Air leakage describes the uncontrolled movement of air into and out of a building. Because warm air rises it will try to find it's way out of a building as quickly as it can therefore drawing cold air in from outside. The more air tight a building is the less often the air changes within it and so less energy is required to maintain warmth inside it. A building must of course be allowed to breath to a certain extent but the test is in place to ensure that ventilation is controllable. UK building regulations now specify that all new homes meet a certain level of air tightness as specified in it's 'SAP' calculations. Anglia Air Testing can carry out air tests to establish air leakage on a completed structure, and supply the required certification to obtain Local Authority Building Control Approval.

Firstly the 'blower door' assembly is installed in one of the external doors. An air tight screen is fitted over an adjustable frame (pictured top right). A large electric fan is then fitted in to the frame. All windows, doors and vents are closed before the test, anything that cannot be closed is temporarily sealed, such as extractors or fireplaces. The test works by using the fan to generate a specific pressure within the building. As it does this, air from outside will be drawn into the house via any gaps in it's outer shell. The test equipment can measure the leakage by monitoring the air flow required to create specific pressure levels. Currently the maximum amount of leakage allowed by the regulations is 10 cubic metres per hour measured against the building's surface area at a pressure of 50 pascals.

Anglia Air Testing Ltd, Clayland House, 1 Norwich Road, Watton Norfolk IP25 6DA

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