A Negative Pressure Test, also known as a depressurisation test or a blower door test, is a diagnostic procedure used to measure the airtightness of a building or a specific area within a building. It involves creating a pressure differential between the inside and outside of the building by depressurising the interior using a blower door.
During the test, a blower door fan is installed in an exterior door or opening, and the fan is used to draw air out of the building, creating a negative pressure inside. This negative pressure exaggerates the potential for air leakage, allowing for the detection and quantification of any uncontrolled airflow paths.
By measuring the airflow rate required to maintain the desired pressure difference, the test can provide information about the air leakage rate of the building. The results are typically reported as the air changes per hour (ACH) or the Leakage Rate Index (LRI), which represents the volume of air that leaks in or out of the building per hour per unit of building envelope area.
Negative Pressure Testing is commonly used in energy audits, airtightness assessments, and building performance evaluations. It helps identify areas of air leakage, locate potential sources of energy loss, and guide targeted air sealing efforts. By improving a building’s airtightness based on the findings of a negative pressure test, energy efficiency can be enhanced, and indoor comfort can be improved.