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Sap Calculations Merton

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So, What Are Sap Calculations?

For anyone who is reading this article, you have more than likely been recently asked by another person, usually your building control officer, to supply 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 the video clip on this page, where Andreas will shed some light on this, or read on.



Merton SAP Calcs For Dwelling Change Of Use

  • Reports for Part L1B Compliance
  • Free Advice

Merton SAP Calcs For Overglazed Extensions

  • Carbon Emissions Reports
  • Heat Loss Calculations
  • Free Advice

Merton SAP Calcs For New Builds

  • Reports for Part L1A compliance
  • Free Advice

What does SAP mean?

SAP is short for Standard Assessment Procedure and is the UK government’s method of determining the energy performance of properties. The calculations are needed to prove that a building conforms with certain energy targets laid down in the building regulations.

As a brief summary, that’s essentially it.


When Are SAP Calculations Needed?

Sap calculations usually are required for three main reasons

1. For all new properties
2. For a dwelling change of use, e.g altering a single family home to residential flats.
3. For overglazed extensions

The 2 main areas which the sap calculations will look at is that the carbon emissions from the property are within set tolerances and that particular elements of the property, for example the floors, walls , roof, and windows comply with certain thermal targets.

A good set of building plans must be provided to the Assessor, because all the calculations are done from the building plans . Your Assessor will advise you of precisely what is needed. After the calculations are finished, an Energy Performance Certificate or EPC can also be created.

Your Assessor can provide further advice if the calculations show your building isn’t compliant, as well as let you know which would be the most effective changes to make. It is important to liaise with the Assessor as early on in your project as possible because once the building is completed any non-compliances could possibly be quite costly to rectify.

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


Want an answer to a query you have about SAP calculations in Merton? Listed below are the 10 most typical questions.

So, What Are Sap Calculations?

This is certainly quite possibly the most frequent 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 might can vary considerably dependant upon the size and complexity of the property, however a typical budget would be between £120 – £300. There may be an extra fee of around £50 if an Energy Performance Certificate is needed at the end of the construction. For multiple properties of similar designs, then discounts would be offered.

What’s The Difference Between Sap and EPC

Before we get to the differences, this 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 calculations of pre defined data set of a buildings design that’s created to show the energy performance of a dwelling. EPC means Energy Performance Certificate and it’s a summary report of the SAP calculations in an straightforward report, that could also be used to market or rent out a property.

There are really 2 types of EPCs. The first is a SAP EPC that is created from building plans where all of the elements of the construction are known. This will normally be required by building control to show that a property meets certain targets required by the building regulations. Building control would also have to see the SAP calculations which illustrates in detail whether the many elements going into your property conform to the building regulations.

The 2nd variety of EPC is the common one that would be required if you are selling, or renting a property. This particular EPC uses what’s called rdSAP, which means Reduced Data Standard Assessment Procedure, which is used where specific thermal values of, for example, 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 kind of EPC would be no good to show compliance with any building regulations. Sometimes building control would simply ask you for the EPC, however what they would really need are the Sap calculations (which is the information behind the EPC) and the SAP EPC (which is a summary report of the Sap calculations).

Still perplexed, after that give us a call for additional assistance.

What Are As Built SAP Calculations

These will be the final set of SAP calculations generated once the dwelling has been completed to confirm that it is compliant with Part L1A of the building regulations. Ahead of the project starting, it ought to have had a set of “Design Sap” calculations to show that the proposed building, on paper at least, would be compliant with Part L1A.



Can I Do The Sap Calculation Myself

Unfortunately this is not something you can do by yourself. The calculations need to be done by an On Construction Domestic Energy Assessor or OCDEA, working with approved Government software programs. The Assessor must be certified under one of the certification schemes and is regularly audited to keep their certification.

What Information is Required 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 demonstrate compliance with Part L1A (Conservation of fuel and power in new dwellings) of the building regulations.


Sap Calculations For Extensions

It’s now modern to get large bi-folding doors, sky lights and large quantities of glazing on new extensions. However with the existing building regulations the quantity of glazing must be a maximum of 25% of the floor area of the new extension. So over compensations on 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 along with the proposed extension is no worse when compared to the existing house and an extension where the glazing is within the allowed amount judged against Part L1B of the building regulations.

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


Sap Calculations For Conversions

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


Will 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 list is not exhaustive. If you’re uncertain whether you will need them, then give us a call.


Our Services

What You Can Expect From Us

Trusted & Experienced

Our Assessors are fully qualified and accredited with many years experience carrying Sap calculation in Merton . 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 of up to £100,000 so that 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.


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