What is a Standard Assessment Procedure (SAP) calculation?

Standard Assessment Procedure (SAP) calculations are used as part of the Building Regulation requirements.  They establish that new dwellings meet the minimum requirements established for energy performance and efficiency.  A SAP calculation produces a Predicted Energy Assessment and ultimately an On-Construction Energy Performance Certificate for a new domestic building.

Approved Document L1A establishes the requirements in England for new dwellings in terms of energy performance.  Similar documents exist for the devolved administrations of Scotland, Wales and Northern Ireland.  Additionally, local authorities can also have their own requirements in addition to these which they maintain through their Planning and Permitted Development systems.

Whilst there are some key differences between all these requirements, the core methodologies remain similar.  The documents establish minimum standards for each element and system to ensure that they are efficient both in terms of energy and carbon emissions.  However, these are minimum standards.  Each administration requires that the home overall exceeds these minimums to meet standards for carbon emissions, energy efficiency and primary energy use.

The Standard Assessment Procedure (SAP) provides these values based on:

  • The elements of structure;
  • The internal lighting;
  • The heating;
  • The hot water system;
  • Any renewable technologies installed in the home.

In terms of Energy Performance, a rating based on expected energy costs is used.  This is the same as that seen on the Energy Performance Certificate (EPC).  The higher the score, the lower the running costs.  On this scale 100 represents zero energy cost.  Dwellings with a rating in excess of 100 are net exporters of energy.

The rating produced by a SAP calculation is largely location independent.  It is also based on a notional occupancy to overcome the different ways in which people use their homes.  As a result, SAP calculations allow the energy running costs of dwellings anywhere in the UK to be compared.