FAQ – Air pressure testing

Why should we build air tight dwellings?

The energy that we utilise to heat our properties is mainly from burning fossil fuels that produces carbon dioxide (CO2). Therefore, if we can reduce the air leakage of a dwelling we reduce the energy consumption needed to heat the property to the same level we would find comfortable; saving money on bills and reducing carbon dioxide (CO2) emissions.

Why has air pressure testing been introduced?

In 2002, the Government released a White Paper with a target of reducing carbon dioxide (CO2) emissions by 20% from 1990 levels by 2010. To achieve these targets, sections of Building Regulations were modified, added to and revised.The Building Regulations 2006 Part L1a now makes it a compulsory legal requirement that new domestic dwellings must pass a mandatory airtightness test before becoming occupied.

What is air permeability or air infiltration?

These terms also refer to air leakage. This is the air tightness of a dwelling from uncontrolled and unplanned routes such as cracks and gaps in the dwellings construction. Any ventilation system installed in a building is seen as a source of controlled air flow and is therefore not considered as air leakage. This air leakage can often lead to unwanted draughts.

What is air pressure testing?

Air pressure testing is a method of measuring and quantifying the air leakage of a building. In Approved Document Part L1A of the Building Regulations, Air Tightness Testing is referred to as Pressure Testing. The test methodology for measuring the air tightness of a building is set out in ATTMA Technical Standard 1. Technical Standard 1 is generally based on BS EN Standard 13829:2001, Thermal Performance of Buildings – Determination of air permeability of buildings – Fan pressurisation method. Further information is available in TM23: Testing buildings for air leakage.

Why do I need to test the air tightness of a building?

Air pressure testing of a proportion of all new domestic housing is a legal requirement in accordance with the guidance given in Approved Document Part L1A – Conservation of fuel and power in new dwellings of the Building Regulations. Testing the air tightness of existing dwellings can highlight areas of problems that can be treated cost effectively to improve the energy efficiency of the dwelling as a whole.

When should air pressure testing be carried out?

Air leakage tests are generally carried out at the construction and commissioning stage of a dwelling when the external construction is fully complete. This is often referred to as the building envelope and does require for example all windows and doors to be in place, sealed and secured.

Can the property fail an air pressure test?

Yes. Guidance in the Government approved Document Part L1A sets out that failed dwelling types will require extra remedial work and retesting. On developments, one additional test would be required on another dwelling of the same property type. If the air pressure test does return a fail, it is possible to undertake a smoke test to help find the areas which are contributing to this.

Who can carry out air pressure tests?

Air pressure testing must be undertaken by a competent person. The British Institute of Non-Destructive Testing (BiNDT) runs a registration scheme of competent persons to ensure adherence to procedures, quality of service and UKAS calibration of equipment. BINDT administers the official scheme which is approved by The Department for Communities and Local Government (DCLG).