SAP Calculations

At Vertex Energy, our certified On Construction Domestic Energy Assessors (OCDEAs) deliver a comprehensive SAP/EPC service. Whether you’re a homeowner or a national construction company, we provide a professional, experienced service with a fast turnaround.

We calculate SAP values based on key factors that influence energy consumption, including heating systems, insulation, air tightness, ventilation, lighting, and U-value calculations. With our expertise in building construction, we also guide you on methods and materials to help your development achieve optimal energy efficiency.

The Standard Assessment Procedure (SAP) is the UK Government’s method for energy rating dwellings. We use it to calculate the energy performance of buildings and demonstrate compliance with Part L of the Building Regulations.

During the construction of your new building, we typically produce a SAP twice:

• Design Stage SAP – We carry out the Dwelling Emission Rate (DER) and Target Emission Rate (TER) calculations and submit them to local building control before work begins. If the property is to be sold off-plan, we can create a Predicted Energy Assessment (PEA).

• As-built SAP – We conduct this near the completion of construction to confirm that the building meets compliance standards. We then produce an Energy Performance Certificate (EPC) and lodge it.

Part L of the Building Regulations, which is split into two sections, outlines the requirements for new build properties in Part L1A, while Part L1B covers the regulations for conversions and extensions.

If you’re converting an existing building, prepare the initial SAP calculations at the design stage and submit them to local building control before starting any development work.

Once you complete the conversion, prepare an as-built SAP calculation that reflects any design changes and the final details of heating, hot water, and ventilation systems.

Then, produce the final SAP report and submit it to building control, along with an On Construction Energy Performance Certificate (EPC). Building control requires the EPC before issuing the completion certificate, and you’ll need it for the property’s sale or rental.

To comply with Building Regulations Part L1, you should undertake SAP calculations at the design stage, during construction, and on completion of the build process. This approach ensures you can account for and address any changes during the build that may impact the project’s overall energy rating.

By involving Vertex Energy early in the design process, we can produce the required SAP calculations and Predicted Energy Assessment (PEA) while offering expert advice on construction methods to achieve optimal energy efficiency. Once you complete the build, we will also provide the necessary Energy Performance Certificate (EPC).

The earlier you appoint a SAP assessor, the greater your chances of success. Early involvement allows for a thorough review of your design, helping to identify potential issues before they arise.

Using the plans and drawings provided at the design stage, the assessor inputs data into approved software to assess whether the proposed dwelling complies with Building Regulations for fuel and power conservation. If the initial specification doesn’t meet the requirements, the assessor can model alternative designs to achieve compliance.

The assessor will identify any shortfalls and recommend solutions to the designer. You can then incorporate these changes into the revised design, ensuring the SAP calculations are compliant and ready for submission to building control.

Achieving compliance with Building Regulations Part L requires careful planning. Successful SAP calculations play a key role in this process. Ideally, construction should not commence unless you are confident the specification fully meets the necessary requirements.

If your SAP fails at the design stage, there is no immediate cause for concern. This desk-based exercise occurs before construction begins, allowing the assessor to model alternative designs and suggest adjustments to ensure compliance.

However, failing at the as-built stage can be costly. Insufficient insulation or incorrect heating and ventilation systems may necessitate extensive remedial work or new installations. To avoid this, ensure the specification aligns with SAP requirements from the outset.

A SAP rating is calculated based on various factors, including space heating, water heating, ventilation, lighting, and potential cost savings from energy generation technologies such as renewables.

We gather information from sources like floor plans, elevations, site plans, build specifications, and proposed heating and ventilation systems. Then, we enter this information into accredited software to generate the draft SAP report. The software grades the building’s SAP rating on a scale of 1 to 100, with 100 representing zero energy costs.

A Predicted Energy Assessment (PEA) is produced as part of the design stage SAP, if required. It is often necessary for building and construction companies that sell properties off-plan, before the building is constructed. A valid PEA is required to proceed with these sales.

The PEA is also used during the early stages to identify areas for improvement, helping to raise the PEA/EPC rating if necessary.

An Energy Performance Certificate (EPC) measures the energy efficiency and CO₂ emissions of a building upon completion of construction. It forms part of the as-built SAP and includes recommendations for improving the property’s energy performance. We will issue the EPC and lodge it, allowing the property to be signed off and sold.

Before we can issue the EPC, we must conduct a successful Air Leakage Test within the new building. We will also provide the necessary Air Test reports and certificates, along with Part G Water Consumption Calculations, to confirm that regulatory standards have been met.

To complete a SAP calculation accurately, we require scaled architectural drawings (floorplans, elevations, and sections), construction specifications (including insulation types and thickness), U-values of external elements, heating and hot water system specs, ventilation systems, and any renewable technologies. Providing this information early ensures a smoother, faster process and better results.

Yes, but it’s important to consult your SAP assessor before implementing changes. Any modification to insulation, heating systems, window specifications, or building layout can affect your SAP rating. If changes are made after the Design Stage SAP is complete, a revised assessment may be needed to ensure ongoing compliance with Building Regulations. Early communication with your assessor helps prevent delays or failed assessments at the as-built stage.