This test method provides a field procedure for determining the air leakage rates of installed exterior windows and doors. This test method is applicable to exterior windows and doors and is intended to measure only such leakage associated with the assembly and not the leakage through openings between the assemblies and adjacent construction. The test method can be adapted for the latter purpose, provided the potential paths of air movement and the sources of infiltration and exfiltration can be identified, controlled, or eliminated. This test method attempts to create and given set of natural environmental conditions. There is a strong possibility that the test method or the test apparatus may, by virtue of their design and use, induce air leakage that does not occur under natural environmental exposure. This test method is intended for the field testing of installed exterior windows or doors. Persons interested in laboratory testing of fenestration products should reference Test Method E283. Persons using this procedure should be knowledgeable in the area of fluid mechanics and instrumentation practices, and shall have a general understanding of fenestration products and components. Throughout this test method, SI units are listed first in accordance with E-6 metric policy, and shall be considered the primary units. Non-SI units are provided in parenthesis. This standard does not purport to address all of the safety problems, 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 precautionary statements, see Section 7.