Standard Test Method for Determining Air Leakage Rate by ...

1 Designation: E 779 03 Standard Test Method forDetermining Air Leakage Rate by Fan Pressurization1 This Standard is issued under the fixed designation E 779; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or This test Method covers a standardized technique formeasuring air- Leakage rates through a building envelope undercontrolled pressurization and This test Method is applicable to small temperaturedifferentials and low-wind pressure conditions. For tests con-ducted in the field, it must be recognized that field conditionsmay be less than ideal. Nevertheless, strong winds and largeindoor-outdoor temperature differentials should be This test Method is intended to produce a measure of airtightness of a building envelope.

2 This test Method does notmeasure air Leakage rates under normal conditions of weatherand building operation. To measure air-change rate directly, usethe tracer gas dilution Method (see Test Method E 741). This test Method is intended for the measurement of theairtightness of building envelopes of single-zone buildings. Forthe purpose of this test Method , many multi-zone buildings canbe treated as single-zone buildings by opening interior doors orby inducing equal pressures in adjacent Standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this Standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to specific hazardstatements see Section Referenced standards :2E 741 Test Method for Determining Air Change in a SingleZone by Means of a Tracer Gas 1258 Test Method for Airflow Calibration of Fan Pressur-ization Devices3.

3 Of Terms Specific to This rate,n air- Leakage rate in volume units/hdivided by the building space volume with identical volumeunits, normally expressed as air changes/h, ACT . graph,n the graph that shows the rela-tionship of measured airflow rates to the corresponding mea-sured pressure differences, usually plotted on a log-log rate,n the volume of air movement/unittime across the building This movement includes flow throughjoints, cracks, and porous surfaces, or a combination driving force for such an air Leakage , in service can beeither mechanical pressurization and de-pressurization, naturalwind pressures, or air temperature differentials between thebuilding interior and the outdoors, or a combination envelope,n the boundary or barrier sepa-rating the interior volume of a building from the For the purpose of this test Method , theinterior volume is the deliberately conditioned space within abuilding, generally not including attics, basements, and at-tached structures, for example, garages.

4 Unless such spaces areconnected to the heating and air conditioning system, such asa crawl space zone,n a space in which the pressure differ-ences between any two places, differ by no more than 5 % ofthe inside to outside pressure A multi-room space that is intercon-nected within itself with door-sized openings through anypartitions or floors is likely to satisfy this criterion if the fanairflow rate is less than 3 m3/s 63103ft3/min). pressure difference,n the measured pressuredifference across the building envelope, expressed in Pascals(in. of water or pounds-force/ft2or in. of mercury). and Units See Table Summary of Test This test Method consists of mechanical pressurizationor de-pressurization of a building and measurements of theresulting airflow rates at given indoor-outdoor static pressuredifferences. From the relationship between the airflow rates1 This test Method is under the jurisdiction of ASTM Committee E06 onPerformance of Buildings and is the direct responsibility of Subcommittee Air Leakage and edition approved Oct.

5 1, 2003. Published November 2003. Originallyapproved in 1981. Last previous edition approved in 1999 as E 779 referenced ASTM standards , visit the ASTM website, , orcontact ASTM Customer Service at ForAnnual Book of ASTMS tandardsvolume information, refer to the Standard s Document Summary page onthe ASTM ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United ASTM International Provided by IHS under license with ASTM Licensee=University of Texas Revised Sub Account/5620001114 Not for Resale, 04/14/2010 11:13:04 MDTNo reproduction or networking permitted without license from IHS--```,``,`````````,``,``,,```,,,-`-`, ,`,,`,`,,`---and pressure differences, the air Leakage characteristics of abuilding envelope can be Significance and Air Leakage accounts for a significant portion of thethermal space conditioning load. In addition, it can affectoccupant comfort and indoor air In most commercial or industrial buildings, outdoor airoften is introduced by design; however, air Leakage can be asignificant addition to the designed outdoor airflow.

6 In mostresidential buildings, indoor-outdoor air exchange is attribut-able primarily to air Leakage through cracks and constructionjoints and can be induced by pressure differences due totemperature differences, wind, operation of auxiliary fans, forexample, kitchen and bathroom exhausts, and the operation ofcombustion equipment in the The fan-pressurization Method is simpler than tracer gasmeasurements and is intended to characterize the air tightnessof the building envelope. It can be used to compare the relativeair tightness of several similar buildings, to identify the leakagesources and rates of Leakage from different components of thesame building envelope, and to determine the air leakagereduction for individual retrofit measures applied incrementallyto an existing building, and to determine ventilation rates whencombined with weather and leak location The following is a general description of the requiredapparatus.

7 Any arrangement of equipment using the sameprinciples and capable of performing the test procedure withinthe allowable tolerances is Equipment A fan, blower, or blowerdoor assembly that is capable of moving air into and out of theconditioned space at required flow rates under a range of testpressure differences. The system shall provide constant airflowat each incremental pressure difference at fixed pressure for theperiod required to obtain readings of airflow rate. Whereapplicable, the HVAC system of the building may be used inplace of the fan or Device A manometer or pres-sure indicator to measure pressure difference with an accuracyof65 % of measured Measuring System A device to measureairflow with an accuracy of65 % of the measured flow. Theairflow measuring system shall be calibrated in accordancewith Test Method E Device An instrument tomeasure temperature with an accuracy of61 C (2 F).

8 Speed-Measuring Device (Optional) A deviceto give an accuracy m/s ( mph) at m/s( mph). Perform wind speed measurements at a distancethree to five building heights away from the buildings, wherepractical. List the height above ground at which wind speed Protection Glass should not break at the buildingpressure differences normally applied to the test structure:however, for added safety, adequate precautions, such as theuse of eye protection should be taken to protect the Clothing Use safety equipment required forgeneral field work, including safety shoes, and hard Guards The air-moving equipment shallhave a proper guard or cage to house the fan or blower and toprevent accidental access to any moving parts of the Protection Make hearing protection availablefor personnel who must be close to the noise that may begenerated by the and Fumes The blower or fan forces a largevolume of air into or out of a building while in care not to damage plants, pets, occupants, or internalfurnishings due to influx of cold or warm air.

9 Exercise similarcautions against sucking debris or exhaust gases from fire-places and flues into the interior of the building. Activecombustion devices require a properly trained technician toshut them off or to determine the safety of conducting the To create a single zone for this test procedure, allinterconnecting doors, except for closets, which should beclosed, in the conditioned space should be opened such that auniform pressure will be maintained within the conditionedspace to within610 % of the measured inside/outside pressuredifference. Verify this condition by differential pressure mea-surements at the highest pressure used in the test. Make thesemeasurements at the highest and lowest level of the buildingand on the windward and leeward HVAC balancing dampers and registers should not beadjusted. Fireplace and other operable dampers should beclosed unless they are used to pass air to pressurize orde-pressurize the Make general observations of the condition of thebuilding.

10 Take notes on the windows, doors, opaque walls,roof, and Measure and record the indoor and outdoor tempera-tures at the beginning and the end of the test so that theiraverage values can be estimated. If the product of the absolutevalue of the indoor/outdoor air temperature difference multi-plied by the building height, gives a result greater than 200m C (1180 ft F), do not perform the test, because the pressuredifference induced by the stack effect is too large to allowaccurate interpretation of the 1 Symbols and UnitsSymbolQuantityUnitEElevation above sea levelm [ft]QMeasured airflow ratem3/s [cfm]QoAir Leakage ratem3/s [cfm]CAir Leakage coefficientm3/(s Pan) [cfm/Pan]rAir densitykg/m3[lb/ft3]TTemperature C [ F]nPressure exponent..PPressurePa [lb/ft2]dPInduced pressure differencePa [lb/ft2]dPrReference pressure differencePa [lb/ft2] Dynamic air viscositykg/(m s) [lb/(ft h)]AAream2[ft2]E779 032 Copyright ASTM International Provided by IHS under license with ASTM Licensee=University of Texas Revised Sub Account/5620001114 Not for Resale, 04/14/2010 11:13:04 MDTNo reproduction or networking permitted without license from IHS--```,``,`````````,``,``,,```,,,-`-`, ,`,,`,`,,` If the wind speed is to be part of the measurementrecord, use a wind-measuring device or obtain readings from anearby weather bureau.