SAP Calculations and EPC

What is a SAP Calculation?

SAP stands for Standard Assessment Procedure (SAP) and is the official methodology used by the Government to assess the energy efficiency rating of a new dwelling as well as conversions renovations or extensions. 

It is a dwelling energy modelling tool which creates an energy cost  and CO2 emissions based on the construction of a new property and takes into account several elements of the building, from:
– the structure
– fabric elements e.g. wall insulation (u-values)
– ventilation e.g. air tightness
– heating efficiency
– heating controls
– lights
– renewable technologies.

It then produces a dwelling emission rate, which is compared with a building regulations target emission rate.

The SAP rating also produces a score between one and 100. The higher the SAP rating, the lower the fuel costs, and the lower the associated emissions of carbon dioxide.

Why is a SAP Report required?

SAP is a mandatory requirement of Building Regulations Part L1A (new build) and Part L1B (existing) and without it, you will not be granted building sign off.

Part L1A applies to new dwellings and one of its objectives is to ensure that all new buildings increase their energy efficiency ratings to meet the targets set by the Government.

For Part L1A Building Regulations, a SAP calculation is required by building control at the Design Stage as well as a predicted energy certificate.

These calculations can only be carried out by an accredited On Construction Domestic Energy Assessor (OCDEA).

The SAP calculation will then need to be finalised at the As Built Stage and an Energy Performance Certificate (EPC) will then be provided.

An EPC is a summary certificate based on the SAP calculation and gives a property its energy efficiency rating. It is needed for when you sell a property and it is mandatory to provide this to building control.

How can we help?

At Base, we are here to guide you through the SAP process and offer a seamless transition to help you meet compliance as quickly and as easily as possible. Our services include:

  • Design Stage SAP Calculations
  • SAP Design and compliance advice
  • Predicted Energy Certificate
  • U-value calculations
  • As Built SAP Calculations
  • Energy Performance Certificate

Our assessors are highly experienced in completing SAP calculations, we are fully

OCDEA accredited and can issue EPCs.

They will work with you to provide the most practical solutions to help you achieve a pass as well as offer guidance to help your development to go beyond building regulations.

We can also provide energy efficiency ratings via SAP calculations on properties under Building Regulations Part L1B for conversions, renovations and extensions.

As SAP is a desktop exercise, all we require to complete your SAP calculation is copies of plans and specifications which can be emailed to us at

A site visit can also be arranged if required to provide advise on the design of the building to help pass the SAP calculation. We can also apply discounts to developments with multiple properties.

If you would like to discuss a SAP calculation, please call us on 020 3286 2016 or email and we will get back to you within the same working day.

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