What is a blower door test?
A blower door is a calibrated fan temporarily installed in an exterior doorway. The fan changes the pressure inside the building, allowing the amount of air leakage through the building enclosure to be measured.
What happens during the test?
- Exterior windows and doors are closed.
- The testing fan is installed in an exterior doorway.
- The fan creates a controlled pressure difference.
- Airflow measurements are recorded.
- The results are used to calculate airtightness.
What does ACH50 mean?
ACH50 means air changes per hour at a pressure difference of 50 pascals. A lower ACH50 result generally indicates a more airtight building enclosure.
Why does airtightness matter?
Better control of air leakage can reduce drafts, lower heating and cooling demand, and help the ventilation system operate as intended.
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