What is Air Leakage?

Leakage is the uncontrolled flow of air through gaps, cracks and holes in the fabric of a building, which may not be visible to the naked eye. This is not ventilation systems, as this is 'controlled' movement of air.

Air leakage is caused by 3 main forces:

• Wind- Wind changes, result in changes to the pressure that is exerted on a building.
• Stack Effect- This is the process of warm air rising through the building envelope, which causes air to be pulled through the fabric of the building envelope
• Mechanical Systems- Heating and ventilation systems have positive and negative effects on the pressure in a building.

Why do we need Air Testing?

Part L1A is an amendment that has been made to the Building Regulations, of new houses and large extensions (25%+ of existing).

An air test rating is now mandatory in order to comply with this regulation; the rate your property will need to achieve will be determined in your Target Emission Rate (TER).

Building Control will not provide a completion certificate without the necessary Air Testing results and report.

Where the 'Approved Construction' details have been adopted one test should be carried out on EACH dwelling TYPE. The following constitutes a change in dwelling type:

• Change in method of build i.e timber frame, brick and block.
• Ground floor, mid floor and top floor flats.
• End terrace and mid terrace.
• Semi detached and detached
• a 15% difference in floor area

Note: One block of flats is treated as one development, so each block will require testing.

What are the positive affects of Air Leakage control?

• Presents a Unique Selling Point for the developer!
• Fundamentally for the consumer, heating bills will be reduced considerably.
• 47% of the UK's CO2 emissions are from homes, this will drop dramatically.
• Tests relate 'draughty' houses to illness and discomfort for the consumer.
• Reduces noise transfer through the leakage paths
• Helps prevent decline of the building fabric due to interstitial condensation.