5.1 Air infiltration into the conditioned space of a building accounts for a significant portion of the thermal space condition load. Air infiltration can affect occupant comfort by producing drafts, cause indoor air quality problems by carrying outdoor pollutants into occupied building space and, in hot humid climates, can deposit moisture in the building envelope resulting in deterioration of building envelope components. In cold climates, exfiltration of conditioned air out of a building can deposit moisture in the building envelope causing deterioration of building envelope components. Differential pressure across the building envelope and the presence of air leakage sites cause air infiltration and exfiltration (1).4

5.2 Where restricting air movement between interior zones of a building is desired to separate dissimilar interior environments or prevent the movement of pollutants, the detection practices presented are useful in detecting air leaks between interior zones of the building.

5.3 Where practices require controlled flow direction, forced pressurization or depressurization shall be used.

Note 2: Forced air leakage is required because air leakage sites are often difficult to locate because air flows may be small under the prevailing weather conditions. Wind conditions can aid in air leakage detection by forcing air to enter a building; however, where air is exiting, the building envelope construction may make observations difficult.

5.4 The techniques for air leakage site detection covered in these practices allow for a wide range of flexibility in the choice of techniques that are best suited for detecting various types of air leakage sites in specific situations.

5.5 The infrared scanning technique for air leakage site detection has the advantage of rapid surveying capability. Entire building exterior surfaces or inside wall surfaces are covered with a single scan or a simple scanning action, provided there are no obscuring thermal effects from construction features or incident solar radiation. The details of a specific air leakage site are then probed more closely by focusing on the local area. Local leak detection is well addressed with the smoke tracer, theatrical fog, anemometer, sound detection, the bubble detection, and the tracer gas techniques, however these techniques are time consuming for large surfaces. The pressurized or depressurized test chamber and smoke tracer or a depressurized test chamber and leak detection liquid practices are used in situations where depressurizing or pressurizing the entire envelope is impractical, such as is the case during construction. Both of the practices enable the detection of very small leaks. To perform these practices requires that the air barrier system is accessible.

5.6 Complexity of building air leakage sites diminishes the ability for detection. For example, using the sound detection approach, sound is absorbed in the tortuous path through the insulation. Air moving through such building leakage paths loses some of its temperature differential and thus make thermographic detection difficult. The absence of jet-like air flow at an air leakage site makes detection using the anemometer practice difficult.

5.7 Stack effect in multistory commercial buildings can cause gravity dampers to stand open. Computer-controlled dampers shall be placed in normal and night modes to aid in determining the conditions existing in the building. Sensitive pressure measurement equipment is used for evaluating pressure levels between floors and the exterior.

1.1 These practices cover standardized techniques for locating air leakage sites in building envelopes and air barrier systems.

1.2 Individual practices provide advantages for specific applications.

1.3 Some of the practices require a knowledge of infrared scanning, building and test chamber pressurization and depressurization, smoke and fog generation techniques, sound generation and detection, and tracer gas concentration measurement techniques.

1.4 The practices described are of a qualitative nature in determining the air leakage sites rather than determining quantitative leakage rates.

1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.6 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use. For specific hazard statements, see Section 6.

1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.