Blower Door Airtightness Test Setup
Blower door apparatus installed in a residential property's external doorway to conduct an airtightness test.
This image shows a blower door testing rig installed in the front door frame of a residential property. The bright red fabric panel seals the doorway, while the built-in fan is used to pressurise or depressurise the building to measure overall air leakage rates. Blue tape is also visible, temporarily sealing a nearby window vent during the test.
Technical insight
A blower door test is a diagnostic procedure used to measure the airtightness of a building envelope. By installing a specialised fan into an external doorway and sealing the remaining opening with a flexible panel, technicians can safely pressurise or depressurise the property. This controlled pressure difference forces air through any unsealed gaps, cracks, or structural penetrations. Identifying and quantifying these uncontrolled air leakages is a critical step in energy retrofits, as unwanted draughts significantly contribute to heat loss, poor indoor comfort, and energy inefficiency. Once located, these pathways can be targeted with appropriate draught-proofing and sealing measures.
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