What is Air Leakage?

What is Air Leakage?

Air leakage is where conditioned air enters and leaves a building uncontrollably through cracks and holes. It is also known as infiltration and is totally different to ventilation, which is fresh air that enters a building in a controlled manner to exhaust excess moisture and reduce odours and stuffiness.

As Air Leakage is uncontrolled, too much air may enter the house during cold or windy weather, leading to excessive heat loss and the uncomfortable feeling of cold draughts.

Air Leakage plays a major part in the energy efficiency of buildings, and testing is necessary as a means of demonstrating that the air tightness targets used in building energy calculations have been achieved in reality.

In England and Wales, Air Tightness Testing has been mandatory since the 2006 Building Regulations for most dwellings and commercial projects.

Why test for Airtightness?

Airtightness is a key factor in building energy efficiency, and consequently is a feature of Government led initiatives to combat climate change through improvements in building energy performance. Heating buildings involves burning fossil fuels which contribute towards CO2 emissions and global warming. Reducing air leakage results in less heat loss, which in turn reduces the amount a heating system must be used.

There are also health issues around airtightness – when a building has poor levels of controlled ventilation and high levels of uncontrolled air leakage this can cause excessive moisture and mould growth which can affect the occupier’s health. Best practice advice is “Build tight, ventilate right”.

Finally, high levels of air leakage can lead to moisture ingress into the building fabric, potentially resulting in very expensive repair costs.

Who do the regulations affect?

The testing and subsequent targets for air leakage has been gradually phased in to cover just about all new-build developments.

In 2002 Building Regulations only required commercial and industrial buildings with a gross floor area greater than 1000 m2 to be tested for airtightness. In 2006 this was extended via Approved Document L2A of the Building Regulations to cover all sizes of commercial and industrial buildings, and Approved Document L1A which introduced testing of new dwellings.

Are there any exceptions?

There are some buildings such as agricultural buildings that are exempt from Building Regulations altogether, plus buildings that have a planned time of use of less that two years are exempt from energy efficiency requirements.

For non-dwellings there are a few exceptions:

  • Buildings under 500m2

  • Factory-made modular buildings where a regime of type testing has already been carried out

  • Large extensions where sealing off the extension from the existing building would be difficult

  • Complex buildings where the airtightness testing would be impractical such as airport terminals

  • Compartmentalised buildings that cannot be tested as one single entity – a representative of the building would need to be tested

For dwellings, if a whole development is being built then only a sample need to be tested and Approved Document L1A sets out rules for this.

Passing the air leakage test

At Energytest we are registered members of Air Tightness Measurement Association (ATTMA) and have a team of experienced test engineers for both commercial and domestic developments that can help you meet the correct target. By using an ATTMA registered testing company such as Energytest you can be guaranteed that the air leakage test certificate we issue will be accepted by Building Control as evidence of Building Regulations sign off. Our consultants will be on hand throughout the construction process offering free advice and guidance.