# ISO 10211-2007

Reference number ISO 102112007E ISO 2007INTERNATIONAL STANDARD ISO 10211 First edition 2007-12-15 Thermal bridges in building construction Heat flows and surface temperatures Detailed calculations Ponts thermiques dans les btiments Flux thermiques et tempratures superficielles Calculs dtaills Licensed to /PETER WARM ISO Store order 875662/Downloaded2008-01-11 Single user licence only, copying and networking prohibitedISO 102112007E PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing policy, this file may be printed or viewed but shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer pering the editing. In downloading this file, parties accept therein the responsibility of not infringing Adobes licensing policy. The ISO Central Secretariat accepts no liability in this area. Adobe is a trademark of Adobe Systems Incorporated. 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ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. 41 22 749 01 11 Fax 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2007 All rights reservedLicensed to /PETER WARM ISO Store order 875662/Downloaded2008-01-11 Single user licence only, copying and networking prohibitedISO 102112007E ISO 2007 All rights reserved iii Contents Page Foreword. v Introduction . vi 1 Scope 1 2 Normative references 1 3 Terms, definitions, symbols, units and subscripts2 3.1 Terms and definitions .2 3.2 Symbols and units.6 3.3 Subscripts 7 4 Principles7 5 Modelling of the construction 7 5.1 Dimension systems .7 5.2 Rules for modelling .7 5.3 Conditions for simplifying the geometrical model.13 6 data17 6.1 General17 6.2 Thermal conductivities of materials 18 6.3 Surface resistances.18 6.4 Boundary temperatures 18 6.5 Thermal conductivity of quasi-homogeneous layers 18 6.6 Equivalent thermal conductivity of air cavities 18 6.7 Determining the temperature in an adjacent unheated room .19 7 Calculation 19 7.1 Solution technique.19 7.2 Calculation rules19 8 Determination of thermal coupling coefficients and heat flow rate from 3-D calculations .20 8.1 Two boundary temperatures, unpartitioned model20 8.2 Two boundary temperatures, partitioned model20 8.3 More than two boundary temperatures .21 9 Calculations using linear and point thermal transmittances from 3-D calculations 21 9.1 Calculation of thermal coupling coefficient21 9.2 Calculation of linear and point thermal transmittances 22 10 Determination of thermal coupling coefficient, heat flow rate and linear thermal transmittance from 2-D calculations23 10.1 Two boundary temperatures 23 10.2 More than two boundary temperatures .23 10.3 Determination of the linear thermal transmittance 23 10.4 Determination of the linear thermal transmittance for wall/floor junctions.24 10.5 Determination of the external periodic heat transfer coefficient for ground floors .25 11 Determination of the temperature at the internal surface .26 11.1 Determination of the temperature at the internal surface from 3-D calculations .26 11.2 Determination of the temperature at the internal surface from 2-D calculations .27 12 and output data 28 12.1 data28 12.2 Output data.28 Annex A normative Validation of calculation s 30 Licensed to /PETER WARM ISO Store order 875662/Downloaded2008-01-11 Single user licence only, copying and networking prohibitedISO 102112007E iv ISO 2007 All rights reservedAnnex B inative Examples of the determination of the linear and point thermal transmittances. 37 Annex C inative Determination of values of thermal coupling coefficient and temperature weighting factor for more than two boundary temperatures . 40 Bibliography . 45 Licensed to /PETER WARM ISO Store order 875662/Downloaded2008-01-11 Single user licence only, copying and networking prohibitedISO 102112007E ISO 2007 All rights reserved v Foreword ISO the International Organization for Standardization is a worldwide federation of national standards bodies ISO member bodies. The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission IEC on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 10211 was prepared by Technical Committee ISO/TC 163, Thermal perance and energy use in the built environment, Subcommittee SC 2, Calculation s. This first edition of ISO 10211 cancels and replaces ISO 10211-11995 and ISO 10211-22001, which have been technically revised. The principal changes are as follows this first edition of ISO 10211 merges the title and general contents of ISO 10211-11995 and ISO 10211-22001 into a single document; Clause 3 indicates that ISO 10211 now uses only temperature factor, and not temperature difference ratio; 5.2.2 specifies that cut-off planes are to be located at the larger of 1 m and three times the thickness of the flanking element; 5.2.4 contains a revised version of Table 1 to correct error for three-dimensional calculations and to clarify intentions; 5.2.7 specifies that acceptable criterion is either on heat flow or on surface temperature; the heat flow criterion has been changed from 2 to 1 ; 6.3 specifies that surface resistance values are to be obtained from ISO 6946 for heat flow calculations and from ISO 13788 for condensation calculations; the contents of Anns E and G of ISO 10211-11995 have been deleted in favour of references to ISO 13788; 6.6 specifies that data for air cavities is obtained from ISO 6946, EN 673 or ISO 10077-2; the contents of Annex B of ISO 10211-11995 have been deleted in favour of these references; 10.4 contains text erly in ISO 13370, revised to specify that linear thermal transmittance values for wall/floor junctions are the difference between the numerical result and the result from using ISO 13370 a more consistent definition; Annex A contains corrections to results for case 3; the conity criterion for case 3 has been changed from 2 of heat flow to 1 ; a new case 4 has been added; Annex C contains a corrected procedure; all remaining anns from ISO 10211-11995 and ISO 10211-22001 have been deleted. Licensed to /PETER WARM ISO Store order 875662/Downloaded2008-01-11 Single user licence only, copying and networking prohibitedISO 102112007E vi ISO 2007 All rights reservedIntroduction Thermal bridges, which in general occur at any junction between building components or where the building structure changes composition, have two consequences compared with those of the unbridged structure a a change in heat flow rate, and b a change in internal surface temperature. Although similar calculation procedures are used, the procedures are not identical for the calculation of heat flows and of surface temperatures. A thermal bridge usually gives rise to three-dimensional or two-dimensional heat flows, which can be precisely determined using detailed numerical calculation s as described in this International Standard. In many applications, numerical calculations based on a two-dimensional representation of the heat flows provide results of adequate accuracy, especially when the constructional element is uni in one direction. A discussion of other s for assessing the effect of thermal bridges is provided in ISO 14683. ISO 10211 was originally published in two parts, dealing with three-dimensional and two-dimensional calculations separately. Licensed to /PETER WARM ISO Store order 875662/Downloaded2008-01-11 Single user licence only, copying and networking prohibitedINTERNATIONAL STANDARD ISO 102112007E ISO 2007 All rights reserved 1 Thermal bridges in building construction Heat flows and surface temperatures Detailed calculations 1 Scope This International Standard sets out the specifications for a three-dimensional and a two-dimensional geometrical model of a thermal bridge for the numerical calculation of heat flows, in order to assess the overall heat loss from a building or part of it; minimum surface temperatures, in order to assess the risk of surface condensation. These specifications include the geometrical boundaries and subdivisions of the model, the thermal boundary conditions, and the thermal values and relationships to be used. This International Standard is based upon the following assumptions all physical properties are independent of temperature; there are no heat sources within the building element. This International Standard can also be used for the derivation of linear and point thermal transmittances and of surface temperature factors. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document including any amendments applies. ISO 6946, Building components and building elements Thermal resistance and thermal transmittance Calculation ISO 7345, Thermal insulation Physical quantities and definitions ISO 133702007, Thermal perance of buildings Heat transfer via the ground Calculation s ISO 13788, Hygrothermal perance of building components and building elements Internal surface temperature to avoid critical surface humidity and interstitial condensation Calculation s Licensed to /PETER WARM ISO Store order 875662/Downloaded2008-01-11 Single user licence only, copying and networking prohibitedISO 102112007E 2 ISO 2007 All rights reserved3 Terms, definitions, symbols, units and subscripts 3.1 Terms and definitions For the purposes of this document, the terms and definitions given in ISO 7345 and the following apply. 3.1.1 thermal bridge part of the building envelope where the otherwise uni thermal resistance is significantly changed by full or partial penetration of the building envelope by materials with a different thermal conductivity, and/or a change in thickness of the fabric, and/or a difference between internal and external areas, such as occur at wall/floor/ceiling junctions 3.1.2 linear thermal bridge thermal bridge with a uni cross-section along one of the three orthogonal axes 3.1.3 point thermal bridge localized thermal bridge whose influence can be represented by a point thermal transmittance 3.1.4 three-dimensional geometrical model 3-D geometrical model geometrical model, deduced from building plans, such that for each of the orthogonal axes the cross-section perpendicular to that axis changes within the boundary of the model See Figure 1. 3.1.5 three-dimensional flanking element 3-D flanking element part of a 3-D geometrical model which, when considered in isolation, can be represented by a 2-D geometrical model See Figures 1 and 2. 3.1.6 three-dimensional central element 3-D central element part of a 3-D geometrical model which is not a 3-D flanking element See Figure 1. NOTE A central element is represented by a 3-D geometrical model. 3.1.7 two-dimensional geometrical model 2-D geometrical model geometrical model, deduced from building plans, such that for one of the orthogonal axes the cross-section perpendicular to that axis does not change within the boundaries of the model See Figure 2. NOTE A 2-D geometrical model is used for two-dimensional calculations. 3.1.8 two-dimensional flanking element 2-D flanking element part of a 2-D geometrical model which, when considered in isolation, consists of plane, parallel material layers Licensed to /PETER WARM ISO Store order 875662/Downloaded2008-01-11 Single user licence only, copying and networking prohibitedISO 102112007E ISO 2007 All rights reserved 3 3.1.9 two-dimensional central element 2-D central element part of a 2-D geometrical model which is not a 2-D flanking element 3.1.10 construction planes planes in the 3-D or 2-D geometrical model which separate different materials, and/or the geometrical model from the remainder of the construction, and/or the flanking elements from the central element See Figure 3. 3.1.11 cut-off planes construction planes that are boundaries to the 3-D or 2-D geometrical model by separating the model from the remainder of the construction See Figure 3. 3.1.12 auxiliary planes planes which, in addition to the construction planes, divide the geometrical model into a number of cells 3.1.13 quasi-homogeneous layer layer which consists of two or more materials with different thermal conductivities, but which can be considered as a homogeneous layer with an effective thermal conductivity See Figure 4. 3.1.14 temperature factor at the internal surface difference between internal surface temperature and external temperature, divided by the difference between internal temperature and external temperature, calculated with a surface resistance R siat the internal surface 3.1.15 temperature weighting factor weighting factor which states the respective influence of the temperatures of the different thermal environments upon the surface temperature at the point under consideration 3.1.16 external boundary temperature external air temperature, assuming that the air temperature and the radiant temperature seen by the surface are equal 3.1.17 i