SAP Calculation

What is SAP testing?

SAP stands for Standard Assessment Procedure. A SAP rating is given on a calculation – this is a figure between 1 and 100+. A figure of 1 would represent an extremely un-efficient home, anything above 100 would mean the dwelling is a net exporter of regulated energy. Since 2008, in response to the Energy Performance of Buildings Directive (EPBD), all new homes in the United Kingdom under construction require a Predicted Energy Assessment (PEA) and an On Construction Energy Performance Certificate (OCEPC).

SAPs are used in partnership with the PEA during a property’s design phase. This is done to achieve Building Control approval for the property; a legal requirement in the UK, according to Part L1a of Building Regulations (as with Air Tightness Testing.) Eecobuild have experienced in-house SAP assessors.

Our SAP calculations come with a pass guarantee based on our recommendations

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When a SAP Assessment is required

All new build dwellings require a SAP assessment. If your project is a barn conversion, a single dwelling into flats or a change of use it is likely that Building Control will ask for Part L1b SAP Calculations. If your project is an extension, and the glazing on the extension covers more than 25% of the extension area, you will likely need a SAP Calculation.

It is crucial to check whether your extension requires these calculations, in order to comply with Approved Document L.

SAPs tell the assessor and Building Control a number of important points about the property:

  • Whether or not the building exceeds the Target Emission Rate and Target Fabric Energy Efficiency Rate
  • The performance of the property with regards to its energy use
  • The Energy Efficiency Rating of the property

SAP Assessment testing FAQ's

Below you will find a collection of the most commonly asked questions regarding sound insulation testing

The calculation is typically split into two parts:

    1. The first part is the design stage. At this stage, the assessor will work up a preliminary SAP assessment based upon the proposed/assumed design and specification to see if compliance is met. If the dwelling is falling short of compliance, we work with our clients to find a solution which meets their requirements in terms or practically and budget.


  1. The second part is the as-built stage. This stage will take place once a dwelling nears completion and an air test has been carried out (if required). The assessor will upgrade all elements of the assessment with the final information and produce the as-built documents and issue the EPC

It’s important that both stages take place, initially to ensure that the proposed design will meet compliance and avoid having compliance issues at the end of the project and finally to sign-off the dwelling and begin use or marketing the property. At all stages, relevant documents will be provided to the client which can used to aid the progress, marketing or sign off of the project.

Having a SAP calculation carried out on a new build property is actually a government requirement in order to meet UK regulations. Before a building can be put to market, it is essential that it attains a ‘PASS’ from the result of the calculation based upon the relevant project and building regulation type – L1A or L1B.

It is also important to know that such assessment can’t be carried out by anyone, it must be done by an accredited company. Here at Eecobuild, we have the required accreditations to be able to carry out a full SAP assessment, along with the experience and knowledge to do the job properly.

As building regulations are forever getting tighter with a view to lowering carbon emissions across homes in the UK, this does impact the developer by meaning more higher specifications and reflectively more cost to achieve compliance. Here Eecobuild Ltd, we have expert knowledge and experience of all types of projects and aim to work with our clients to find the most suitable and cost effective manner to meet compliance on their projects.

Under Building Regulations Approved Document L, you will require a SAP calculation if you are:

  • Building any new build residential dwellings
  • Sub-dividing a residential property into more units
  • Converting commercial premises to residential dwellings
  • Putting an extension onto an existing residential dwelling, where the area of glazing is in excess 25% of the extension’s floor area.

We pride ourselves on being a reliable energy consultancy, and we have helped many homeowners, architects, self-builders and contractors gain a ‘PASS’ on their standard assessment procedure over the years.

The SAP services we offer are at an all-inclusive price, meaning we will support you right from your initial enquiry through to getting the result of your assessment – with our expert team always being there to guide you and answer any questions you may have.

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    Our FAQ’s section offers the answers to a lot of the commonly asked questions.

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