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Sap Calculations Waltham Forest

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Sap Calculations, What are They?

If you are reading this, you’ve probably recently been requested by somebody, typically your building control representative, to provide sap calculations for your building project.

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



Waltham Forest SAP Calcs For Dwelling Change Of Use

  • Reports for Part L1B Compliance
  • Free Advice

Waltham Forest SAP Calcs For Overglazed Extensions

  • Carbon Emissions Reports
  • Heat Loss Calculations
  • Free Advice

Waltham Forest SAP Calcs For New Builds

  • Reports for Part L1A compliance
  • Free Advice

What does SAP mean?

SAP is short for Standard Assessment Procedure and it is the united kingdom government’s means of calculating the energy efficiency of properties. These calculations are necessary to illustrate that a building complies with specific energy targets laid down in the building regs.

In a simple overview, that’s essentially it.


When Are SAP Calculations Needed?

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

1. For all new homes
2. For a dwelling change of use, for example altering a commercial building to domestic flats.
3. For extensions that have more than 25% glazing

The 2 main areas that the sap calculations will be looking at is that the carbon emissions from the property are within set tolerances and that certain components of the property, such as the walls, roof, windows and floors comply with certain thermal energy targets.

The computations are 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 drawings ,so a good set of plans are very important. Once the calculations are done, an Energy Performance Certificate or EPC can also be created.

Your Assessor can give you further advice in the event the calculations show your building isn’t compliant, as well as advise you which will be the most effective improvements to make. It can be costly if you realise at a late stage in the construction that the building isn’t compliant. So it’s advisable to liaise with your Assessor as early on during the project as possible.

Should you require guidance on a project you could have in or around , or require a quotation, call us or fill in our get a quotation form.


Rather than trawl through a whole website to get the answers you’re trying to find, we’ve supplied answers to the 10 most typical questions asked about SAP in Waltham Forest.

Sap Calculations, What are They?

This really is by far the most frequent question asked. Have a look at Andrea’s video explanation above, or read the full explanation here on the right.

How Much Are Sap Calculations

If there are multiple properties with similar forms of constructions, then reductions may apply. For single dwellings you would then be looking in the range of £120 – £300 depending upon the difficulty of your building along with the size. By providing the plans, you will be able to get yourself a fixed price quotation.

What’s The Difference Between Sap and EPC

Before we explain the difference, here is what you will require 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 properties design that’s put together to display the energy performance of a building. EPC stands for Energy Performance Certificate and it’s a summary statement of the SAP calculations in an simple to comprehend report, which can also be used to sell or rent out a property.

There are actually 2 types of EPCs. First is a SAP EPC that is produced from building plans when all of the components of the construction are known. This will normally be required by building control to show that a property complies with specific targets required by the building regulations. Building control would must also see the SAP calculations which shows in greater detail whether all of the components going into the property comply with the building regulations.

The 2nd type of EPC is the regular one that will be needed for anybody who is marketing, or renting a property. This kind of EPC uses what’s called rdSAP, which stands for Reduced Data Standard Assessment Procedure, which is used where certain thermal values of, for instance, the walls, roof, floors, etc, usually are not precisely known on an established property. In this situation assumed thermal values are used depending on the age of the property. This particular EPC would be no use to show compliance with any building regulations. Sometimes building control would simply ask you for the 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 of the Sap calculations).

If you are still perplexed, after that call us to get more assistance.

What Are As Built SAP Calculations

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



How To Do Sap Calculations

No, this is not something that you can do yourself. The calculations have to be carried out by an On Construction Domestic Energy Assessor or OCDEA, by using approved Government program. The Assessor has to be certified under one of the accreditation schemes and is also 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 property need to have 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 have large bi-folding doors, sky lights and large amounts of glazing on new extensions. However with the present 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 areas of the property will need to be made to show the CO2 emissions coming from the existing house along with the planned extension is not any 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 illustrate compliance.


Sap Calculations For Conversions

When you are 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 checklist is not exhaustive. Contact us, if you are not sure if you require them.


Our Services

What You Can Expect From Us

Trusted & Experienced

Our Assessors are fully qualified and accredited with several years practical experience carrying Sap calculation in Waltham Forest . 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 and that 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 aim to provide 100% satisfaction and look forward to working with you.


Get A Quote, Or Call Us For Advice