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Sap Calculations Willesden

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Sap Calculations, Just What Are They?

If you are reading this, you’ve probably recently been requested by another person, typically 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 on this page, where Andreas will shed some light on this, or continue reading.



Willesden SAP Calcs For Dwelling Change Of Use

  • Reports for Part L1B Compliance
  • Free Advice

Willesden SAP Calcs For Overglazed Extensions

  • Carbon Emissions Reports
  • Heat Loss Calculations
  • Free Advice

Willesden SAP Calcs For New Builds

  • Reports for Part L1A compliance
  • Free Advice

What does SAP mean?

SAP stands for Standard Assessment Procedure and is the UK government’s method of calculating the energy performance of dwellings. Sap calculations are necessary to prove that a building complies with specified energy targets laid down in the building regulations.

In a short summary, that’s basically it.


When Are SAP Calculations Needed?

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

1. For extensions that have more than the permitted amount of glazing
2. For all newly built properties
3. For a dwelling change of use, for example converting a commercial building to domestic flats.

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 construction drawings must be provided to the Assessor, as all the calculations are done from the building drawings ,so there is no need to visit the property. Your Assessor will advise you of precisely what is needed. When the calculations are done, an Energy Performance Certificate or EPC can also be created.

If your sap calculations show that your property is not compliant, your Assessor will give you recommendations on upgrades that can be made to make it so. It is important to liaise with your Assessor as early on in your project as possible because once the building is completed any non-compliances could be quite costly to rectify.

If you need advice on a project you may have in or around , or simply require a quotation, give us a call or fill in our get a quotation form. We’re here to help.


Questions On Willesden Sap Calculations, check if we have the answer here.

Sap Calculations, Just What Are They?

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

How Much Do Sap Calculations Cost

This might differ considerably dependant upon the size and complication of the dwelling, but a typical cost range will be between £120 – £300. There may be an additional fee of approximately £50 if an EPC is called for at the end of the build. For multiple dwellings of similar designs, then discounts could well be available.

What’s The Difference Between Sap and EPC

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

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 put together to demonstrate the energy effectiveness of a property. EPC means Energy Performance Certificate and it’s a summary report of the SAP calculations in an simple to comprehend document, which could also be used to market or rent out a property.

There are really 2 types 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 needed by building control to demonstrate that the property meets specified targets required by the building regulations. Building control would must also see the SAP calculations which illustrates in detail whether all the elements going into the property comply with the building regulations.

The 2nd sort of EPC is the regular one that will be required for anybody who is selling, or renting out a property. This type of EPC uses what’s called rdSAP, which means Reduced Data Standard Assessment Procedure, which is used where specified thermal values of, such as, the walls, roof, floors, etc, usually are not precisely known on an established property. In this situation assumed thermal values are used according to the age of the property. This kind of EPC will be no use to demonstrate compliance with any building regulations. Sometimes building control would simply ask you for an EPC, but what they would really need to have are the Sap calculations (which is the information behind the EPC) and the SAP EPC (which is a summary report of the Sap calculations).

If you are still perplexed, after that give us a call for further advice.

What Are As Built SAP Calculations

These will be the finished set of SAP calculations created once the building has been completed to confirm 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 demonstrate that the planned building, in theory at least, will be compliant with Part L1A.



Can I Do The Sap Calculation Myself

No, this is not something you can do yourself. Sap calculations need to be done by an On Construction Domestic Energy Assessor or OCDEA, by using approved Government computer software. The Assessor must be approved under one of the accreditation schemes and is regularly audited to keep up their qualification.

What Information 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

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 regulations.


Sap Calculations For Extensions

It’s now quite fashionable to get large bi-folding doors, sky lights and large quantities of glazing on new extensions. However under the latest building regulations the amount of glazing must be a maximum of 25percent of the floor area of the new extension. So over compensations in the thermal elements in other places within the property will have to be made to show the CO2 emissions from the current house and the planned 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 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.}


Will 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 require them, then simply phone us.


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 Willesden . We also cover the whole of the UK and can help on any job 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 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

We seek to provide 100% satisfaction and look forward to working with you.


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