5.1 This test method is a standard procedure for determining the air leakage characteristics of installed exterior windows and doors under specified static air pressure differences.

Note 1: The air pressure differences acting across a building envelope vary greatly. The factors affecting air pressure differences and the implications of the resulting air leakage relative to the environment within buildings are discussed in the literature.3^, 4^, 5 These factors should be fully considered in specifying the test pressure differences to be used.

5.2 Rates of air leakage are sometimes used for comparison purposes. Such comparisons may not be valid unless the components being tested and compared are of essentially the same size, configuration, and design.

5.3 Rates of air leakage of essentially identical windows or doors, as determined in the laboratory (Test Method E283) and as measured in the field by this test method, have sometimes been used for comparison purposes. The correlation between the laboratory and field test results, and the correlation between actual performance of in-service products and the response to these tests has not been established because of insufficient data.

5.4 Rates of air leakage, as determined by this test method may be affected by: the age or physical condition of the test specimen; the type or quality of installation; the care exercised in the attachment of the test apparatus and the determination of extraneous leakage; and the actual conditions to which the test specimen is exposed beyond those imposed by the test method, that is temperature, relative humidity, wind impingement, etc. Consideration must be given to the proper selection of test specimens, the choice of appropriate test technique (when a choice is given within this test method), and the proper use and interpretation of the results obtained from this test to minimize the effect of these conditions.

5.5 Rates of air leakage, as determined by this test method may include air leakage that does not occur during normal operation and exposure, or that does not contribute to the overall air leakage for the structure. Air may be supplied to or exhausted from wall cavities or adjacent construction, or may bypass interior or exterior trim or components in a manner not experienced during normal operation or exposure. Care must be taken to prevent such leakage from occurring, or consideration must be given that such leakage may have occurred during the test.

5.6 This test method addresses the issue of air leakage through the high pressure face of the test specimen only. Air leakage from the adjacent wall cavity through sill, head, and jambs of the window frame is considered extraneous air leakage and, therefore, not a component of the measured specimen air leakage. Such extraneous air leakage through the perimeter frame of the test specimen can be a significant source of air leakage into, or out of, the building if the frame is not sealed against air infiltration from the adjacent wall cavity.