Three steps to compliance are:


1. SAP Assessment.Using the specifiers information this Standard Assessment Procedure is the Governments' method for the energy rating of dwellings. Within this calculation an air tightness value of the dwelling is selected.

The minimum requirement is 10m3/h m2 at a pressure differential of 50Pa. If better values of air tightness are specified then savings may be made in other areas.

Link to SAP explanation:

2. Air Tightness Testing. The air tightness test is a non-destructive check of unwanted ventilation i.e. drafts, resulting from poor specification, materials and workmanship. The on-site test result should be at least equal to the value used in the SAP assessment.

3. Problem resolution. Problems at this late stage of the build process are unwanted, which is why Building Test Services will assist to help quickly resolve air test failure issues.


  • Q. What happens if the air tightness test fails to achieve the figure stated in the SAP assessment?
  • A. During the on site test, Building Test Services offer a free of charge service to help analyse the source of leaks using smoke stick detection methods and suggest remedial actions that can be completed on the day so that a re-test can be conducted to record the best possible air tightness test.
  • Q. What happens if the improvement still fails to achieve the SAP figure?
  • A. Building Test Services will re-run the SAP assessment using the actual air tightness figure to establish the overall effect upon the energy rating of the dwelling. This is a free of charge service and may provide a satisfactory result or identify other areas that could be improved to achieve a pass.
  • Q. What happens if a re-test is required on another day?
  • A. Building Test Services will return to site and re-test the dwelling at 50% discount.