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BRITISH STANDARD BS EN ISO
10077-1:2000
Corrected and reprinted
December 2001
The European Standard EN ISO 10077-1:2000 has the status of a BritishStandard
ICS 91.060.50; 91.120.10
NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW
Thermal performance of windows, doors and
shutters Ð Calculation
of thermal
transmittance ÐPart 1: Simplified method
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This British Standard, havingbeen prepared under thedirection of the Sector Committee for Building and CivilEngineering, was published under the authority of the StandardsCommittee and comes into effecton 15 September 2000
© BSI 10 December 2001
ISBN 0 580 32641 1
BS EN ISO 10077-1:2000
Amendments issued since publication
Amd. No. Date Comments
National foreword
This British Standard is the official English language version of EN ISO 10077-1:2000.It is identical with EN ISO 10077-1:2000.
The UK participation in its preparation was entrusted by Technical Committee
B/540, Energy performance of materials, components and buildings, toSubcommittee B/540/1, European Standards for thermal insulation, which has theresponsibility to:
Ð aid enquirers to understand the text;
Ð present to the responsible international/European committee any enquirieson the interpretation, or proposals for change, and keep the UK interestsinformed;
Ð monitor related international and European developments and promulgatethem in the UK.
A list of organizations represented on this subcommittee can be obtained on requestto its secretary.
Cross-references
Attention is drawn to the fact that CEN and CENELEC Standards normally includean annex which lists normative references to international publications with their corresponding European publications. The British Standards which implement theseinternational or European publications may be found in the BSI StandardsCatalogue under the section entitled ªInternational Standards CorrespondenceIndexº, or by using the ªFindº facility of the BSI Standards Electronic Catalogue.
A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application.
Compliance with a British Standard does not of itself confer immunity
from legal obligations.
Summary of pages
This document comprises a front cover, an inside front cover, the EN ISO title page, pages 2 to 31 and a back cover.
The BSI copyright notice displayed in this document indicates when this documentwas updated.
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EUROPEAN STANDARD
NORME EUROPÉENNE
EUROPÄISCHE NORM
EN ISO 10077-1
July 2000
ICS 91.060.50; 91.120.10
English version
Thermal performance of windows, doors and shutters -Calculation of thermal transmittance - Part 1: Simplified method
(ISO 10077-1:2000)
Performance thermique des fenêtres, portes et fermetures -Calcul du coefficient de transmission thermique - Partie 1:
Méthode simplifiée (ISO 10077-1:2000)
Wärmetechnisches Verhalten von Fenstern, Türen undAbschlüssen - Berechnung des
Wärmedurchgangskoeffizienten - Teil 1: VereinfachtesVerfahren (ISO 10077-1:2000)
This European Standard was approved by CEN on 21 July 1999.
CEN members are bound to comply with the CEN/CENELEC 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 Central Secretariat or to any CEN 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 Central Secretariat has the same status as the officialversions.
CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece,Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMIT É E UROPÉ E N DE NORMAL ISAT ION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Central Secretariat: rue de Stassart, 36 B-1050 Brussels
© 2000 CEN All rights of exploitation in any form and by any means reservedworldwide for CEN national Members.
Ref. No. EN ISO 10077-1:2000 E
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Page 2EN ISO 10077-1:2000
Contents
Page
Foreword 3
Introduction 3
1 Scope 4
2 Normative references 5
3 Definitions, symbols and units 6
4 Geometrical characteristics 7
5 Calculation of thermal transmittance 9
6 Input data 15
7 Report 15
Annex A (normative) Internal and external surface thermal resistances 17
Annex B (informative) Thermal conductivity of glass 17
Annex C (informative) Thermal resistance of air spaces between glazing and thermaltransmittance of coupled or double glazing 18
Annex D (informative) Thermal transmittance of frames 20
Annex E (informative) Linear thermal transmittance of frame/glazing junction 25
Annex F (informative) Thermal transmittance of windows 26
Annex G (informative) Additional thermal resistance for windows with closed shutters 28
Annex H (informative) Permeability of shutters 29
Annex ZA (informative) A-deviations 31
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Foreword
The text of EN ISO 10077-1:2000 has been prepared by Technical Committee CEN/TC 89"Thermal performance of buildings and building components", the secretariat of which is heldby SIS , in collaboration with Technical Committee ISO/TC 163 "Thermal insulation".
This European Standard shall be given the status of a national standard, either by publicationof an identical text or by endorsement, at the latest by January 2001, and conflicting nationalstandards shall be withdrawn at the latest by January 2001.
For relationship with EU Directive(s), see informative Annex ZA, which is an integral part ofthis standard.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of
the following countries are bound to implement this European Standard: Austria, Belgium,Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy,Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the UnitedKingdom.
This standard is one of a series of standards on calculation methods for the design and
evaluation of the thermal performance of buildings and building components.
It contains two parts. Part 1 deals with the simplified calculation of the thermal transmittance
of windows and doors with or without shutters. Part 2 covers the numerical calculation (two-
dimensional) of the thermal transmittance of frame profiles.
Introduction
The method described in this standard is used to evaluate the thermal transmittance of
windows and doors, or as part of the determination of the energy use of a building.
An alternative to this calculation method is testing according to EN ISO 12567 “Thermal
performance of windows and doors – Determination of thermal transmittance by hot box
methods”.
In some countries the calculation of the thermal transmittance of windows forms part of their
national regulations. Information about national deviations from this standard due to
regulations are given in annex ZA.
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1 Scope
This standard specifies methods for the calculation of the thermal transmittance of windows
and doors consisting of glazed or opaque panels fitted in a frame, with and without shutters.
It allows for:
- different types of glazing (glass or plastics; single or multiple glazing; with or without
low emissivity coatings; with spaces filled with air or other gases);
- various types of frames (wood; plastic; metallic with and without thermal barrier;
metallic with pinpoint metallic connections or any combination of materials);
- where appropriate, the additional thermal resistance introduced by different types of
shutters, depending on their air permeability.
Curtain walls and other structural glazings, which are not fitted in a frame, are excluded fromthis standard. Roof windows are also excluded because of their complex geometrical frame
sections.
Default values for glazings, frames and shutters are given in the informative annexes. Thermal
bridge effects at the rebate or joint between the window or door frame and the rest of the
building envelope are excluded from the calculation.
The calculation does not include:
– effects of solar radiation; – heat transfer caused by air leakage;
– calculation of condensation;
– ventilation of air spaces in double and coupled windows.
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2 Normative references
This standard incorporates by dated or undated reference, provisions from other publications.
These normative references are cited at the appropriate places in the text and the publicationsare listed hereafter. For dated references, subsequent amendments to or revisions of any of
these publications apply to this standard only when incorporated in it by amendment or
revision. For undated references the latest edition of the publications referred to applies.
EN 673 Glass in building – Determination of thermal transmittance (U value) –
Calculation method
EN 674 Glass in building – Determination of thermal transmittance (U value)
Guarded hot plate method
EN 675 Glass in building – Determination of thermal transmittance (U value) –
Heat flow meter methodprEN 1098 Measuring method for the determination of the thermal transmittance of
multiple glazing (U value) – Calibrated and guarded hot box method
prEN 1279-1 Glass in building - Insulating glass units - Part 1: Generalities and
dimensional tolerances
prEN 1279-3 Glass in building - Insulating glass units - Part 3: Initial type testing on
gas-filled insulating glass units; gas leakage rate
prEN 12412-2 Windows, doors and shutters - Determination of thermal transmittance
by hot box method – Part 2: Frames
EN 12524 Building materials and products – Hygrothermal properties – Tabulated
design valuesEN ISO 6946 Building components and building elements – Thermal resistance and
thermal transmittance – Calculation method (ISO 6946)
EN ISO 7345 Thermal insulation – Physical quantities and definitions (ISO 7345)
prEN ISO 10077-2 Thermal performance of windows, doors and shutters - Calculation of
thermal transmittance - Part 2: Numerical method for frames
(ISO/DIS 10077-2)
EN ISO 10211-2 Thermal bridges in building construction - Calculation of heat flows and
surface temperatures - Part 2: Linear thermal bridges (ISO 10211-2)
ISO 8302 Thermal insulation – Determination of steady-state thermal resistance
and related properties – Guarded hot plate apparatus
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3 Definitions, symbols and units
3.1 Definitions
For the purposes of this standard, the definitions given in EN 673 and EN ISO 7345 apply.
In clause 4 of this standard, descriptions are given of a number of geometrical characteristics
of glazing and frame.
3.2 Symbols
Symbol Quantity Unit
A area m2
R thermal resistance m2·K/W
T temperature KU thermal transmittance W/(m2·K)
b width m
d distance / thickness m
l length m
q density of heat flow rate W/m2
linear thermal transmittance W/(m·K)
thermal conductivity W/(m·K)
3.3 Subscripts
Figure 1 - Internal and external developed area
D door
W window
WS window with closed shutter j summation index
d developed p panel (opaque)
e external s space (air or gas space)
f frame se external surface
g glazing sh shutter
i internal si internal surface
sa sash
Ad,e
frame
Ad,i
external
internal
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4 Geometrical characteristics
4.1 Glazed area, opaque panel area
The glazed area Ag or the opaque panel area Ap of a window or door is the smaller of the
visible areas seen from both sides, see figure 2. Any overlapping of gaskets is ignored.
4.2 Total visible perimeter of the glazing
The total perimeter of the glazing lg (or the opaque panel lp) is the sum of the visible perimeter
of the glass panes (or opaque panels) in the window or door. If the perimeters are different on
either side of the pane or panel then the larger of the two shall be used, see figure 2.
l gglass
l g
Ag
Figure 2 - Illustration of glazed area and perimeter
4.3 Frame areas
For the definition of the areas see also figure 3.
Af,i Internal projected frame area
The internal projected frame area is the area of the projection of the internal frame on
a plane parallel to the glazing panel.
Af,e External projected frame area
The external projected frame area is the area of the projection of the external frame
on a plane parallel to the glazing panel.
Af Frame area
The frame area is the larger of the two projected areas seen from both sides.
Ad,i Internal developed frame area
The internal developed frame area is the area of the frame in contact with the internal
air (see figure 1).
Ad,e External developed frame area
The external developed frame area is the area of the frame in contact with the
external air (see figure 1).
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4.4 Window area
The window area Aw is the sum of the frame area Af and the glazing area Ag (or the
panel area Ap).
A5 A6
Af,e
Aw
external
A7
A8
A4
A3A1
Af,i = Af Ag
internal
A2
frame(fixed)
sash(movable)
NOTE Af = max (Af,i ; Af,e)Aw = Af + AgAd,i = A1 + A2 + A3 + A4Ad,e = A5 + A6 + A7 + A8
Figure 3 - Illustration of the various areas
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5 Calculation of thermal transmittance
5.1 Windows
5.1.1 Single windows
frame(fixed)
glazing (singleor multiple)
sash(movable)
Figure 4 - Illustration of single window
The thermal transmittance of a single window U w shall be calculated using equation (1):
U A U A U l
A AW
g g f f g g
g f
(1)
where
U g is the thermal transmittance of the glazing;
U f is the thermal transmittance of the frame;
g is the linear thermal transmittance due to the combined thermal effects of glazing,
spacer and frame;
and the other symbols are defined in clause 4.
In the case of single glazing the last term of the numerator in equation (1) shall be taken as
zero (no spacer effect) because any correction is negligible.
When opaque panels are used instead of some of the glazing, U w is calculated as follows:
U A U A U A U l l
A A AW
g g p p f f g g p p
g p f
(2)
where
U p is the thermal transmittance of the opaque panel(s);
p is the linear thermal transmittance for the opaque panel(s).
If the opaque panel is thermally bridged at the edge by a less insulating spacer, the effect of
the bridging shall be taken into account in the same way as for glazing; otherwise p = 0.
NOTE Typical values of the linear thermal transmittance are given in annex E.
prEN ISO 10077-2 gives a method for calculating linear thermal transmittance.
prEN 12412-2 gives a method for measuring the linear thermal transmittance.
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5.1.2 Double windows
The thermal transmittance U W of a system consisting of two separate windows shall be
calculated by the following equation:
U U R R R U
W
W si s se W
1
1 11 2 / / (3)
where
U W1, U W2 are the thermal transmittances of the external and internal window; respectively,
calculated according to equation (1);
Rsi is the internal surface resistance of the external window when used alone;
Rse is the external surface resistance of the internal window when used alone;
Rs is the thermal resistance of the space between the glazing in the two windows.
Typical values of Rsi and Rse are given in normative annex A and of Rs in the informative annex
C.
NOTE If the gap exceeds 3 mm and measures have not been taken toprevent excessive air exchange with external air, the method does not apply.
glazing (singleor multiple)
external
internal
R se
R s
1 /U w1
R si
1 /U w
1 /U w2
frame(fixed)
sash(movable)
3 mm
3 mm
Figure 5 - Illustration of double window
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5.1.3 Coupled windows
The thermal transmittance U w of a systemconsisting of one frame and two separate
sashes shall be calculated using equation (1).To determine the thermal transmittance U g ofthe combined glazing equation (4) shall beused:
U U R R R U
g
1
1 1g1 si s se g2 / / (4)
where
U g1 , U g2 are the thermal transmittances of the external and internal glazing; respectively,calculated according to equations (5) and (6);
Rsi is the internal surface resistance of the external glazing when used alone;
Rse is the external surface resistance of the internal glazing when used alone;
Rs is the thermal resistance of the space between the internal and external glazing.
Typical values of Rsi and Rse are given in normative annex A and of Rs in the informative annex
C.
NOTE If the gap exceeds 3 mm and measures have not been taken toprevent excessive air exchange with external air, the method does not apply.
5.2 Glazing
5.2.1 Single glazing
The thermal transmittance of the single and laminated glazing, U g, shall be calculated with the
following equation:
sise
1
Rd
R
U
j j
j
g
(5)
where
Rse is the external surface resistance;
j is the thermal conductivity of glass or material layer j;
d j is the thickness of the glass pane or material layer j;
Rsi is the internal surface resistance.
external
internal
3 mm
glazing (single
or multiple)
Figure 6 - llustration of coupled windows
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5.2.2 Multiple glazing
The thermal transmittance of multiple glazing U g can be calculated according to EN 673 or by
means of the following equation:
si,sse
g
1
R Rd
R
U
j
j
j j
j
(6)
where
Rse is the external surface resistance;
j is the thermal conductivity of glass or material layer j;
d j is the thickness of the glass pane or material layers j;
Rsi is the internal surface resistance;
Rs, j is the thermal resistance of air space j.
NOTE Typical values of Rs are given in informative annex C.
5.3 Windows with closed shutters
A shutter on the outside of a window introduces an additional thermal resistance, resulting
from both the air layer enclosed between the shutter and the window, and the shutter itself
(see figure 7). The thermal transmittance of a window with closed shutters, U ws, is given by:
RU U
WWS
/ 1
1 (7)
where
U w is the thermal transmittance of the window;
R is the additional thermal resistance due to the air layer enclosed between the shutter
and the window and the closed shutter itself (see figure 7).
external internal
shutter
R
Rsh
EMBED
Figure 7 - Window with external shutter
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The additional thermal resistance for five categories of shutter air permeability is given in the
following expressions:
– shutters with very high air permeability:
R = 0,08 m2
K/W (8)
– shutters with high air permeability:
R = 0,25 Rsh + 0,09 m2
K/W (9)
– shutters with an average air permeability (for example solid wing shutters, wooden
venetian shutters with solid overlapping slats, roller shutters made of wood, plastic or
metal, with connecting slats):
R = 0,55 Rsh + 0,11 m2
K/W (10)
– shutters with low air permeability:
R = 0,80 Rsh + 0,14 m2 K/W (11)
– tight shutters:
R = 0,95 Rsh + 0,17 m2
K/W (12)
where Rsh is the thermal resistance of the shutter itself.
The above equations are valid for Rsh < 0,3 m2
K/W. If no measured or calculated values for Rshare available, the typical values given in annexes G and H can be used. For external orinternal blinds use equations (8) to (12) with Rsh = 0.
NOTE 1 Annex H gives further information about the permeability of
shutters.
NOTE 2 The expression R for tight shutters is the best current
estimate, and future developments may lead to other values.
5.4 Doors
frame(fixed)
glazing (single,or multiple)
sash(movable)
Figure 8 - Illustration of door with glazing
The thermal transmittance U D of a doorset, which is of similar design to a window, is obtained
using equation (13).
U A U A U l A A
Dg g f f g g
g f
(13)
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where Af , Ag and lg are defined in clause 4;
U g is the thermal transmittance of the glazing;
U f is the thermal transmittance of the frame;
g is the linear thermal transmittance due to the combined thermal effects oglazing
spacer and frame;
In the case of single glazing the last term of the numerator in equation (13) shall be taken as
zero (no spacer effect) because any correction is negligible.
frame(fixed)
opaque
panel
sash(movable)
Figure 9 - Schematic illustration of door with opaque panel
If the door consists of frame, glazing and opaque panels, then the following equation shall be
used:
U A U A U AU l l
A A AD
g g p p f f g g p p
g p f
(14)
where
Ap and lp are defined in clause 4;U p is the thermal transmittance of the opaque panel(s);
p is the linear thermal transmittance for opaque panels.
If the opaque panel is thermally bridged at the edge by a less insulating spacer, the effect of
the bridging shall be taken into account in the same way as for glazing.
NOTE 1 Annex D gives typical values of U f for different types of frame.
prEN ISO 10077-2 gives a method for calculating the linear thermal transmittance.
NOTE 2 Typical values of are given in annex E.
The thermal transmittance of door leaves without a frame and without inhomogeneities
(having different layers only perpendicular to the heat flow direction) can be measured in the
guarded hot plate apparatus, in accordance with ISO 8302.
If the doorset does not have a design similar to a window system then the thermal
transmittance of the door leaves can be calculated in accordance with EN ISO 6946 provided
that the ratio of the thermal conductivities of any two different materials in the door does not
exceed 1:5 (screws, nails, and so on are excluded); this method includes the calculation of the
maximum relative error which should be less than 10 %.
If the maximum relative error is higher than 10 % or the ratio of the thermal conductivities of
the different materials is greater than 1:5 a numerical calculation in accordance with
prEN ISO 10077-2 and/or EN ISO 10211-2 should be carried out.
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6 Input data
The thermal transmittance of the frame, U f , is to be determined with the glazing replaced with
a material of thermal conductivity not exceeding 0,04 W/(m K), by hot box measurement or
numerical calculation in accordance with prEN ISO10077-2. The thermal transmittance of the
glazing, U g, is to be determined according to EN 673, EN 674 or EN 675. Both U f and U g thus
exclude the thermal interaction between the frame and the glazing (or opaque panel), which is
taken into account by the linear thermal transmittance, , either tabulated in this standard or
obtained by numerical calculations in accordance with prEN ISO 10077-2 or by measurement
in accordance with prEN 12412-2.
Other values to be used in the basic formulae can be obtained from annex A and
EN 12524 or by means of prEN 1098, EN ISO 6946 and ISO 8302.
If measured or calculated data are not available, the values in informative annexes B to H maybe used.
If the results are to be used for comparison of the performance of different windows, the
sources of the numerical values of each parameter shall be identical for each door or window
included in the comparison.
7 Report
The calculation report shall include the following.
7.1 Drawing of sections
A technical drawing (preferably scale 1:1) giving the sections of all the different frame parts
permitting verification of:
– the thickness, height, position, type and number of thermal breaks (for metallic
frames);
– the number and thickness of air chambers (for plastic frames only);
– the presence and position of metal stiffening (for plastic frames only);
– the thickness of wooden frames and the thickness of plastic and PUR–frame
(polyurethane) material; – the thickness of gas spaces, the identification of the gas and the percentage
assured to be present;
– the type of glass and its thickness or its thermal properties and emissivity of its
surfaces;
– the thickness and description of any opaque panels in the frame;
– the internal projected frame area Af,i and the external projected frame area Af,e;– the internal developed frame area Ad,i and the external developed frame area Ad,e
(only for metallic frames);
– the position of the glass spacers or of the edge stiffening for opaque panels;
description of any shutters.
In the case of metallic frames with pin-point connections the distance between the pinpoints
shall be clearly indicated.
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7.2 Drawing of the whole window or door
A drawing of the whole window or door (seen from inside) with the following information:
– glazed area Ag and/or opaque panel area A
p; – frame area: Af ; – perimeter length of the glazing lg and/or of the opaque panels lp.
7.3 Values used in the calculation
a) If the informative annexes are used this shall be clearly stated and reference shall be
made to the tables in the annexes.
b) If other sources are used to determine one or more of the U g , U f and values, the
sources shall be given. It shall be ascertained that these other sources use the samedefinitions of the areas Ag , Af and of the perimeter length lg and lp.
c) If a glazing not covered by the table in the annex C is used, a detailed calculation
following EN 673 shall be given.
d) If measured or calculated values are used for one of the three parameters the
relevant standards shall be identified and it shall be confirmed that the values obtained
correspond to the definitions of the areas given in this standard.
7.4 Presentation of results
The thermal transmittance of the window or door, calculated according to the standard shall
be given with two significant figures.
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Annex A (normative)
Internal and external surface thermal resistances
For typical normal emissivities (
0,8) for the inside and outside surfaces of the glazing, the
following values for the surface resistances Rse and Rsi shall be used.
Table A.1 - Surface thermal resistances
Window position Internal
Rsim
2 K/W
External
Rsem
2 K/W
Vertical or inclination of the
glazing to the horizontal such that
90° 60°
0,13 0,04
Rsi for special cases, for example a low emissivity coating on the outer surface of the interior
pane, can be calculated according to EN 673.
Annex B (informative)
Thermal conductivity of glass
In the absence of specific information for the glass concerned the value 1,0 W/(m K)
should be used.
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Annex C (informative)
Thermal resistance of air spaces between glazing and thermal transmittance ofcoupled or double glazing
Table C.1 gives some values of the thermal resistance Rs of air spaces for double glazing,
calculated according to EN 673. The data apply:
– for vertical windows or an inclination of the glazing to the horizontal such that
90 ° 60°;
– for spaces filled with air;
– with both sides uncoated or with one side coated with a low emissivity layer;
– for a mean temperature of the glazing of 283 K and a temperature difference of 15 K
between the two outer glazing surfaces.
For triple glazing the procedure in EN 673 should be used.
Table C.1 - Thermal resistance Rs of unventilated air spaces, in m2
K/W, for coupled and
double windows
Thickness of
air space
One side coated with a
normal emissivity of:
Both sides
uncoated
mm 0,1 0,2 0,4 0,8
6 0,211 0,190 0,163 0,132 0,127
9 0,298 0,259 0,211 0,162 0,154
12 0,376 0,316 0,247 0,182 0,173
15 0,446 0,363 0,276 0,197 0,186
50 0,406 0,335 0,260 0,189 0,179
100 0,376 0,315 0,247 0,182 0,173
300 0,333 0,284 0,228 0,171 0,163
For wide air layers like in double windows or doors the calculation according to EN 673 does
not lead to correct results. In such cases more sophisticated calculation methods or
measurements should be used.
Table C.2 gives the thermal transmittance U g of double and triple glazing filled with different
gases, calculated in accordance with EN 673. The values of the thermal transmittance in the
table apply to the emissivities and gas concentrations given. For individual glazing units the
emissivity and/or gas concentration may change with time. Procedures for evaluating the
effect of ageing on the thermal properties of glazed units are given in prEN 1279-1 and
prEN 1279-3.
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Table C.2 - Thermal transmittance U g of double and triple glazing filled with different
gases
Glazing Type of gas space(gas concentration 90 %)
Type GlassNormal
emissivityDimensions
mm Air Argon Krypton SF6
Uncoated 4-6-4 3,3 3,0 2,8 3,0
glass 4-9-4 3,0 2,8 2,6 3,1
(normal 0,89 4-12-4 2,9 2,7 2,6 3,1
glass) 4-15-4 2,7 2,6 2,6 3,1
4-20-4 2,7 2,6 2,6 3,1
One pane 4-6-4 2,9 2,6 2,2 2,6
coated 4-9-4 2,6 2,3 2,0 2,7
glass
0,4 4-12-4 2,4 2,1 2,0 2,74-15-4 2,2 2,0 2,0 2,7
4-20-4 2,2 2,0 2,0 2,7
One pane 4-6-4 2,7 2,3 1,9 2,3
Double coated 4-9-4 2,3 2,0 1,6 2,4
glazing glass 0,2 4-12-4 1,9 1,7 1,5 2,4
4-15-4 1,8 1,6 1,6 2,5
4-20-4 1,8 1,7 1,6 2,5
One pane 4-6-4 2,6 2,2 1,7 2,1
coated 4-9-4 2,1 1,7 1,3 2,2
glass 0,1 4-12-4 1,8 1,5 1,3 2,3
4-15-4 1,6 1,4 1,3 2,34-20-4 1,6 1,4 1,3 2,3
One pane 4-6-4 2,5 2,1 1,5 2,0
coated 4-9-4 2,0 1,6 1,3 2,1
glass 0,05 4-12-4 1,7 1,3 1,1 2,2
4-15-4 1,5 1,2 1,1 2,2
4-20-4 1,5 1,2 1,2 2,2
Uncoated 4-6-4-6-4 2,3 2,1 1,8 2,0
(normal) 0,89 4-9-4-9-4 2,0 1,9 1,7 2,0
glass 4-12-4-12-4 1,9 1,8 1,6 2,0
2 panes 4-6-4-6-4 2,0 1,7 1,4 1,6
coated 0,4 4-9-4-9-4 1,7 1,5 1,2 1,6
4-12-4-12-4 1,5 1,3 1,1 1,6
2 panes 4-6-4-6-4 1,8 1,5 1,1 1,3
Triple coated 0,2 4-9-4-9-4 1,4 1,2 0,9 1,3
glazing 4-12-4-12-4 1,2 1,0 0,8 1,4
2 panes 4-6-4-6-4 1,7 1,3 1,0 1,2
coated 0,1 4-9-4-9-4 1,3 1,0 0,8 1,2
4-12-4-12-4 1,1 0,9 0,6 1,2
2 panes 4-6-4-6-4 1,6 1,3 0,9 1,1
coated 0,05 4-9-4-9-4 1,2 0,9 0,7 1,1
4-12-4-12-4 1,0 0,8 0,5 1,1NOTE The values of thermal transmittance in the table were calculated using EN 673. Theyapply to the emissivities and gas concentration given. For individual glazing units the emissivityand/or gas concentrations may change with time. Procedures for evaluating the effect of ageingon the thermal properties of glazed units are given in prEN 1279-1 and prEN 1279-3.
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Annex D (informative)
Thermal transmittance of frames
Values of U f evaluated by numerical calculation methods (finite element, finite difference) in
accordance with prEN ISO10077-2 can be used as input data for calculations, as can values
of U f obtained by direct measurements using hot box methods in accordance with
prEN 12412-2.
If no other information is available, the values derived from the following tables and graphs
can be used in the calculations for the corresponding frame types.
All values given in this annex refer to the vertical position only. Typical values for common
types of frames are given in table D.1, figure D.2 and figure D.4, which can be used in the
absence of specific measured or calculated information for the frame concerned.
All the values shown in table D.1, figure D.2 and figure D.4 are based on a large number of
measured values as well as mathematically evaluated values determined using numerical
calculation methods. They include the effect of the developed areas.
Future development should not be impeded by tabulated U f values. Values for frames which
are not described in the tables should be determined by measurements or calculations.
Especially in the case of aluminium profiles with thermal breaks1) there is the problem that the
thermal transmittance of the frame is influenced by different construction characteristics, such
as: – the distance a between the aluminium sections;
– the width b of the material of the thermal break zones;
– the conductivity of the thermal break material;
– the ratio of the width of the thermal break to the frame projection width.
A thermal break can be considered as such only if it completely separates the metal sections
on the cold side from the metal sections on the warm side.
The values in this annex are based on Rsi = 0,13 m2
K/W and Rse = 0,04 m2
K/W.
It is common practice to produce "Profile Systems" comprising a large number of different
frames, having a wide range of geometric shapes but having similar thermal properties. This is
because in these groups of frames, the important parameters such as the size, material and
design of the thermal break, are the same. A document specifying practical procedures for
evaluating the thermal properties of such "profile systems" is under preparation.
1) The values of U f in table D.1, figure D.2 and figure D.4 cannot be used for sliding windows but theprinciple of equation (1) can be used.
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Page 21EN ISO 10077-1:2000
Plastic frames
If no other data are available, the values in table D.1 can be used for frames without metal
reinforcements.
Table D.1 - Thermal transmittances for plastic frames with metal reinforcements
Frame material Frame type U f W/(m2 K)
Polyurethane with metal core
thickness of PUR 5 mm
2,8
PVC-hollow
profiles1)
two hollow chambers
2,2
three hollow chambers
2,0
1)
With a distance between wall surfaces of hollow chambers of at least 5 mm (refer to figure D.1).
Dimensions in millimetres
Figure D.1 - Hollow chamber in plastic frame
Other plastic profile sections should be measured or calculated.
5
external
external
internal
internal
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Page 22EN ISO 10077-1:2000
Wood frames
Values for wood frames can be taken from figure D.2. For U f , the values correspond to amoisture content of 12 %. For definition of the thickness of the frame see figure D.3.
hard wood (density 700 kg/m3) = 0,18 W/(m K)
soft wood (density 500 kg/m3)
= 0,13 W/(m
K)
Thickness of the frame d f in mm
U f in (W/m
2
K)
2,0
1,0
3,0
15010050
Figure D.2 - Thermal transmittances for wooden frames and metal-wood frames (see figure D.3)depending on the frame thickness d f
sash
frame
wood metal-wood metal-wood internal:
right side offrame section
external:left side offrame section
d 1 d 1
d 2 d 2 d 2
d 1
2
21f
d d d
sash
frame
wood wood metal-wood
d d d j j
f
sa f
2
d 1
d 3d 2
d 1
d 3d 2
d 1
d 4d 2 d 3
Figure D.3 - Definition of the thickness d f of the frame for various window systems
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Page 23EN ISO 10077-1:2000
Metal frames
The thermal transmittance of metal frames can be determined by measurement using hot boxmethods in accordance with prEN 12412-2 or by numerical calculation
in accordance with
prEN ISO 10077-2. Values obtained by such methods should be used when available, in
preference to the method given in this annex.
If such data are not available, values of U f can be obtained by the following procedure for:
- metal frames without a thermal break;- metal frames with thermal breaks corresponding to the sections illustrated in figure D.5
and figure D.6, subject to restrictions on the thermal conductivity and widths of thethermal breaks.
For metal frames without a thermal break, use U fo = 5,9 W/(m2·K).
For metal frames with thermal breaks, take U fo from the solid line in figure D.4.
4 0
3 0
2,0
0 4 8 12 16 20 24 28
U fo in W/(m2·K)
32 36
Smallest distance between opposite metal sections, d , in mm
NOTE The shaded area indicates the range of values obtained from manymeasurements on frames carried out in several European countries, derived from thesurface temperature difference across the frame.
Figure D.4 - U f0 -values for metal frames with thermal break
The thermal resistance of the frame, Rf , is given by
17,01
f0f
U R (D.1)
and the thermal transmittance of the frame, U f , from
ed,ef,sef id,if,si / /
1f A A R R A A R
U
(D.2)
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Page 24EN ISO 10077-1:2000
where Ad,i, Ad,e, Af,i, Af,e, are the areas as defined in clause 4, expressed in square metres;
Rsi is the appropriate internal surface resistance of the frame, in m2
K/W;
Rse is the appropriate external surface resistance of the frame, in m2
K/W;
Rf is the thermal resistance of the frame section, in m2
K/W, resulting from the thermal
transmittance of the frame taking into account the appropriate surface resistance.U f0 is the thermal transmittance, in W/(m
2 K), calculated as if the developed area were
equal to the projected area.
d is the smallest distance between
opposite aluminium sections of
the thermal break; b j is the width of thermal break j;
bf is the width of the frame.
f 0,2bb j
j
Thermal conductivity of thermal
break materials
0,2
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Page 25EN ISO 10077-1:2000
Annex E (informative)
Linear thermal transmittance of frame/glazing junction
The thermal transmittance of the glazing, U g, is applicable to the central area of the glazing
and does not include the effect of the glass spacers at the edge of the glazing. On the other
hand, the thermal transmittance of the frame, U f , is applicable in the absence of the glazing.
The linear thermal transmittance describes the additional heat conduction due to the
interaction between frame, glazing and spacer. The linear transmittance is mainly effected
by the conductivity of the spacer material. For aluminium and steel (not stainless steel) glass
spacers table E.1 indicates the values of for a specific range of types of frames and glazing.
Table E.1 - Values of the linear thermal transmittance,
2 ), for aluminium and steel (not stainless
steel) glass spacers
Frame material Double or triple glazing,
uncoated glass,
air or gas space
W/(m·K)
Double glazing with low emissivity,
triple glazing with two low emissivity
coatings, air or gas space
W/(m·K)
Wood frame and
plastic frame
0,04 0,06
Metal frame with
thermal break
0,06 0,08
Metal frame without
thermal break
0 0,02
Values for spacers not covered by the table can be determined by numerical calculation in
accordance with prEN ISO 10077-2.
2) These values are evaluated for double glazings with low emissivity, U g 1,3 W/(m
2 K) and triple
glazing with low emissivity U g 0,7 W/(m2
K).
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Annex F (informative)
Thermal transmittance of windows
Table F.1 and table F.2 give typical values calculated by the method in this standard using
linear thermal transmittances from annex E. Values for windows with other frame area
fractions can be evaluated by means of the equations of the main part of that standard.
Table F.1 - Thermal transmittances for windows with fraction of the frame area 30 % of the whole
window area
Type of
glazing
U g
W/(m K)
U f
W/(m K)
frame area 30 %
1,0 1,4 1,8 2,2 2,6 3,0 3,4 3,8 7,0
Single 5,7 4,3 4,4 4,5 4,6 4,8 4,9 5,0 5,1 6,1
3,3 2,7 2,8 2,9 3,1 3,2 3,4 3,5 3,6 4,4
3,1 2,6 2,7 2,8 2,9 3,1 3,2 3,3 3,5 4,3
2,9 2,4 2,5 2,7 2,8 3,0 3,1 3,2 3,3 4,1
2,7 2,3 2,4 2,5 2,6 2,8 2,9 3,1 3,2 4,0
2,5 2,2 2,3 2,4 2,6 2,7 2,8 3,0 3,1 3,9
2,3 2,1 2,2 2,3 2,4 2,6 2,7 2,8 2,9 3,8
Double 2,1 1,9 2,0 2,2 2,3 2,4 2,6 2,7 2,8 3,6
1,9 1,8 1,9 2,0 2,1 2,3 2,4 2,5 2,7 3,5
1,7 1,6 1,8 1,9 2,0 2,2 2,3 2,4 2,5 3,3
1,5 1,5 1,6 1,7 1,9 2,0 2,1 2,3 2,4 3,2
1,3 1,4 1,5 1,6 1,7 1,9 2,0 2,1 2,2 3,1
1,1 1,2 1,3 1,5 1,6 1,7 1,9 2,0 2,1 2,9
2,3 2,0 2,1 2,2 2,4 2,5 2,7 2,8 2,9 3,7
2,1 1,9 2,0 2,1 2,2 2,4 2,5 2,6 2,8 3,6
1,9 1,7 1,8 2,0 2,1 2,3 2,4 2,5 2,6 3,4
Triple 1,7 1,6 1,7 1,8 1,9 2,1 2,2 2,4 2,5 3,3
1,5 1,5 1,6 1,7 1,9 2,0 2,1 2,3 2,4 3,2
1,3 1,4 1,5 1,6 1,7 1,9 2,0 2,1 2,2 3,1
1,1 1,2 1,3 1,5 1,6 1,7 1,9 2,0 2,1 2,9
0,9 1,1 1,2 1,3 1,4 1,6 1,7 1,8 2,0 2,8
0,7 0,9 1,1 1,2 1,3 1,5 1,6 1,7 1,8 2,6
0,5 0,8 0,9 1,0 1,2 1,3 1,4 1,6 1,7 2,5
NOTE The calculation has been made using -values according to annex E. Values for windows
with frame area fractions not equal to 30 % have to be evaluated by means of the equations of the
main part of the standard.
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Table F.2 - Thermal transmittances for windows with fraction of the frame area 20 % of the whole
window area
Type ofglazing
U g
W/(m K)
U f
W/(m K)
frame area 20 %
1,0 1,4 1,8 2,2 2,6 3,0 3,4 3,8 70
Single 5,7 4,8 4,8 4,9 5,0 5,1 5,2 5,2 5,3 5,9
3,3 2,9 3,0 3,1 3,2 3,3 3,4 3,4 3,5 4,0
3,1 2,8 2,8 2,9 3,0 3,1 3,2 3,3 3,4 3,9
2,9 2,6 2,7 2,8 2,8 3,0 3,0 3,1 3,2 3,7
2,7 2,4 2,5 2,6 2,7 2,8 2,9 3,0 3,0 3,6
2,5 2,3 2,4 2,5 2,6 2,7 2,7 2,8 2,9 3,4
2,3 2,1 2,2 2,3 2,4 2,5 2,6 2,7 2,7 3,3
Double 2,1 2,0 2,1 2,2 2,2 2,3 2,4 2,5 2,6 3,1
1,9 1,8 1,9 2,0 2,1 2,2 2,3 2,3 2,4 3,0
1,7 1,7 1,8 1,8 1,9 2,0 2,1 2,2 2,3 2,8
1,5 1,5 1,6 1,7 1,8 1,9 1,9 2,0 2,1 2,6
1,3 1,4 1,4 1,5 1,6 1,7 1,8 1,9 2,0 2,5
1,1 1,2 1,3 1,4 1,4 1,5 1,6 1,7 1,8 2,3
2,3 2,1 2,2 2,3 2,4 2,5 2,6 2,6 2,7 3,22,1 2,0 2,0 2,1 2,2 2,3 2,4 2,5 2,6 3,1
1,9 1,8 1,9 2,0 2,0 2,2 2,2 2,3 2,4 2,9
Triple 1,7 1,6 1,7 1,8 1,9 2,0 2,1 2,2 2,2 2,8
1,5 1,5 1,6 1,7 1,8 1,9 1,9 2,0 2,1 2,6
1,3 1,4 1,4 1,5 1,6 1,7 1,8 1,9 2,0 2,5
1,1 1,2 1,3 1,4 1,4 1,5 1,6 1,7 1,8 2,3
0,9 1,0 1,1 1,2 1,3 1,4 1,5 1,6 1,6 2,2
0,7 0,9 1,0 1,0 1,1 1,2 1,3 1,4 1,5 2,0
0,5 0,7 0,8 0,9 1,0 1,1 1,2 1,2 1,3 1,8
NOTE The calculation has been made using - values according to annex E. Values for windows
with frame area fractions not equal to 20 % have to be evaluated by means of the equations of the
main part of the standard.
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Annex G (informative)
Additional thermal resistance for windows with closed shutters
When the thermal resistance of the shutter itself, Rsh, is known (by calculation or by
measurement) the additional thermal resistance, R, should be obtained using the appropriateexpression in 5.3. Table G.1 gives some typical values of shutter thermal resistance and thecorresponding values of
R, which can be used in the absence of values of Rsh obtained frommeasurement or calculation.
Table G.1 - Additional thermal resistance,
R, for windows with closed shutters
Shutter type Typical
thermal
resistance of
shutter Rsh
m2
K/W
Additional thermal resistances
at specific air permeability of the
shutters 1)
Rm
2 K/W
High air
permeability
Average air
permeability
Low air
permeability
Roller shutters of
aluminium0,01 0,09 0,12 0,15
Roller shutters of
wood and plastic
without foam filling
0,10 0,12 0,16 0,22
Roller shutters of
plastic with foam
filling
0,15 0,13 0,19 0,26
Shutters of wood,
25 mm to 30 mm
thickness
0,20 0,14 0,22 0,30
1)
The definition of the air permeability of shutters is given in annex H.
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Annex H (informative)
Permeability of shutters
For the different types of shutter, the permeability criterion can be expressed in terms of an
effective total gap bsh between the shutter and its surround according to figure H.1.
shb b b b 1 2 3 (H.1)
where b1 , b2 and b3 are the average edge gaps at the bottom, top and side on the shutter (seefigure H.1).
b3 is included for one side only, since gaps at the side influence the permeability less than thegaps at the top and bottom.
b 3
internal
external
b 2
b 1
shutter
b 2
b 1
external internal
b 3
Figure H.1 - Definition of edge gaps
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Table H.1 - Relationship between permeability and effective total edge gap between shutter andits surround
Class Permeability of shutter bsh
mm
1 Very high permeability bsh > 35
2 High air permeability 15 bsh < 35
3 Average air permeability 8 bsh < 15
4 Low air permeability bsh 8
5 Tight bsh 3 and b1+b3=0 or b2+b3= 0
NOTE 1 For permeability classes 2 and above, there should be no openings within theshutter itself.
NOTE 2 For shutters of permeability class 5 the following criteria apply:
a) Roller shutters
The edge gaps at the sides and the bottom are considered equal to 0 if strip gaskets are
supplied in the guide rails and the final lath, respectively. The gap at the top is considered
equal to 0 if the entrance to the roller shutter box is fitted with lips - or brush-type joints on
both sides of the curtain or if the end of the curtain is pressed by a device (spring) against
a sealing material at the inner surface of the outer side of the roller shutter box.
b) Other shutters
Effective presence of strip gaskets on three sides and the gap at the fourth side less than
3 mm.
An alternative method to establish that a shutter is class 5 is to verify by measurement that the
air flow through the shutter is less or equal than 10 m3 /(h m
2) under a pressure drop of
10 Pa.
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Annex ZA (informative)
A-deviations
A-deviation: National deviation due to regulations, the alteration of which is
for the time being outside the competence of the CEN/CENELEC member.
This European Standard does not fall under any Directive of the EC.
In the relevant CEN/CENELEC countries these A-deviations are valid instead ofthe provisions of the European Standard until they have been removed.
Clause Deviation
6 Germany: Verordnung über einen energiesparendenWärmeschutz bei Gebäuden (Wärmeschutzverordnung -WärmeschutzV) Vom 16. August 1994.
The German regulation specifies that the design thermaltransmittance for glazing as well as windows and windowdoors shall be in accordance with tables 2 to 6 ofDIN V 4108-4:1998-10.
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BS EN ISO10077-1:2000
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