The purpose of this test procedure is to measure the air leakage rate through a building envelope.

1. This enclosure leakage procedure is applicable to nonresidential buildings.
   1. Buildings that have less than 10,000 ft² of conditioned floor area may perform the whole-building air leakage test in accordance with Residential Energy Services Network (RESNET)/ANSI/ICC3 380-2019 Guidelines and RA3.8 rather than those in NA5.2-7.
   2. Buildings that have more than 50,000 ft² of conditioned floor area, a sectional test method of co-pressurizing representative test floors and taking data from the specific floors is permitted when following the procedures in Sections NA5.2-7. Representative test floors must meet the following conditions as adopted from ASHRAE 90.1-2019 Exceptions to 5.4.3.1.1:
      1. The entire floor area of all stories that have any spaces directly under a roof.
      2. The entire floor area of all stories that have a building entrance or loading dock.
      3. Representative above-grade wall sections of the building totaling at least 25% of the wall area enclosing the remaining conditioned space. Floor areas in parts a) and b) shall not be included in the 25%.
      4. When interpreting the data and determining the final air leakage rate, the measured air leakage is area-weighted by the surface areas of the building envelope.
2. The measurement procedure shall be based on the specifications of ASTM E3158 by blower door fan assembly (architectural only) and multi-point regression testing as further specified in Sections NA5.2, NA5.3, NA5.4, NA5.5, NA5.6, NA5.7 below.