1、 g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58and building elements Assessment of moisture transfer by numerical simulationThe European Standard
2、EN 15026:2007 has the status of a British StandardICS 91.120.10; 91.080.01Hygrothermal performance of building components BRITISH STANDARDBS EN 15026:2007BS EN 15026:2007This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 August 2007 BSI 2007I
3、SBN 978 0 580 54741 6Amendments issued since publicationAmd. No. Date CommentsCompliance with a British Standard cannot confer immunity from legal obligations.National forewordThis British Standard is the UK implementation of EN 15026:2007.The UK participation in its preparation was entrusted to Tec
4、hnical Committee B/540, Energy performance of materials components and buildings.A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its co
5、rrect application.EUROPEAN STANDARDNORME EUROPENNEEUROPISCHE NORMEN 15026April 2007ICS 91.080.01English VersionHygrothermal performance of building components and buildingelements - Assessment of moisture transfer by numericalsimulationPerformance hygrothermique des composants et parois debtiments -
6、 Evaluation du transfert dhumidit parsimulation numriqueWrme- und feuchtetechnisches Verhalten von Bauteilenund Bauelementen - Bewertung der Feuchtebertragungdurch numerische SimulationThis European Standard was approved by CEN on 28 February 2007.CEN members are bound to comply with the CEN/CENELEC
7、 Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the CEN Management Centre or to any CEN
8、member.This European Standard exists in three official versions (English, French, German). A version in any other language made by translationunder the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as theofficial versions.CEN membe
9、rs are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,Romania, Slovakia, Slovenia, Spain, Sweden, Swi
10、tzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMIT EUROPEN DE NORMALISATIONEUROPISCHES KOMITEE FR NORMUNGManagement Centre: rue de Stassart, 36 B-1050 Brussels 2007 CEN All rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN
11、 15026:2007: EEN 15026:2007 (E) 2 Contents Page Foreword3 Introduction .4 1 Scope 5 2 Normative references 6 3 Terms, definitions, symbols and units 6 3.1 Terms and definitions .6 3.2 Symbols and units.6 4 Hygrothermal equations and material properties 8 4.1 Assumptions 8 4.2 Transport of heat and m
12、oisture9 4.3 Material properties.11 5 Boundary conditions.13 5.1 Internal conditions.13 5.2 External conditions14 6 Documentation of input data and results15 6.1 General15 6.2 Problem description 15 6.3 Hygrothermal model and numerical solution .16 6.4 Calculation report 16 Annex A (normative) Bench
13、mark example Moisture uptake in a semi-infinite region .18 A.1 General18 A.2 Problem description 18 A.3 Results 19 Annex B (informative) Design of Moisture Reference Years 22 Annex C (informative) Internal boundary conditions 23 Bibliography 24 EN 15026:2007 (E) 3 Foreword This document (EN 15026:20
14、07) has been prepared by Technical Committee CEN/TC 89 “Thermal performance of buildings and building components”, the secretariat of which is held by SIS. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the la
15、test by October 2007, and conflicting national standards shall be withdrawn at the latest by October 2007. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard : Austria, Belgium, Bulgaria, Cy
16、prus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EN 15026:2007 (E) 4 Introduction This s
17、tandard defines the practical application of hygrothermal simulation software used to predict one-dimensional transient heat and moisture transfer in multi-layer building envelope components subjected to non steady climate conditions on either side. In contrast to the steady-state assessment of inte
18、rstitial condensation by the Glaser method (as described in EN ISO 13788), transient hygrothermal simulation provides more detailed and accurate information on the risk of moisture problems within building components and on the design of remedial treatment. While the Glaser method considers only ste
19、ady-state conduction of heat and vapour diffusion, the transient models covered in this standard take account of heat and moisture storage, latent heat effects, and liquid and convective transport under realistic boundary and initial conditions. The application of such models has become widely used
20、in building practice in recent years, resulting in a significant improvement in the accuracy and reproducibility of hygrothermal simulation. The following examples of transient, one-dimensional heat and moisture phenomena in building components can be simulated by the models covered by this standard
21、: drying of initial construction moisture; moisture accumulation by interstitial condensation due to diffusion in winter; moisture penetration due to driving rain exposure; summer condensation due to migration of moisture from outside to inside; exterior surface condensation due to cooling by longwa
22、ve radiation exchange; moisture-related heat losses by transmission and moisture evaporation. The factors relevant to hygrothermal building component simulation are summarised below. The standard starts with the description of the physical model on which hygrothermal simulation tools are based. Then
23、 the necessary input parameters and their procurement are dealt with. A benchmark case with an analytical solution is given for the assessment of numerical simulation tools. The evaluation, interpretation and documentation of the output form the last part. Inputs Assembly, orientation and inclinatio
24、n of building components Hygrothermal material parameters and functions Boundary conditions, surface transfer for internal and external climate Initial condition, calculation period, numerical control parameters Outputs Temperature and heat flux distributions and temporal variations Water content, r
25、elative humidity and moisture flux distributions and temporal variations Post processing Energy use, economy heat transport by moisture-dependent thermal conduction; latent heat transfer by vapour diffusion; moisture storage by vapour sorption and capillary forces; moisture transport by vapour diffu
26、sion; moisture transport by liquid transport (surface diffusion and capillary flow). The equations described in this standard account for the following climatic variables: internal and external temperature; internal and external humidity; solar and longwave radiation; precipitation (normal and drivi
27、ng rain); wind speed and direction. The hygrothermal equations described in this standard shall not be applied in cases where: convection takes place through holes and cracks; two-dimensional effects play an important part (e.g. rising damp, conditions around thermal bridges, effect of gravitational
28、 forces); hydraulic, osmotic, electrophoretic forces are present; daily mean temperatures in the component exceed 50 C. EN 15026:2007 (E) 6 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited a
29、pplies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 12664, Thermal performance of building materials and products Determination of thermal resistance by means of guarded hot plate and heat flow meter methods Dry and moist products of m
30、edium and low thermal resistance EN 12667, Thermal performance of building materials and products Determination of thermal resistance by means of guarded hot plate and heat flow meter methods Products of high and medium thermal resistance EN 12939, Thermal performance of building materials and produ
31、cts Determination of thermal resistance by means of guarded hot plate and heat flow meter methods Thick products of high and medium thermal resistance EN ISO 7345, Thermal insulation Physical quantities and definitions (ISO 7345:1987) prEN ISO 9346:2005, Hygrothermal performance of buildings and bui
32、lding materials - Mass transfer - Physical quantities and definitions (ISO/DIS 9346:2005) prEN ISO 10456, Building materials and products - Hygrothermal properties -Tabulated design values and procedures for determining declared and design thermal values (ISO/DIS 10456:2005) EN ISO 12571, Hygrotherm
33、al performance of building materials and products Determination of hygroscopic sorption properties (ISO 12571:2000) EN ISO 12572, Hygrothermal performance of building materials and products Determination of water vapour transmission properties (ISO 12572:2001) prEN ISO 15927-3, Hygrothermal performa
34、nce of buildings - Calculation and presentation of climatic data - Part 3: Calculation of a driving rain index for vertical surfaces from hourly wind and rain data (ISO/DIS 15927-3:2006) 3 Terms, definitions, symbols and units 3.1 Terms and definitions For the purposes of this document, the terms an
35、d definitions given in prEN ISO 9346:2005 and EN ISO 7345 apply. Other terms used are defined in the relevant clauses of this standard. 3.2 Symbols and units Symbol Quantity Unit cmspecific heat capacity of dry material J/(kgK) cwspecific heat capacity of liquid water J/(kgK) Dwmoisture diffusivity
36、m2/s Esoltotal flux density of incident solar radiation W/m2EN 15026:2007 (E) 7 g density of moisture flow rate kg/(ms) gpdensity of moisture flow rate of available water from precipitation kg/(ms) gvdensity of water vapour flow rate kg/(ms) gwdensity of liquid water flow rate kg/(ms) gw,maxdensity
37、of water flow rate which can be absorbed at the surface of a material kg/(ms) h surface heat transfer coefficient W/(m2K) hcconvective heat transfer coefficient W/(m2K) hespecific latent enthalpy of evaporation or condensation J/kg hrradiative heat transfer coefficient W/(m2K) K liquid conductivity
38、s/m paambient atmospheric pressure Pa psucsuction pressure Pa pvpartial water vapour pressure Pa pv,apartial water vapour pressure in the air Pa pv,spartial water vapour pressure at a surface Pa pv,satsaturated water vapour pressure Pa pwwater pressure inside pores Pa q density of heat flow rate W/m
39、2qlatdensity of latent heat flow rate W/m2qsensdensity of sensible heat flow rate W/m2Rwliquid moisture flow resistance of interface m/s RH2Ogas constant of water vapour J/(kgK) sd,sequivalent vapour diffusion thickness of a surface layer m T thermodynamic temperature K Taair temperature of the surr
40、ounding environment K Teqequivalent temperature of the surrounding environment K EN 15026:2007 (E) 8 Trmean radiant temperature of the surrounding environment K Tsurfsurface temperature K t time s v wind speed m/s w moisture content kg/m3x distance m solsolar absorptance - 0vapour permeability of st
41、ill air kg/(msPa) pvapour permeability of material kg/(msPa) longwave emissivity of the external surface - thermal conductivity W/(mK) relative humidity - diffusion resistance factor - adensity of air kg/m mdensity of solid matrix kg/m wdensity of liquid water kg/m sStefan-Boltzmann constant W/(m2K4
42、) 4 Hygrothermal equations and material properties 4.1 Assumptions The hygrothermal equations specified in the following clauses contain the following assumptions: constant geometry, no swelling and shrinkage; no chemical reactions are occurring; latent heat of sorption is equal to latent heat of co
43、ndensation/evaporation; no change in material properties by damage or ageing; local equilibrium between liquid and vapour without hysteresis; moisture storage function is not dependent on temperature; temperature and barometric pressure gradients do not affect vapour diffusion. The development of th
44、e equations is based on the conservation of energy and moisture. The mathematical expression of the conservation laws are the balance equations. The conserved quantity changes in time, only if it is transported between neighbouring control volumes. EN 15026:2007 (E) 9 Heat conservation shall be expr
45、essed by ()()xqqtTwcc+=+latsenswmm (1) The increase of the moisture content of a control volume shall be determined by the net inflow of moisture. The moisture flow rate equals the sum of the vapour flow rate and the flow rate of liquid water. xgtw=(2) lvggg +=(3) The relative humidity shall be defi
46、ned by the following equation: ()Tppsatv,v= (4) The pressure acting on the water inside a building material due to the capillary forces is different from the pressure of the surrounding air. The difference is called suction. psuc= pa- pw(5) The suction of the pore water is related to the relative hu
47、midity of the surrounding air by the Kelvin equation: psuc= -w RH2OT ln (6) The relation between the state variables , pv, psuc, T and the moisture content of a building material is defined by the moisture storage function. The moisture storage function of a building material shall be expressed eith
48、er as the moisture content as a function of suction (suction curve), w(psuc), or as the moisture content as a function of the relative humidity (sorption curve), w(). 4.2 Transport of heat and moisture 4.2.1 Heat transport 4.2.1.1 Heat transport inside materials Heat transport shall be composed of s
49、ensible and latent components. Sensible heat transport shall be calculated with Fouriers law with a thermal conductivity which depends on moisture content. xTwq= )(sens (7) Latent heat transport shall be calculated by the following equation: velatghq = (8) 4.2.1.2 Heat transport across boundaries The heat flow from the surrounding environment into the construction consists of conv
