SAP calculations should be thought about carefully throughout the entire process of the built project to ensure that your property meets building regulations.

During design stage, the SAP calculation will advise decision makers in a built project on the specification of materials you need during the build. At the end of the build, Building Control will need to ensure that you have fulfilled your SAP requirements.

SAP calculations ebook | Sustain quality


At what point should you arrange your SAP assessment?

The SAP calculations need to be submitted to Building Control before construction can begin, meaning that it’s important to arrange your SAP at the earliest possible stage.

However, waiting until your design drawings are complete could mean that you have to rethink elements of your proposed building fabric and/or technologies. When a small alteration is made, for example, the size of your cavity wall insulation, it could reduce your internal space or increase the size of your build.

Therefore, liaising with architects and designers during the design stage will streamline the process and allow plenty of time for materials to be ordered. This reduces the risk of product deviation, saving you time-and potentially money, too.

As-Built SAP Calculations

Once the property has been constructed, a final EPC will be required from Building Control. This is taken from an ‘As-built’ SAP calculation.

The As-build SAP will determine whether the dwelling still meets the requirements of Building Regulations as set out during the design stage. If any changes to the property have been made during the construction/development and was not previously highlighted during the planning phase, your final SAP will need to reflect this.

If there are significant changes made to the property, this could alter the initial SAP rating, resulting in the Dwelling Emission Rate (DER) and the Dwelling Fabric Efficiency (DFEE) exceeding the targets set during the design stage. If this is the case, the property will be unlikely to achieve final approval, meaning that it cannot be marked for sale or let.

What is involved in an As-Built EPC?

It is likely that an Air Pressure Test will be required before beginning any SAP calculation. This measures the air leakage of the dwelling. The results of this test are then fed directly into the SAP calculation alongside information from the finished plans (this will include any variations).

If the plans and final SAP calculation has remained the same, a SAP assessor will produce the required SAP report for the client. If any changes have taken place, this will need to be added to the report. Please note, however, that there is a possibility that the structure may no longer be compliant. In this event, the SAP assessor will advise on any improvements in regards to energy efficiency, ensuring that your building will meet the required rules and regulations.

Does the same company have to conduct the Design Stage SAP and As-Built SAP?

A building project can be a lengthy process, taking years to complete in some stages. Therefore, different companies can conduct SAP calculations for the Design Stage SAP and As-built SAP.

However, we do recommend that you choose one company to carry out the SAP calculations for the duration of the project to ensure efficiency.


A SAP calculation is a multi-step process, meaning that more than one SAP will need to be carried out during the built process.

If you would like to find out more about our SAP calculation services or would like to speak to one of our team members about energy advice for your property, get in touch on 01372 438 039 or fill out the form below and we’d be more than happy to help.


SAP calculations ebook | Sustain quality


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About Us

We are a friendly team of Engineers delivering Sustainability and Building Compliance Solutions for developments in the Commercial and Residential sectors, which include Energy Statements, Noise Impact and Vibration Assessments, BREEAM Assessments, and Air Quality Assessments in the Environmental, Social and Governance sectors.

Contact us at:

Sustain Quality Ltd

PO Box 393


KT11 3EL

01372 438039