Air Tightness Testing for PAS2035

The PAS 2035 standard and the requirements it sets out is to encourage a shift to a whole-building approach. One of the main focus of PAS 2035 is the connection between thermal insulation and the building fabric to include walls, floors, glazing, doors and roofs and the impact this can have on reduced air leakage and ventilation design. As this is fairly new to the retrofit sector this currently a lot of confusion as to the best approach to satisfy the PAS2035 requirements air tightness and ventilation in existing buildings; however, it really that that complicated.


New MVHR systems do not work properly in leaky dwellings

There are numerous pathways to attain an energy efficient building; however, we think that if you can’t measure air leakage through the existing building fabric, how can you provide an energy efficient building. Although air tightness testing is only mandatory for PAS2035 Pathway C projects, and also at the discretion of Retrofit Coordinators. Our small powerful fan systems allow air tightness testing to be carried out in under an hour. This means you have an actual test and data for the building’s envelope and not just hypothetical data worked from computer programmes – which can often be misleading.

We have been involved in previous retrofit projects where the M&E design was built around an air leakage rate between 3-5m3/hr/m2; however, when tested the dwelling achieved an air leakage rate in excess of 15 m3/hr/m2! in this instance the proposed MVHR system wouldn’t have worked properly. Using our air tightness testing, smoke leakage surveys and remedial sealing services, we were able to lower the dwellings air leakage rate to below 5m3, which meant the ventilation system worked properly, and the client ended up with a building that was 20-30% lower in heating costs with far less drafts.


So, as the air tightness test can be carried out quickly and easily, it makes logical sense to measure all PAS2035 retrofit buildings, both before (pre-works) and after the retrofit (post-works). Using this information, stakeholders can work from an informed position and risks can be more readily managed with M&E design etc.

We can help with the Air Leakage Testing for your PAS2035 Project

If you would like more information in for our PAS 2035 air tightness testing services, please contact us at info@airpressuretesting or visit our call us on 01525 303905. Alternatively  please see a copy of our air leakage checklist to help you prepare for your PAS2035 Air Test.