. It’s very important to liaise with the Assessor as early on in your project as possible because when the building is completed any non-compliances could possibly be quite costly to rectify.

Should you require advice on a project you may have in , or require a quotation, contact us or fill in our get a quote form.


Need to have an answer to a query you have about SAP calculations in East Acton? The following are the ten most common questions.

Sap Calculations, What Exactly Are They

This is certainly by far the most frequent query asked. Check out Andrea’s video explanation above, or read the full explanation here on the right.

How Much Are Sap Calculations

This could differ considerably depending upon the size and complexity of the dwelling, however a standard cost range will be between £120 – £300. Should you also require an Energy Performance Certificate (EPC) at the end of it there could be another charge of around £50 to lodge the EPC on the epc register. Reductions would typically be available for multiple dwellings especially if they are of the identical form of design.

What Is The Difference Between Sap and EPC

Before we explain the difference, this is what you will require depending on your job.

For a new build property you’ll need – SAP calculations and an EPC.

For dwelling change of use or conversion you’ll need – Sap Calculations and an EPC.

For overglazing on an existing dwelling you’ll – Sap calculations only.

SAP or Standard Assessment Procedure are the computations of pre defined data set of a buildings design that’s put together to display the energy effectiveness of a building. An EPC or Energy Performance Certificate is a overview report produced by the Sap calculations that produces a SAP rating from 0 to 100. This rating is expressed on the Energy Performance Certificate as A the highest to G the lowest. It will also list recommendations which would improve the rating of your dwelling.

There are really 2 kinds of EPCs. The first is a SAP EPC that is produced from building plans where all the components of the building are known. This would normally be required by building control to demonstrate that a property complies with specified targets required by the building regulations. Building control would also need to see the SAP calculations which shows in detail whether all the elements going into the property comply with the building regulations.

The second variety of EPC is the typical one that would be needed if you are selling, or renting a property. This kind of EPC uses what’s called rdSAP, which stands for Reduced Data Standard Assessment Procedure, and is used where particular thermal values of, for instance, the walls, roof, floors, etc, usually are not precisely known on an existing property. In this case assumed thermal values are used depending on the age of the property. This sort of EPC will be no use to demonstrate compliance with any building regulations. Sometimes building control would simply ask you to get an EPC, however what they would really need are the Sap calculations (which is the data behind the EPC) and the SAP EPC (which is actually summary report from the Sap calculations).

Still confused, then simply contact us for further advice.

What Are As Built SAP Calculations

These will be the final set of SAP calculations generated after the building has been completed to hopefully demonstrate that it is compliant with Part L1A of the building regulations. Prior to the construction starting, it should have had a set of “Design Sap” calculations to demonstrate that the planned dwelling, in theory at least, will be compliant with Part L1A.



How To Do Sap Calculations

No, this is not some thing you can do by yourself. Sap calculations need to be done by an On Construction Domestic Energy Assessor or OCDEA, working with approved Government software programs. The Assessor needs to be approved under one of the certification schemes and is also regularly audited to maintain their qualification.

What Info is Needed For Sap Calculations

Your Assessor would advise you of exactly what is needed. Typically you would need the following:

  • Floor Plans to include sections and elevations
  • Orientation of the property
  • Construction specification of walls, roof and floors
  • Specification for all doors and windows
  • Primary and secondary heating
  • Provision for providing  hot water
  • Any renewable technology (if any)


Sap Calculations For New Build

Every new property need Sap calculations to show compliance with Part L1A (Conservation of fuel and power in new dwellings) of the building regulations.


Sap Calculations For Extensions

It’s now trendy to have large bi-folding doors, sky lights and large quantities of glazing on new extensions. But with the latest building regulations the amount of glazing can be no more than 25% of the floor area of the new extension. Therefore over compensations in the thermal elements in other places within the property will have to be made to demonstrate that the CO2 emissions from the current house along with the planned extension is no worse than the existing house and an extension whose glazing is within the allowed amount judged against Part L1B of the building regulations.

You will need SAP calculations to find solutions and show compliance.


Sap Calculations For Conversions

When you are altering the use of a building, you will need Sap calculations. {The new dwelling will have to comply with Part L1B of the building regulations.}


Do I Need Sap Calculations

You will need Sap calculations for any of the following: 

  • Building a new property
  • Changing the use of an existing property (e.g, a barn conversion, commercial building to residential)
  • Extensions with more than 25% glazing
  • Opening up the main house to an existing conservatory
  • Extension where the extension is more than 50% of the original property wall area
  • Garage conversions
  • If requested by building control

This is not an exhaustive list. If you’re uncertain whether you need them, then phone us.


Our Services

What You Can Expect From Us

Trusted & Experienced

Our Assessors are fully certified and accredited with many years experience carrying Sap calculation in East Acton . We also cover the whole of the UK and can help on any job nationwide.

Reliable & Fully Insured

You will be allocated a dedicated Assessor who is also covered by full professional indemnity insurance up to £100,000 so you know you’re in save hands.

Prompt Service

We’ll respond to your enquiry within 24 hours. We’ll also help you to deliver your project within your timescale.

Satisfaction Guaranteed

We aim to provide 100% satisfaction and look forward to working with you.


Get A Quote, Or Call Us For Advice