Address: Unit 3, Churchtown Business Park, Churchtown, Dublin 14 Phone: +353 1 298 3000 Email:

Air Tightness Testing

Air tightness testing is a method of measuring the extent to which air is lost through leaks in the building fabric. It is sometimes referred to as air leakage testing or air pressure testing. Air tightness testing is now mandatory for all new residential and commercial buildings in Ireland as too much air leakage leads to unnecessary heat loss and discomfort for the occupants.

Our NSAI certified testers have years of experience in conducting tests on residential and commercial buildings and are experts in providing advice on how to rectify poor test results. We have also invested significantly in multi fan testing capability to be able to perform tests on very large commercial buildings.

CERL’s staff members are highly qualified and follow the strictest air tightness test procedures defined by NSAI’s certified air tightness testing scheme and to ISO 9972: 2015 Thermal Performance of Buildings – Determination of Air Permeability of Buildings – Fan Pressurization Method

Air Tightness Testing Procedure

  • Pre test measurements: CERL engineers will measure air temperatures and wind speeds and check that the building dimensions correspond to the drawings.
  • Building preparation: Select a suitable opening to install the fans (normally the front entrance), seal all extract fans, close all adjustable ventilation openings, ensure that all traps are filled with water.
  • Measure depressurisation rate: Check for obvious leakage paths, create 50 Pascal pressure difference, air flow measurements are taken at a number of pressure differentials.
  • Measure pressurisation rate: Rearrange test equipment, re-check all seals and test conditions, create 50 Pascal pressure difference, take a further number of pressure differentials.
  • Indicative test results: The results of the test are reviewed in terms of airflow per metre squared at a pressure of 50 pascals and if the target airtightness result is not achieved then the building can be investigated further for the cause of this.

Smoke Test

If a unit has not met the air tightness criteria, then a leakage investigation will be carried out. This can be in the form of visual inspection of potential weak areas and by means of a smoke test. For small units, a localised smoke test can be carried out which disperses a small cloud of smoke. For larger units, a larger smoke machine will be used. It is advised that smoke alarms be isolated and smoke heads covered. Informing the client that the air test has failed, and the smoke test will commence. Also, recommending the client inform nearby units/public. Once the smoke test has finished, leaving external windows and doors open will allow the remaining smoke to dissipate. During the smoke test, CERL engineers shall take photos and videos throughout the smoke test. CERL will provide a report based on the smoke test. Once these issues have been rectified then a retest will take place.