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Exactly What Are Sap Calculations

For anyone who is reading this, you’ve more than likely been requested by another person, normally your building control officer, to provide sap calculations for your building project. But you probably haven’t been told what sap calculation actually are and why you need them.

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



Leicester SAP Calcs For Dwelling Change Of Use

  • Reports for Part L1B Compliance
  • Free Advice

Leicester SAP Calcs For Overglazed Extensions

  • Carbon Emissions Reports
  • Heat Loss Calculations
  • Free Advice

Leicester 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 calculating the energy efficiency of buildings. These calculations are needed to illustrate that a building conforms with certain energy targets laid down in the building regs.

In a simple overview, that’s essentially it.


When Are SAP Calculations Needed?

Some of the reasons you will be asked for sap computations
1. For all newly built properties
2. For a dwelling change of use, for example changing a commercial building to flats
3. For extensions that have more than 25% glazing

The sap calculations have to demonstrate that the dwelling emission rate (DER) and the dwelling fabric energy efficiency (DFEE) conform to certain targets.

The computations will be carried out by a professional and approved On Construction Domestic Energy Assessor. There is no need to visit the property as all the computations are carried out from the building drawings ,so a good set of plans are very important. An EPC or Energy Performance Certificate can be produced once the computations are finished.

If your sap calculations reveal that your property is not compliant, then your Assessor will give you information on upgrades that may be made to make it so. It is crucial that you liaise with your Assessor as early on in the project as possible because once the building is finished any non-compliances might be quite costly to rectify.

If you require advice on a project you could have in Leicester , or require a quote, give us a call or fill in our get a quotation form. We’re here to help.


Rather than trawl through a whole website to get the answers you’re looking for, we have supplied answers to the 10 most common queries asked about SAP in Leicester.

Exactly What Are Sap Calculations

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

Sap Calculations, How Do They Cost

The average price range is between £100 – £300, this is depending upon the difficulty and proportions of your property. For those who also require an Energy Performance Certificate (EPC) at the end of it there may be a further charge of about £50 to register the EPC on the epc register. For a number of dwellings of comparable types, then discounts could be available.

What Is The Difference Between Sap and EPC

Before we get to the differences, here is what you will need depending on your project.

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 created to demonstrate the energy effectiveness of a building. EPC means Energy Performance Certificate and it’s a summary statement from the SAP calculations in an straightforward document, which could also be used to sell or rent out a property.

There are really 2 kinds of EPCs. First is a SAP EPC that is produced from building plans when all the components of the building are known. This would normally be required by building control to show that the dwelling meets certain targets essential to the building regulations. Building control would must also see the SAP calculations which illustrates in detail whether the many elements going into your property conform to the building regulations.

The 2nd type of EPC is the standard one that will be necessary when you are selling, or renting out a property. This kind of EPC uses what’s called rdSAP, which means Reduced Data Standard Assessment Procedure, and is used where specified 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 your property. This type of EPC will be no use to show compliance with any building regulations. Sometimes building control would simply ask you to get an EPC, however what they would really need to have are the Sap calculations (which is the data behind the EPC) and the SAP EPC (which is actually summary report from the Sap calculations).

If you are still confused, then simply call us for further assistance.

What Are As Built SAP Calculations

These will be the finished set of SAP calculations produced after the building has been completed to show 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 show that the planned building, in theory at least, will be compliant with Part L1A.



Can I Do The Sap Calculation Myself

Unfortunately this is not some thing you could do by yourself. The calculations must be done by an On Construction Domestic Energy Assessor or OCDEA, working with approved Government computer software. The Assessor must be certified under one of several accreditation schemes and is regularly audited to keep up their accreditation.

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 dwelling need to have Sap calculations to prove compliance with Part L1A (Conservation of fuel and power in new dwellings) of the building regs.


Sap Calculations For Extensions

It’s now fashionable to have large bi-folding doors, sky lights and large amounts of glazing on new extensions. However with the existing building regulations the quantity of glazing can be no more than 25% of the floor area of the new extension. So over compensations in the thermal elements in other parts of the property will need to be made to show that the CO2 emissions coming from the existing house and the planned extension is no worse than the existing house and an extension where the 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

For anybody who is changing 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 to have 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 checklist. If you’re uncertain whether you will need them, then simply contact us.


Our Services

What You Can Expect From Us

Trusted & Experienced

Our Assessors are fully qualified and accredited with many years practical experience carrying Sap calculation in Leicester . We also cover the whole of the UK and can help on any project nationwide.

Reliable & Fully Insured

You will be allocated a dedicated Assessor who is also covered by full professional indemnity insurance up to £100,000 to ensure 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

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