EN 674:2011
(Main)Glass in building - Determination of thermal transmittance (U value) - Guarded hot plate method
Glass in building - Determination of thermal transmittance (U value) - Guarded hot plate method
This European Standard specifies a measurement method to determine the thermal transmittance of glazing 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 glass and glass ceramics. Internal elements may be far infrared transparent.
The procedure specified in this European Standard determines the U value ) (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 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 for 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 for 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 other 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.
Glas im Bauwesen - Bestimmung des Wärmedurchgangskoeffizienten (U-Wert) - Verfahren mit dem Plattengerät
Diese Europäische Norm legt ein Messverfahren fest, das zur Bestimmung des Wärmedurchgangs-koeffizienten von hermetisch abgeschlossenen Verglasungen mit ebenen und parallelen Oberflächen dient. Strukturierte Oberflächen, z. B. Ornamentglas, dürfen als eben angesehen werden.
Diese Europäische Norm gilt für Mehrfachverglasungen mit äußeren Scheiben, die für Strahlung im fernen Infrarotbereich undurchlässig sind, was bei Produkten aus Natron-Kalk-Glas, Borosilicatglas und Glaskeramik der Fall ist. Die inneren Elemente dürfen jedoch für Strahlung im fernen Infrarotbereich durchlässig sein.
Das in dieser Europäischen Norm festgelegte Verfahren dient der Bestimmung des U Wertes ) (Wärmedurch-gangskoeffizient) im mittleren Bereich der Verglasung. Die Randwirkungen infolge der Wärmebrücke durch den Abstandshalter einer Isolierglaseinheit oder durch den Fensterrahmen sind nicht berücksichtigt. Die Wärmeübertragung durch Sonneneinstrahlung wurde ebenfalls nicht berücksichtigt.
Das in dieser Europäischen Norm festgelegte Verfahren sollte im Allgemeinen nur dann angewendet werden, wenn das in EN 673 ausführlich beschriebene Berechnungsverfahren ungeeignet ist.
Das Dokument für die Berechnung des Gesamt-U Werts von Fenstern, Türen und Abschlüssen (siehe [3]) enthält eine normative Verweisung auf den nach dieser Norm berechneten U Wert für die Verglasungselemente.
Es ist eine senkrechte Lage der Verglasung vorgeschrieben.
Die nach der vorliegenden Norm bestimmten U Werte werden sowohl für Produktvergleiche als auch zu weiteren Zwecken herangezogen, insbesondere für die Voraussage von:
- Wärmeverlusten durch Verglasungen;
- Erhöhungen der Wärmeleitung im Sommer;
- Tauwasserbildung auf Glasoberflächen;
- Auswirkungen der absorbierten Sonnenstrahlung auf die Bestimmung des Sonnenfaktors (siehe [1]).
Bei der Anwendung von nach dieser Norm bestimmten U Werten sollte auf [4], [5] oder weitere Europäische Normen, die sich mit der Berechnung von Wärmeverlusten befassen, Bezug genommen werden.
Die Bestimmung des Wärmedurchgangskoeffizienten erfolgt unter Bedingungen, die den durchschnittlichen Bedingungen für Verglasungen in der Praxis entsprechen.
Verre dans la construction - Détermination du coefficient de transmission thermique, U - Méthode de l'anneau de garde
La présente Norme européenne spécifie une méthode de mesure visant à déterminer le coefficient de transmission thermique, U, de vitrages dont les faces sont planes et parallèles. Pour les besoins de la présente norme, les surfaces structurées peuvent être considérées comme planes.
La présente Norme européenne spécifie une méthode de mesure utilisée pour déterminer le coefficient de transmission thermique de vitrages dont les faces sont planes et parallèles. Les faces structurées, par exemple le verre imprimé, peuvent être considérées comme planes.
La présente Norme européenne est applicable aux vitrages multiples dont les faces externes ne sont pas transparentes au rayonnement infrarouge lointain, ce qui est le cas des produits verriers de silicate sodo-calcique, du verre borosilicaté et du vitrocéramique. Les éléments internes peuvent être transparents au rayonnement infrarouge lointain.
Le mode opératoire défini dans la présente Norme européenne détermine l’expression de la valeur « U » ) (transmission thermique) dans la partie centrale du vitrage. Les effets de bord dus au pont thermique de l’intercalaire d’un vitrage isolant ou du châssis de fenêtre ne sont pas considérés. De plus, le transfert d’énergie dû au rayonnement solaire n’est pas pris en considération.
En général, il convient que le mode opératoire défini dans la présente Norme européenne soit pris en considération seulement lorsque la méthode de calcul détaillée dans l’EN 673 est inappropriée ou ne convient pas.
Le document relatif au calcul de la valeur U globale des fenêtres, portes et fermetures (voir [3]) donne une référence normative de la valeur U évaluée pour les composants verriers selon la présente norme.
La position verticale du vitrage est définie.
Les valeurs U évaluées selon la présente norme sont utilisées pour la comparaison de produits, mais peuvent également servir à d’autres buts, en particulier afin de prévoir :
- la perte de chaleur au travers des vitrages ;
- les gains de chaleur par conduction en été ;
- la condensation sur les faces des vitrages ;
- l’appréciation du rayonnement absorbé dans la détermination du facteur solaire (voir [1]).
Il convient de faire référence à [4], [5] ou à d’autres Normes européennes traitant du calcul des pertes de chaleur pour l’utilisation des valeurs U déterminées par la présente norme.
La détermination du coefficient de transfert thermique est effectuée dans des conditions d’utilisation moyenne des vitrages.
Steklo v gradbeništvu - Ugotavljanje toplotne prehodnosti (U-vrednost) - Metoda z vročo ploščo
Ta evropski standard opredeljuje merilno metodo za ugotavljanje toplotne prehodnosti zasteklitve s ploskimi in vzporednimi površinami. Strukturirane površine, npr. vzorčasto steklo, se lahko štejejo za ravne. Ta evropski standard velja za večkratno zasteklitev z zunanjimi šipami, ki pri skrajni infrardeči svetlobi niso prozorne, kot so mešanice natrijevega hidroksida in kalcijevega hidroksida, borosilikatno steklo in steklena keramika. Notranji elementi so lahko prozorni pri skrajni infrardeči svetlobi. S postopkom, ki ga opredeljuje ta evropski standard, se določa vrednost U (toplotna prehodnost) v osrednjem delu zasteklitve. Robni učinki zaradi toplotnega mostu med vmesnikom izolacijske steklene enote ali skozi okvir okna niso zajeti. Tudi prenos energije zaradi sončnega sevanja ni upoštevan. Postopek, opredeljen v tem evropskem standardu, se praviloma upošteva le, če je metoda izračuna, ki je podrobno opisana v EN 673, neprimerna ali neustrezna.
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
01-november-2011
1DGRPHãþD
SIST EN 674:1999
6WHNORYJUDGEHQLãWYX8JRWDYOMDQMHWRSORWQHSUHKRGQRVWL 8YUHGQRVW 0HWRGD]
YURþRSORãþR
Glass in building - Determination of thermal transmittance (U value) - Guarded hot plate
method
Glas im Bauwesen - Bestimmung des Wärmedurchgangskoeffizienten (U-Wert) -
Verfahren mit dem Plattengerät
Verre dans la construction - Détermination du coefficient de transmission thermique, U -
Méthode de l'anneau de garde
Ta slovenski standard je istoveten z: EN 674:2011
ICS:
81.040.20 Steklo v gradbeništvu Glass in building
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EUROPEAN STANDARD
EN 674
NORME EUROPÉENNE
EUROPÄISCHE NORM
June 2011
ICS 81.040.20 Supersedes EN 674:1997
English Version
Glass in building - Determination of thermal transmittance (U
value) - Guarded hot plate method
Verre dans la construction - Détermination du coefficient de Glas im Bauwesen - Bestimmung des
transmission thermique, U - Méthode de l'anneau de garde Wärmedurchgangskoeffizienten (U-Wert) - Verfahren mit
dem Plattengerät
This European Standard was approved by CEN on 29 April 2011.
CEN members are bound 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-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 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, Poland,
Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2011 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 674:2011: E
worldwide for CEN national Members.
Contents Page
Foreword .3
1 Scope .4
2 Normative references .4
3 Terms and definitions .5
4 Basic formula .5
5 Brief outline of the measuring procedure .5
6 Test apparatus .5
7 Dimensions of the specimens .6
8 Preparation of the specimens .6
9 Performance of the measurements.7
10 Evaluation of the results .7
10.1 Thermal resistance of the multiple glazing .7
10.2 Declared U Value.7
10.3 Design U value .8
11 Expression of the results .8
11.1 U values .8
11.2 Thermal resistance .8
11.3 Intermediate values .8
12 Test report .9
12.1 Information included in the test report .9
12.2 Identification of each glazing specimen .9
12.3 Cross section of the specimen .9
12.4 Results .9
Bibliography . 11
Foreword
This document (EN 674:2011) has been prepared by Technical Committee 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 withdrawn
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 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, Latvia,
Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.
1 Scope
This European Standard specifies a measurement method to determine the thermal transmittance of glazing
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 glass and glass ceramics.
Internal elements may be far infrared transparent.
1)
(thermal transmittance) in the
The procedure specified in this European Standard determines the U value
central area of glazing. The edge effects, due to the thermal bridge through the spacer of an insulating glass
unit or 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 for 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 for 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 other 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 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.
EN 12898, Glass in building Determination of the emissivity
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.
3 Terms and definitions
For the purposes of this standard, the following 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 on each side, and which is given in watts per square metre Kelvin [W/(m ·K)]
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 transfer coefficients according to the relation:
1 1 1
= R+ +
U h h
e i
(1)
where
[ ]
(m ⋅K)/W
R is the thermal resistance of the multiple glazing in square metres Kelvins per Watt ;
[(m ⋅K)/W]
h is the external surface heat transfer coefficient in Watts per square metre Kelvin ;
e
[(m ⋅K)/W]
h is the internal surface heat transfer coefficient in Watts per square metre Kelvin .
i
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 and 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 with 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 requirements 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
glazing.
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 assemblies 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 surface 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 thermocouples 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 grease 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 layers 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
acceptable 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 conductivity of the glass, i.e.
1 W/(m K), as the specimen thermal conductivity. If the r
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