1、September 2011 Translation by DIN-Sprachendienst.English price group 9No part of this translation may be reproduced without prior permission ofDIN Deutsches Institut fr Normung e. V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany,has the exclusive right of sale for German Standards (DIN-Normen).I
2、CS 81.040.20!$tGe“1813666www.din.deDDIN EN 674Glass in building Determination of thermal transmittance (U value) Guarded hot plate methodEnglish translation of DIN EN 674:2011-09Glas im Bauwesen Bestimmung des Wrmedurchgangskoeffizienten (U-Wert) Verfahren mit dem PlattengertEnglische bersetzung von
3、 DIN EN 674:2011-09Verre dans la construction Dtermination du coefficient de transmission thermique, U Mthode de lanneau de gardeTraduction anglaise de DIN EN 674:2011-09SupersedesDIN EN 674:1999-01www.beuth.deIn case of doubt, the German-language original shall be considered authoritative.Document
4、comprises pages08.1113DIN EN 674:2011-09 A comma is used as the decimal marker. National foreword This standard has been prepared by Technical Committee CEN/TC 129 “Glass in building” (Secretariat: NBN, Belgium). The responsible German body involved in its preparation was the Normenausschuss Bauwese
5、n (Building and Civil Engineering Standards Committee), Working Committee NA 005-09-91 AA Prfung von Beschichtungen auf Glas. Amendments This standard differs from DIN EN 674:1999-01 as follows: a) the internal and external heat transfer coefficients have been adjusted to reflect the modifications m
6、ade in EN 673; b) the standard has been editorially revised. Previous editions DIN 52619-2: 1985-02 DIN EN 674: 1999-01 2 EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 674 June 2011 ICS 81.040.20 Supersedes EN 674:1997English Version Glass in building - Determination of thermal transmittance
7、Verre dans la construction - Dtermination du coefficient de transmission thermique, U - Mthode de lanneau de gardeGlas im Bauwesen - Bestimmung des Wrmedurchgangskoeffizienten (U-Wert) - Verfahren mit dem Plattengert This European Standard was approved by CEN on 29 April 2011. CEN members are bound
8、to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-
9、CENELEC Management Centre or to any CEN member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has
10、 the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Po
11、land, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels 2011 CEN All rights of exploitation in any form and by
12、 any means reserved worldwide for CEN national Members. Ref. No. EN 674:2011: E(U value) - Guarded hot plate method EN 674:2011 (E) 2 Contents Page Foreword 31 Scope 42 Normative references 43 Terms and definitions .54 Basic formula .55 Brief outline of the measuring procedure .56 Test apparatus .57
13、 Dimensions of the specimens 68 Preparation of the specimens 69 Performance of the measurements710 Evaluation of the results .710.1 Thermal resistance of the multiple glazing .710.2 Declared U Value710.3 Design U value .811 Expression of the results 811.1 U values 811.2 Thermal resistance 811.3 Inte
14、rmediate values .812 Test report 912.1 Information included in the test report 912.2 Identification of each glazing specimen 912.3 Cross section of the specimen .912.4 Results 9Bibliography . 11DIN EN 674:2011-09 EN 674:2011 (E) 3 Foreword This document (EN 674:2011) has been prepared by Technical C
15、ommittee CEN/TC 129 “Glass in building”, the secretariat of which is held by NBN. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by December 2011, and conflicting national standards shall be withdra
16、wn at the latest by December 2011. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. This document supersedes EN 674:1997. According to
17、the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latv
18、ia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. DIN EN 674:2011-09 EN 674:2011 (E) 4 1 Scope This European Standard specifies a measurement method to determine the thermal transmittance of glazin
19、g with flat and parallel surfaces. Structured surfaces, e.g. patterned glass, can be considered to be flat. This European Standard applies to multiple glazing with outer panes which are not transparent to far infrared radiation, which is the case for soda lime silicate glass products, borosilicate g
20、lass and glass ceramics. Internal elements may be far infrared transparent. The procedure specified in this European Standard determines the U value1)(thermal transmittance) in the central area of glazing. The edge effects, due to the thermal bridge through the spacer of an insulating glass unit or
21、through the window frame are not included. Furthermore energy transfer due to solar radiation is not taken into account. The procedure specified in this European Standard should generally only be considered when the calculation method detailed in EN 673 is inappropriate or unsuitable. The document f
22、or the calculation of the overall U value of windows, doors and shutters (see 3) gives normative reference to the U value evaluated for the glazing components according to this standard. A vertical position of the glazing is specified. U values evaluated according to the present standard are used fo
23、r product comparison as well as for other purposes, in particular for predicting: heat loss through glazing; conduction heat gains in summer; condensation on glazing surfaces; the effects of the absorbed solar radiation in determining the solar factor (see 1). Reference should be made to 4, 5, or ot
24、her European Standards dealing with heat loss calculations for the application of glazing U values determined by this standard. The determination of the thermal transmittance is performed for conditions which correspond to the average situation for glazing in practice. 2 Normative references The fol
25、lowing 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. EN 12898, Glass in building Determination of the emissiv
26、ity ISO 8302:1991, Thermal insulation Determination of steady-state thermal resistance and related properties Guarded hot plate apparatus 1) In some countries the symbol k has been used hitherto. DIN EN 674:2011-09 EN 674:2011 (E) 5 3 Terms and definitions For the purposes of this standard, the foll
27、owing terms and definitions apply: 3.1 U value parameter of glazing: which characterizes the heat transfer through the central part of the glazing, i.e. without edge effects, which states the steady-state density of heat transfer rate per temperature difference between the environmental temperatures
28、 on each side, and which is given in watts per square metre Kelvin W/(m2K) 3.2 declared value U value obtained under standardized boundary conditions NOTE See 10.2. 4 Basic formula The U value depends on the thermal resistance of the multiple glazing and on the external and internal surface heat tra
29、nsfer coefficients according to the relation: iehhRU111+=(1) where R is the thermal resistance of the multiple glazing in square metres Kelvins per Watt WKm /)(2; he is the external surface heat transfer coefficient in Watts per square metre Kelvin WKm /)(2; hiis the internal surface heat transfer c
30、oefficient in Watts per square metre Kelvin WKm /)(2. According to this standard, the surface to surface thermal resistance is determined by measurements taken using the guarded hot plate method. Thereupon the declared value is determined according to Equation (1) with the values for the internal an
31、d external heat transfer coefficients specified in 10.2. 5 Brief outline of the measuring procedure The surface to surface thermal resistance of the multiple glazing is determined by means of the guarded hot plate method laid down in ISO 8302. The recommendations of that standard shall be complied w
32、ith except for variations contained in this standard and for variations resulting from the special structure of the glazing. Within the present context further requirements are necessary, viz. the size of the test specimens and the performance of the measurements are laid down to meet special requir
33、ements for measuring multiple glazing (see Clause 6 to Clause 12). 6 Test apparatus For the measurement of the thermal resistance of the specimen, the two specimen apparatus is used. Figure 1 gives a general outline of this apparatus including special requirements for the measurement of multiple gla
34、zing. DIN EN 674:2011-09 EN 674:2011 (E) 6 A square flat plate assembly consisting of a heater and metal surface plates and called the heating unit is sandwiched between two nearly identical specimens. The thermal flux is transferred through the specimens to separate square isothermal flat assemblie
35、s called the cooling units. The heating unit consists of a separate central metering section, where the unidirectional constant heat flux can be established, surrounded by a guard section separated by a narrow gap. The metering section has dimensions of 500 mm x 500 mm. The cooling units have surfac
36、e dimensions as large as those of the heating unit, including the guard heater. To ensure sufficient contact between the specimens and the adjacent surface plates, rubber sponge sheets in the quality of natural rubber with a thickness of about 3 mm shall be used. A minimum of three equally spaced th
37、ermocouples shall be positioned on the specimen diagonal on each side to determine the average surface temperatures. Such thermocouples shall have a thickness not exceeding 0,2 mm; the junctions shall be flattened so as not to exceed 0,2 mm and a contact material (e.g. zinc oxide loaded silicon grea
38、se or metal tape) shall be used to insure a good thermal contact between the junction and the specimen. The specimens shall be of such a size as to completely cover the heating unit surface. Additional edge insulation and/or auxiliary guard sections are required as stated in ISO 8302. The glass laye
39、rs of multiple glazing in contact with the apparatus make critical the correct detection of imbalance across the gap due to the high thermal conductivity of the glass. The installation of imbalance sensors as indicated in Figure 4b) of ISO 8302:1991 is most probably the only way of detecting with ac
40、ceptable accuracy the actual imbalance through the gap when testing multiple glazing, see 2.1.1.3 to 2.1.1.5 of ISO 8302:1991. When a guarded hot plate is intended for tests on multiple glazing, the imbalance error shall be evaluated according to 2.2.1 of ISO 8302:1991, using the thermal conductivit
41、y of the glass, i.e. 1 W/(m K), as the specimen thermal conductivity. If the resulting calculated imbalance error is larger than 1 % (instead of the 0,5 % required by 2.1.4.1.1 of ISO 8302:1991), then the imbalance error shall be assessed using the experimental procedure of 2.4.4 of ISO 8302:1991. I
42、f the 1 % limit is still exceeded, the gap design and the imbalance detection system shall be reviewed before attempting any test on multiple glazing. 7 Dimensions of the specimens The specimens shall be square and have dimensions of preferably 800 mm x 800 mm with a maximum spread ranging from 750
43、mm x 750 mm to 850 mm x 850 mm. The two specimens needed for the measurement shall be as identical as possible. The difference in thickness between the two specimens measured at the edges shall not be more than 2 %. The surfaces of the specimens shall be flat and parallel. Specimen sizes down to 450
44、 mm x 450 mm may be used if it can be shown that no convection occurs in the gas space and that the errors occurring are not greater than those allowed for the 800 mm x 800 mm arrangement. 8 Preparation of the specimens The sum of the bowing or dishing of the outer panes in the central area of each
45、specimen shall not exceed 0,5 mm. The control of bowing or dishing effects is performed by cooling down the specimens to 10 C until isothermal equilibrium is reached and by measuring immediately before the specimens are positioned in the test apparatus for the measurement. DIN EN 674:2011-09 EN 674:
46、2011 (E) 7 In the case of excessive bowing, a correction of the thickness of the specimens in the central area may be performed by a corresponding pressure change. In the case of excessive dishing such a correction for gas fillings except air is only allowed if the needed correction (by introducing
47、a small volume of air) does not exceed 0,5 mm. 9 Performance of the measurements The measurements shall be taken with the specimens in a vertical position. The measurements shall be performed at a mean temperature of each specimen of (10 0,5) C. The mean temperature difference between the hot and th
48、e cold surface of the specimens shall be (15 0,5) K. 10 Evaluation of the results 10.1 Thermal resistance of the multiple glazing The thermal resistance R is calculated according to the equation: =)TA(TR212m2K/W (2) where is the average power supplied to the central section of the heating unit in wa
49、tts (W); T1is the average hot side temperature of the specimens in Kelvins (K); T2is the average cold side temperature of the specimens in Kelvins (K); A is the metering area in square metres (m2). 10.2 Declared U Value The declared U value is calculated according to Equation (1). For multiple glazing without a coating having an emissivity lower than 0,837 on the outer surfaces, the following standardized values for the surfa
