Air leakage accounts for a significant portion of the thermal space conditioning load. In addition, it can affect occupant comfort and indoor air quality.

In most commercial or industrial buildings, outdoor air often is introduced by design; however, air leakage can be a significant addition to the designed outdoor airflow. In most residential buildings, indoor-outdoor air exchange is attributable primarily to air leakage through cracks and construction joints and can be induced by pressure differences due to temperature differences, wind, operation of auxiliary fans, for example, kitchen and bathroom exhausts, and the operation of combustion equipment in the building.

The fan-pressurization method is simpler than tracer gas measurements and is intended to characterize the air tightness of the building envelope. It can be used to compare the relative air tightness of several similar buildings, to identify the leakage sources and rates of leakage from different components of the same building envelope, and to determine the air leakage reduction for individual retrofit measures applied incrementally to an existing building, and to determine ventilation rates when combined with weather and leak location information.

1.1 This test method covers a standardized technique for measuring air-leakage rates through a building envelope under controlled pressurization and de-pressurization.

1.2 This test method is applicable to small temperature differentials and low-wind pressure conditions. For tests conducted in the field, it must be recognized that field conditions may be less than ideal. Nevertheless, strong winds and large indoor-outdoor temperature differentials should be avoided.

1.3 This test method is intended to produce a measure of air tightness of a building envelope. This test method does not measure air leakage rates under normal conditions of weather and building operation. To measure air-change rate directly, use the tracer gas dilution method (see Test Method E 741).

1.4 This test method is intended for the measurement of the airtightness of building envelopes of single-zone buildings. For the purpose of this test method, many multi-zone buildings can be treated as single-zone buildings by opening interior doors or by inducing equal pressures in adjacent zones.

1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific hazard statements see Section 7.