Lambeth Top Sap Assessors

Need Sap calculations for either Part L1A, or Part L1B, we’re here to help. Contact us for a quotation for your project.

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Need to have an answer to a query you have about SAP calculations in Lambeth? Here are the ten most frequent questions.

So, Exactly What Are Sap Calculations

This is quite possibly the most frequent question asked. Take a look at Andrea’s video explanation above, or read the full explanation here on the right.

How Much Are Sap Calculations

We will be pleased to offer you discount rates, especially for multiple dwellings that are of the same or similar design. But typically for a single dwelling the charge would be in the area of £120 – £300. By supplying the plans, it will be possible to get a fixed price quote.

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 computations of pre defined data set of a buildings design that’s put together to show the energy efficiency of a property. EPC is short for Energy Performance Certificate and it’s a summary statement of the SAP calculations in an straightforward document, which can also be used to market or rent out a property.

There are really 2 kinds of EPCs. First is a SAP EPC which is created from building plans where all of the elements of the building are known. This would normally be needed by building control to show that the dwelling satisfies specific targets essential to the building regulations. Building control would also need to see the SAP calculations which illustrates in greater detail whether the many elements going into the property comply with the building regulations.

The second sort of EPC is the standard one that will be required if you are selling, or renting a property. This type of EPC uses what’s called rdSAP, which is short for Reduced Data Standard Assessment Procedure, and is used where particular thermal values of, for example, the walls, roof, floors, etc, usually are not precisely known on an existing property. In this instance assumed thermal values are used depending on the age of the property. This type of EPC would 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 a summary report of the Sap calculations).

Still confused, then phone us for further information.

What Are As Built SAP Calculations

These are the finished set of SAP calculations created once the dwelling has actually been completed to confirm that it is compliant with Part L1A of the building regulations. Ahead of the building 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.



How To Do Sap Calculations

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

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


Sap Calculations For Extensions

It’s now modern to get large bi-folding doors, sky lights and large amounts of glazing on new extensions. But with the present building regulations the quantity of glazing must be a maximum of 25percent of the floor area of the new extension. So over compensations on the thermal elements in other places of the property will have to be made to show that the CO2 emissions coming from the existing house and the proposed extension is not any worse when compared to the existing house and an extension where the glazing is within the permitted amount judged against Part L1B of the building regulations.

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


Sap Calculations For Conversions

For anyone who is altering the use of a dwelling, you will need 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. Give us a call, if you are unsure if you need them.


So, Exactly What Are Sap Calculations

If you are reading this, you have probably been recently requested by someone, usually your building control representative, 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.

SAP is short for Standard Assessment Procedure and it is the UK government’s procedure for calculating the energy performance of properties. The calculations are required to illustrate that your building conforms with specific energy targets set down in the building regs.

As a simple overview, that’s basically it.

A few 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 two main areas that the sap calculations will be looking at is that the carbon emissions from the dwelling are within set tolerances and that certain elements of the property, for example the walls, windows, floors and roof comply with specified thermal energy targets.

Sap computations will be carried out by a professional and accredited On Construction Domestic Energy Assessor. There is not any need to visit the property because all of the computations are carried out from the building plans . When the calculations are finished, an Energy Performance Certificate or EPC can also be produced.

If your sap calculations show that your property is not compliant, then Assessor will give you guidance on upgrades that can be made to make it so. It is essential to 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 need advice on a project you could have in or around Lambeth, or require a quote, call us or fill in our get a quotation form.


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 years practical experience carrying Sap calculation in Lambeth . We also cover the whole of the UK and can assist 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 which means 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% satisfaction and look forward to working with you.


Get A Quote, Or Call Us For Advice