1、Designation: E3054/E3054M 16Standard Guide forCharacterization and Use of Hygrothermal Models forMoisture Control Design in Building Envelopes1This standard is issued under the fixed designation E3054/E3054M; the number immediately following the designation indicates the yearof original adoption or,
2、 in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval.A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This guide offers guidance for the characterization anduse of hygrothermal model
3、s for moisture control design ofbuilding envelopes. In this context, “hygrothermal models”refers to the application of a mathematical model to thesolution of a specific heat and moisture flow performance issueor problem. Hygrothermal models are used to predict andevaluate design considerations for t
4、he short-term and long-termthermal and moisture performance of building envelopes.1.2 Each hygrothermal model has specific capabilities andlimitations. Determining the most appropriate hygrothermalmodel for a particular application requires a thorough analysisof the problem at hand, understanding th
5、e required transportprocesses involved, and available resources to conduct theanalysis. Users of this guide can describe the functionality ofthe hygrothermal model used in an analysis in a consistentmanner.1.3 This guide applies to hygrothermal models that rangefrom complex research tools to simple
6、design tools. This guideprovides a protocol for matching the analysis needs and thecapabilities of candidate models.1.4 This guide applies to the use of models that include allor part of the following thermal and moisture storage andtransport phenomena: (1) heat storage of dry and wet buildingmateri
7、als, (2) heat transport by moisture-dependant thermalconduction, (3) phase change phenomena (for example, evapo-ration and condensation), (4) heat transport by air convection,(5) moisture retention by vapor adsorption and capillary forces,(6) moisture transport by vapor diffusion (molecular andeffus
8、ion), (7) moisture transport by liquid transport (surfacediffusion and capillary flow), and (8) moisture (vapor) trans-port by air convection.1.5 This guide does not apply to cases requiring analysis ofthe following: (1) convection that occurs in a three-dimensional manner or through holes and crack
9、s; (2) hydraulic,osmotic, or electrophoretic forces; (3) salt or other solutetransport; or (4) material properties that change with age.1.6 This guide intends to provide guidance regarding reli-ability of input and how the corresponding results can beaffected as well as a format for determining such
10、 information.1.7 UnitsThe values stated in either SI units or inch-pound units are to be regarded separately as standard. Thevalues stated in each system may not be exact equivalents;therefore, each system shall be used independently of the other.Combining values from the two systems may result in n
11、on-conformance with the standard.1.8 This guide offers an organized characterization ofhygrothermal models and does not recommend a specificcourse of action. This document cannot replace education orexperience and should be used in conjunction with professionaljudgment. Not all aspects of this guide
12、 may be applicable in allcircumstances. This ASTM standard is not intended to repre-sent or replace the standard of care by which the adequacy ofa given professional service must be judged, nor should thisdocument be applied without consideration of a projects manyunique aspects. The word “Standard”
13、 in the title of thisdocument means only that the document has been approvedthrough the ASTM International consensus process.1.9 This 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 app
14、ro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C168 Terminology Relating to Thermal InsulationE283 Test Method for Determining Rate of Air LeakageThrough Exterior Windows, Curtain Walls, and Doo
15、rsUnder Specified Pressure Differences Across the Speci-men1This guide is under the jurisdiction of ASTM Committee E06 on Performanceof Buildings and is the direct responsibility of Subcommittee E06.41 on AirLeakage and Ventilation Performance.Current edition approved March 15, 2016. Published May 2
16、016. DOI: 10.1520/E3054_E3054M-16.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM Internationa
17、l, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1E331 Test Method for Water Penetration of ExteriorWindows, Skylights, Doors, and Curtain Walls by Uni-form Static Air Pressure DifferenceE631 Terminology of Building ConstructionsE2273 Test Method for Determining
18、the Drainage Efficiencyof Exterior Insulation and Finish Systems (EIFS) CladWall AssembliesE2357 Test Method for Determining Air Leakage of AirBarrier Assemblies2.2 Other Standards:ANSI/ASHRAE 160-2009 Criteria for Moisture-ControlDesign Analysis in Buildings3DIN EN 15026 Hygrothermal performance of
19、 building com-ponents and building elements - Assessment of moisturetransfer by numerical simulation4WTA Guideline 6-2-01 Simulation of Heat and MoistureTransfer53. Terminology3.1 Definitions: For definitions of terms used in this guide,see Terminologies C168 and E631.3.2 Definitions of Terms Specif
20、ic to This Standard:3.2.1 air-leakage rate, nvolume of air movement per unittime across the building envelope.3.2.1.1 Discussionthis movement includes flow throughjoints, cracks, and porous surfaces, or a combination thereof.The driving force for such an air leakage in service can bemechanical press
21、urization and depressurization, natural windpressures, or air temperature differentials between the buildinginterior and the outdoors, or a combination thereof.3.2.2 analytical model, nmodel that uses closed formsolutions to the governing equations applicable to hygrother-mal flow and transport proc
22、esses.3.2.3 building envelope, nboundary or barrier separatingthe interior volume of a building from the outside environmentor different interior environment.3.2.3.1 DiscussionFor the purpose of this guide, theinterior volume is the deliberately conditioned space within abuilding, generally not incl
23、uding attics, basements, and at-tached structures, for example, garages, unless such spaces areconnected to the heating and air conditioning system, such asa crawl space plenum. The outside environment may beweather conditions or any other known conditions that theexterior of the building envelope i
24、s exposed to. An interiorpartition that separates two dissimilar environments such as acold storage facility adjacent to an occupied office can betreated as a building envelope element for the modelingpurposes.3.2.4 building envelope model, nportion of the buildingenvelope, such as a wall, roof, flo
25、or, window, or door, or acombination thereof. The building envelope model comprisesall of the components and materials as they are configuredwithin the buidling envelope assembly (for example, the wallor roof assembly) at a given location.3.2.5 computer code (computer program), nassembly ofnumerical
26、 techniques, bookkeeping, and control language thatrepresents the model from acceptance of input data andinstructions to delivery of output.3.2.6 conceptual model, ninterpretation or working de-scription of the characteristics and dynamics of the physicalsystem.3.2.7 finite difference model, ntype o
27、f approximate, nu-merical model that uses a discretization technique to linearizethe governing partial differential equations (PDE) consisting ofreplacing the continuous domain of interest by a finite array ofspaced mesh or grid points (that is, nodes) spaced along thecoordinate direction(s) of the
28、one-, two-, or three-dimensionalgeometric coordinate system. The grid points define a set ofcontrol volumes representing volume-averaged subdomainproperties. The derivatives of the PDE for each of these pointsare approximated using finite differences. The resulting set oflinear or nonlinear algebrai
29、c equations are solved using director iterative matrix-solving techniques.3.2.8 finite element model, ntype of approximate, numeri-cal model that uses a discrete technique for solving thegoverning PDE wherein the domain of interest is representedby a finite number of mesh or grid points (that is, no
30、des),information between these points is obtained by interpolationusing piecewise continuous polynomials, and the resulting setof linear or nonlinear algebraic equations is solved using director iterative matrix-solving techniques.3.2.9 functionality, nof a hygrothermal model, the set offunctions an
31、d features the model offers the user in terms ofbuilding envelope framework geometry, simulated processes,initial and boundary conditions, and analytical and operationalcapabilities.3.2.10 hygrothermal model, na mathematical model thatincludes various thermal and moisture transport mechanismswith bo
32、undary system performance under applied conditions torepresent a building envelope system or subsystem.3.2.10.1 DiscussionMay be either steady-state or transientapproach and may be based on equations derived from basicprinciples of physics, established engineering functionalrelationships, statistica
33、l interpretations of empirical data, or acombination of all of these approaches.3.2.11 hygrothermal model code, ncomputer code used inhygrothermal modeling to represent a non-unique, simplifiedmathematical description of the physical framework, geometry,active processes, and initial and boundary con
34、ditions present ina building system.3.2.12 model selection, nprocess of choosing the appro-priate computer model as an analysis tool capable of simulatingthose characteristics of the physical system required to fulfillthe projects objective(s).3.2.13 Moisture Reference Year, MRYa year of hourlyweath
35、er data that have been selected for use in hygrothermalanalysis.3Available from American Society of Heating, Refrigerating, and Air-Conditioning Engineers, Inc. (ASHRAE), 1791 Tullie Circle, NE, Atlanta, GA30329, http:/www.ashrae.org.4Available from Deutsches Institut fr Normung e.V.(DIN), Am DIN-Pl
36、atz,Burggrafenstrasse 6, 10787 Berlin, Germany, http:/www.din.de.5Available from WTA-Publications, Ingolstdter Strae 102, D-85276Pfaffenhofen, Germany, http:/www.wta-international.org/?L=2.E3054/E3054M 1623.2.14 numerical model, nmodel that uses numericalmethods to solve the governing equations of t
37、he applicableproblem.3.2.15 water penetration, na process in which water gainsaccess into a material or system by passing through the surfaceexposed to the water.3.2.15.1 DiscussionFor products with non-planar glazingsurfaces (domes, vaults, pyramids, and so forth), the planedefining water penetrati
38、on is the plane defined by the innermostedges of the unit frame.3.3 Symbols:qv= mass flux rate of vapor flow (kg/m2s lb/ft2s)X = vapor concentration (kg/m3lb/ft3)p= water vapor permeability (kg/Pams Perm-in)he= specific latent heat of evaporation or condensation(J/kg Btu/lb)gair= air mass flux (kg/m
39、2s lb/ft2s) = thermal conductivity (W/mK Btu/hftF)mdry= mass of dry material (kg lb)mwet= mass of wet material (kg lb)Pair= air pressure (Pa psi)Pe= exterior air pressure (Pa psi)Pi= interior pressure (Pa psi)w= density of water (kg/m3lb/ft3)s= dry density of material (kg/m3lb/ft3)air= dry density o
40、f material (kg/m3lb/ft3)cw= specific heat capacity of liquid water (J/kgKBtu lbF)cs= specific heat capacity of dry material (J/kgKBtu lbF)ca= specific heat capacity of dry air (J/kgK Btu/lbF) = dynamic viscosity (sPa lbs/ft2)ka= air permeability (m2ft2)T = temperature (K F) = relative humidity (-)ql
41、= liquid transport flow (kg/m2s lb/ft2s)u = moisture content (kg/kg lb/lb)t = time (s) (s)x = xcoordinateD= liquid conduction coefficient (kg/ms lb/fts)4. Significance and Use4.1 This guide is intended to provide the framework forcharacterizing the functions of the hygrothermal model and thelevel of
42、 sophistication used as inputs for each analysis.Hygrothermal modeling has become an important practice insupport of the decision-making design processes involved inmoisture management of building envelope systems.Increasingly, hygrothermal models are an integral part ofbuilding envelope performance
43、 assessment, retrofit, and resto-ration studies and provide insight in the screening of alternativedesign approaches affecting water management of the envelopesystem. Hygrothermal models are used in decision makingduring the design process of building envelope systems. Theymay also be used to assess
44、 performance of the envelopes ofexisting buildings, or to predict envelope performance inbuildings undergoing retrofit, change in use, restoration orflood remediation. It is, therefore, important to have a meth-odology to document the model used in a hygrothermalinvestigation. This documentation pro
45、vides needed character-ization of the hygrothermal model to assess its credibility andsuitability. This becomes even more important because of theincreasing complexity of the building envelope systems forwhich new hygrothermal models are being developed. Thereare many different hygrothermal models a
46、vailable, each withspecific capabilities, operational characteristics, and limita-tions. If modeling is considered for a project, it is important todetermine if a hygrothermal model is appropriate for thatproject, or if a model exists that can perform the simulationsrequired in the project.4.2 Quali
47、ty assurance in a hygrothermal analysis usingmodeling is achieved by using the most appropriate model withall important transport mechanisms, initial conditions, andboundary conditions. A well-executed quality assurance pro-gram in hygrothermal modeling requires systematic and com-plete documentatio
48、n of the model and the inputs followed byconsistent reporting of the results. This guide sets forth aformat for reporting hygrothermal modeling results.5. Hygrothermal Model Analysis Inputs5.1 There are many hygrothermal models available tosimulate, describe, or analyze different building envelopesy
49、stems and the moisture migration characteristics that affecttheir performance. Therefore, it is important to understand theperformance characteristics for which the model is intended torepresent and recognize the evaluation of the model is onlyrelevant for the performance characteristics it addresses. If theappropriate analytical and input techniques are applied to themodel, then the results obtained should provide a valid solutionto address the system deficiencies. Fig. 1 displays the va
