Blowerdoortest

Blowerdoortest is a diagnostic method used to quantify the airtightness of a building. In Dutch, the term blowerdoortest refers to the blower door test, which measures the rate at which air leaks through the building envelope by installing a calibrated fan in an exterior door or window and creating a controlled pressure difference between the inside and outside, typically 50 pascals. All interior doors and large openings are closed, HVAC systems may be shut off, and any intentional exhaust fans may be turned off. The airflow required to maintain the specified pressure is recorded and used to calculate the air leakage rate, reported as air changes per hour at 50 Pa (ACH50). Some protocols also report leakage at different pressures or the overall leakage in cubic meters per hour per square meter (m3/h·m2). The test helps assess energy efficiency, identify leaks for targeted sealing, and verify compliance with energy performance standards and building codes.

In Europe, tests follow standards such as ISO 9972 and EN 13829; in the United States, procedures are described in ASTM E779. Results inform energy audits, retrofit planning, and certification programs such as Passive House. Limitations include dependence on weather conditions, wind effects, and the presence of mechanical ventilation; the test assesses envelope leakage rather than the performance of active HVAC systems and may require conditions that differ from normal occupancy. The blowerdoortest is commonly applied to new construction and existing buildings undergoing energy retrofits.