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Sap Calculations London

Fast and simple Sap computations from local certified Assessors. Call us to get a quote on your project.

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So, Just What Are Sap Calculations

Have building control, or maybe your architect requested that you get sap computations. But why do you need them and what exactly are sap calculations anyhow? Then read on.

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

SAP stands for Standard Assessment Procedure and it is the United Kingdom government’s procedure for calculating the energy performance of dwellings. These calculations are needed to demonstrate that your building complies with specified energy targets set down in the building regulations.

In a brief overview, that’s basically it. 

Sap Assesments are usually required for 3 main reasons

  • For all newly built properties.
  • For a dwelling change of use, such as modifying a commercial building to residential flats.
  • For overglazed extensions|{Sap calculations are usually required for 3 main reasons.

There are two main targets that the sap calculations are required to demonstrate. Firstly that the dwelling emission rate (DER) and the dwelling fabric energy efficiency (DFEE) comply with certain targets.

A good set of building drawings must be given to the Assessor, because all the calculations are done from the building drawings . Your Assessor will advise you of precisely what is needed. 

After the calculations are finished, an Energy Performance Certificate or EPC can also be produced.

Your Assessor can provide you with further advice if the calculation show your dwelling isn’t compliant, as well as explain to you which would be the most effective changes to make.

It could be costly if you find out at a late phase in the construction that your building is not compliant. So it’s wise to liaise with the Assessor as early on in the project as possible.

Should you require guidance on a project you may have in London, or require a quotation, give us a call or fill in our get a quote form. We’re here to help.

Sap Assessor

SAP Calculations in London The 10 Most Typical Questions Asked.

What Are As Built SAP Calculations

These will be the finished set of SAP calculations produced once the building has been completed to confirm that it is compliant with Part L1A of the building regulations. Ahead of the building starting, it should have had a set of “Design Sap” calculations to demonstrate that the planned dwelling, on paper at least, would be compliant with Part L1A.



So, Just What Are Sap Calculations

This is probably the most common query asked. Have a look at Andrea’s video explanation above, or read the full explanation here on the right.

What Is The Cost Of Sap Calculations
This will vary considerably depending on the size and complication of the dwelling, however an average cost range would be between £120 – £300. There will probably be an additional cost of about £50 if an EPC is needed at the end of the construction. Reductions would typically be available for a number of properties especially when they are of the same form of design.
How To Do Sap Calculations

No, this is not some thing that can be done yourself. Sap calculations have to be done by an On Construction Domestic Energy Assessor or OCDEA, by using approved Government software. The Assessor needs to be certified under one of the accreditation schemes and is also regularly audited to maintain their certification.

What Information is Required For A Sap Assessment

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 Assessment For New Build

All new dwelling need to have 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 quite trendy to get large bi-folding doors, sky lights and large amounts of glazing on new extensions. But with the latest building regulations the amount of glazing must be no more than 25percent of the floor area of the new extension. So over compensations in the thermal elements in other areas within the property will need to be made to show the CO2 emissions from the existing house along with the planned extension is no worse than the existing house and an extension whose glazing is within the permitted amount judged against Part L1B of the building regulations.

You should have SAP calculations to find solutions and demonstrate compliance.


Sap Calculations For Conversions
When you are modifying the use of a building, you will require Sap calculations. {The new dwelling will have to comply with Part L1B of the building regulations.}


Do I Need Sap Calculations
p>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 list is not exhaustive. If you’re not certain whether you will need them, then simply contact us.


Our Services


SAP For Dwelling Change Of Use

  • Reports for Part L1B Compliance
  • Free Advice

SAP For Overglazed Extensions

  • Carbon Emissions Reports
  • Heat Loss Calculations
  • Free Advice

SAP For New Builds

  • Reports for Part L1A compliance
  • Free Advice

What You Can Expect From Us

Trusted & Experienced

Our Assessors are fully certified and accredited with several years experience carrying Sap calculation in London . We also cover the whole of the UK and can assist on any project nationally.

Reliable & Fully Insured

You will be assigned a dedicated Assessor who is also covered by full professional indemnity insurance of 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 seek to provide 100% customer satisfaction and look forward to working with you.


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