About SAP Calculation

What is a SAP Calculation?

SAP is the Governments 'Standard Assessment Procedure' for energy rating of dwellings. It is a compulsory component in complying with the Building Regulations for new dwellings and where existing buildings are converted to dwellings.

SAP provides a simple means of reliably estimating the energy efficiency performance of dwellings. SAP ratings are expressed on a scale of 1 to 100 the higher the number the better the rating. Thus SAP is similar to the fuel consumption of a car under standard driving conditions.

How is it calculated?

SAP is calculated by a procedure contained in the Building Regulations, which predicts heating, and hot water costs. These depend on the insulation and air tightness of the house and the efficiency and control of the heating system.

SAP programs are used to enter data on the size of the house, its insulation levels, it ventilation system and its heating and hot water systems. SAP rating can then submitted for Building Regulations approval and is checked by the local Building Control department.

The first part of the SAP calculations involves calculating a Target Energy Rating (TER) for the dwelling. The next step in the SAP report process is to calculate the Dwelling Emission Rate (DER). If this is equal to or less than the TER then the SAP rating shows a pass and the SAP calculations are complete.

If the DER is not equal to or less than the TER then we will liase with you and suggest changes that will improve the DER to ensure that the SAP calculations show a pass.

What is the difference between a SAP calculation and an Energy Performance Certificate?

The SAP calculation is the method used for demonstrating compliance with the Building Regulations whereas the Energy Performance Certificate enables the end user of the building to see how Energy Efficient the building is. The Energy Performance certificate is very easy to understand at first glance whereas the SAP Calculation contains a lot of detailed calculations and figures.

The two are linked though as the Energy Performance Certificate is calculated using the information contained within the SAP calculation.

At what point should the SAP calculation be undertaken?

It is recommended that a Design SAP calculation be carried out at early design stage to check that the building will comply with the carbon emission requirements contained within the calculation. If the requirement is not met then changes will need to be made to achieve compliance. An ‘As Built' calculation will then be required at the end of the project.