Fan Pressurization Method to Measure House Leakage Area Using Built-in Exhaust Fans and Window Openings as Reference Areas

The fan pressurization method described in ISO 9972:2015 evaluates the air permeability of houses by measuring the effective leakage area. This method uses a specialized blower equipped with a volumetric airflow meter and a differential pressure sensor. This study proposes an alternative that utilizes a differential pressure sensor along with household exhaust fans to depressurize a house. Additionally, the known area of an open house window is used to calibrate the effective leakage area against the corresponding geometrical area. To validate this method, the relationship between the geometric leakage area and the effective leakage area obtained through this approach, as well as comparisons with other methods, were examined via theoretical analysis and experiments in a small container space. In a single room in an actual building characterized by substantial leakage gaps, such as those around interior doors, the total leakage area measured with a gap meter was 311.5 cm², and the proposed method yielded the same value, demonstrating excellent agreement between the two. The proposed method was tested in a 36-year-old American-style house with a total floor area of 226.59 m² and resulted in an effective leakage area of 672 cm² and a C-value of 2.96 cm²/m². The geometrically measurable leakage area and the area estimated using the proposed method showed good agreement, confirming the reliability of the approach. Furthermore, the C-value of 2.96 cm²/m², derived from the effective leakage area measured in an actual house experiment, falls within the typical range for residential buildings (1–10 cm²/m²).