Large compartmentalization testing, also known as whole-building blower door testing or building enclosure leakage testing, is a specialized diagnostic process used to evaluate the airtightness and integrity of large commercial, industrial, and multifamily structures. The purpose of this testing is to measure uncontrolled air leakage through the building envelope, helping owners, developers, and contractors identify deficiencies that may impact energy efficiency, indoor environmental quality, occupant comfort, moisture control, and long-term building performance.

Large compartmentalization testing is typically conducted in accordance with recognized industry standards such as ASTM E779, E1827, E3158, and other applicable building enclosure testing protocols. The collected data provides measurable performance metrics such as airflow rates, pressure relationships, and air changes per hour (ACH), which can then be compared against project specifications, code requirements, or industry benchmarks. Infrared thermography and diagnostic inspections are often performed alongside blower door testing to identify leakage pathways that may not be visually apparent.

The benefits of the test extend beyond compliance. Properly sealed buildings can reduce energy consumption, enhance indoor air quality, protect sensitive equipment, and improve overall operational efficiency.