EN ISO 10077-2:2012

SLOVENSKI STANDARD
01-junij-2012
1DGRPHãþD
SIST EN ISO 10077-2:2004
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Thermal performance of windows, doors and shutters - Calculation of thermal
transmittance - Part 2: Numerical method for frames (ISO 10077-2:2012)
Wärmetechnisches Verhalten von Fenstern, Türen und Abschlüssen - Berechnung des
Wärmedurchgangskoeffizienten - Teil 2: Numerisches Verfahren für Rahmen (ISO 10077
-2:2012)
Performance thermique des fenêtres, portes et fermetures - Calcul du coefficient de
transmission thermique - Partie 2: Méthode numérique pour les encadrements (ISO
10077-2:2012)
Ta slovenski standard je istoveten z: EN ISO 10077-2:2012
ICS:
91.060.50 Vrata in okna Doors and windows
91.120.10 Toplotna izolacija stavb Thermal insulation
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN ISO 10077-2
NORME EUROPÉENNE
EUROPÄISCHE NORM
February 2012
ICS 91.060.50; 91.120.10 Supersedes EN ISO 10077-2:2003
English Version
Thermal performance of windows, doors and shutters -
Calculation of thermal transmittance - Part 2: Numerical method
for frames (ISO 10077-2:2012)
Performance thermique des fenêtres, portes et fermetures - Wärmetechnisches Verhalten von Fenstern, Türen und
Calcul du coefficient de transmission thermique - Partie 2: Abschlüssen - Berechnung des
Méthode numérique pour les encadrements (ISO 10077- Wärmedurchgangskoeffizienten - Teil 2: Numerisches
2:2012) Verfahren für Rahmen (ISO 10077-2:2012)
This European Standard was approved by CEN on 29 February 2012.

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, Turkey and United Kingdom.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2012 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 10077-2:2012: E
worldwide for CEN national Members.

Contents Page
Foreword .3

Foreword
This document (EN ISO 10077-2:2012) has been prepared by Technical Committee ISO/TC 163 "Thermal
performance and energy use in the built environment" in collaboration with Technical Committee CEN/TC 89
“Thermal performance of buildings and building components” the secretariat of which is held by SIS.
This European Standard shall be given the status of a national standard, either by publication of an identical
text or by endorsement, at the latest by August 2012, and conflicting national standards shall be withdrawn at
the latest by August 2012.
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 ISO 10077-2:2003.
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, Turkey and the United Kingdom.
Endorsement notice
The text of ISO 10077-2:2011 has been approved by CEN as a EN ISO 10077-2:2012 without any
modification.
INTERNATIONAL ISO
STANDARD 10077-2
Second edition
2012-03-01
Thermal performance of windows, doors
and shutters — Calculation of thermal
transmittance —
Part 2:
Numerical method for frames
Performance thermique des fenêtres, portes et fermetures — Calcul du
coefficient de transmission thermique —
Partie 2: Méthode numérique pour les encadrements
Reference number
ISO 10077-2:2012(E)
©
ISO 2012
ISO 10077-2:2012(E)
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISO’s
member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2012 – All rights reserved

ISO 10077-2:2012(E)
Contents Page
Foreword .iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and symbols . 1
4 Calculation method . 2
4.1 General principle . 2
4.2 Validation of the calculation programme . 3
4.3 Determination of the thermal transmittance . 3
5 Treatment of solid sections and boundaries . 3
5.1 Solid materials . 3
5.2 Emissivity of surfaces . 3
5.3 Boundaries . 4
5.4 Roller shutter boxes . 4
5.5 Extensions of window frame profiles . 6
6 Treatment of cavities . 6
6.1 General . 6
6.2 Cavities in glazing . 6
6.3 Unventilated air cavities in frames and roller shutter boxes . 6
6.4 Ventilated air cavities and grooves .10
7 Report . 11
7.1 General . 11
7.2 Geometrical data .12
7.3 Thermal data .12
7.4 Results .12
Annex A (informative) Thermal conductivity of selected materials .13
Annex B (normative) Surface resistances .15
Annex C (normative) Determination of the thermal transmittance .17
Annex D (normative) Examples for the validation of calculation programmes .21
Annex E (informative) Wood species listed in Annex A .33
Bibliography .36
ISO 10077-2:2012(E)
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 10077-2 was prepared by Technical Committee ISO/TC 163, Thermal performance and energy use in the
built environment, Subcommittee SC 2, Calculation methods, in collaboration with the European Committee for
Standardization (CEN) Technical Committee CEN/TC 89, Thermal performance of buildings and building components,
in accordance with the Agreement on technical cooperation between ISO and CEN (Vienna Agreement).
This International Standard is one of a series of standards on methods for the design and evaluation of the
thermal performance of building equipment and industrial installations.
This second edition cancels and replaces the first edition (ISO 10077-2:2003), which has been technically
revised. The main changes compared to the previous edition are given in the following table:
Clause Changes
5.1 Clarified use of measured data.
5.4 Added calculation rules for roller shutter boxes and added new figure.
5.5 Added calculation rules for extensions of window frame profiles and new added figure.
Annex A Added Table A.2 — Thermal conductivity of timber species.
Annex A Added Table A.3 — Typical emissivities of metallic surfaces.
Annex B Added Table B.2 for roller shutter boxes.
C.2 Added calculation rules for the combination of frame constructions with insulating
glazing units (IGU) and Figure C.3 showing a representative metal spacer incorporated
in an IGU.
Annex D Updated Figures D.1 to D.10 for frame sections.
ISO 10077 consists of the following parts, under the general title Thermal performance of windows, doors and
shutters — Calculation of thermal transmittance:
— Part 1: General
— Part 2: Numerical method for frames
iv © ISO 2012 – All rights reserved

ISO 10077-2:2012(E)
Introduction
ISO 10077 consists of two parts. The method in this part of ISO 10077 is intended to provide calculated values
of the thermal characteristics of frame profiles, suitable to be used as input data in the calculation method of
the thermal transmittance of windows, doors and shutters given in ISO 10077-1. It is an alternative to the test
method specified in EN 12412-2. In some cases, the hot box method is preferred, especially if physical and
geometrical data are not available or if the profile is a complicated geometrical shape.
Although the method in this part of ISO 10077 basically applies to vertical frame profiles, it is an acceptable
approximation for horizontal frame profiles (e.g. sill and head sections) and for products used in sloped
positions (e.g. roof windows). For calculations made with the glazing units in place, the heat flow pattern and
the temperature field within the frame are useful by-products of this calculation.
This part of ISO 10077 does not cover building façades and curtain walling. These are covered in
1)
ISO 12631 or EN 13947.
1) To be published.
INTERNATIONAL STANDARD ISO 10077-2:2012(E)
Thermal performance of windows, doors and shutters —
Calculation of thermal transmittance —
Part 2:
Numerical method for frames
1 Scope
This part of ISO 10077 specifies a method and gives reference input data for the calculation of the thermal
transmittance of frame profiles and of the linear thermal transmittance of their junction with glazing or opaque panels.
The method can also be used to evaluate the thermal resistance of shutter profiles and the thermal characteristics
of roller shutter boxes and similar components (e.g. blinds).
This part of ISO 10077 also gives criteria for the validation of numerical methods used for the calculation.
This part of ISO 10077 does not include effects of solar radiation, heat transfer caused by air leakage or
three-dimensional heat transfer such as pin point metallic connections. Thermal bridge effects between the
frame and the building structure are not included.
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 7345, Thermal insulation — Physical quantities and definitions
ISO 10211, Thermal bridges in building construction — Heat flows and surface temperatures — Detailed calculations
ISO 10456: 2007, Building materials and products — Hygrothermal properties — Tabulated design values and
procedures for determining declared and design thermal values
ISO 12567-2:2005, Thermal performance of windows and doors — Determination of thermal transmittance by
hot box method — Part 2: Roof windows and other projecting windows
ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories
EN 673, Glass in building — Determination of thermal transmittance (U-value) — Calculation method
EN 12519, Windows and pedestrian doors — Terminology
3 Terms, definitions and symbols
For the purposes of this document, the terms and definitions given in ISO 7345 and EN 12519 apply.
ISO 10077-2:2012(E)
Symbol Definition Unit
A
area m
b
width, i.e. perpendicular to the direction of heat flow m
d depth, i.e. parallel to the direction of heat flow m
E intersurface emittance —
F view factor —
h
heat transfer coefficient W/(m ·K)
2D
L two-dimensional thermal conductance or thermal coupling coefficient W/(m·K)
l length m
q density of heat flow rate W/m
R
thermal resistance m ·K/W
T
thermodynamic temperature K
U thermal transmittance W/(m ·K)
2 4
σ Stefan-Boltzmann constant W/(m ·K )
ε emissivity —
λ
thermal conductivity W/(m·K)
Ψ linear thermal transmittance W/(m·K)
Subscripts
a convective (surface to surface)
e external (outdoor)
g glazing
eq equivalent
f frame
fr frame adjacent to roller shutter box
i internal (indoor)
p panel
r radiative
s space (air or gas space)
sb shutter box
se external surface
si internal surface
4 Calculation method
4.1 General principle
The calculation shall be carried out using a two-dimensional numerical method conforming to ISO 10211. The
elements shall be divided such that any further division does not change the calculated result significantly.
ISO 10211 gives criteria for judging whether sufficient sub-divisions have been used.
Vertical orientation of frame sections and air cavities is assumed for calculations using this part of ISO 10077
for the purposes of assigning equivalent thermal conductivity values (see 7.3); this applies irrespective of the
intended orientation of the actual window, including roof windows.
2 © ISO 2012 – All rights reserved

ISO 10077-2:2012(E)
4.2 Validation of the calculation programme
To ensure the suitability of the calculation programme used, calculations shall be carried out on the examples
2D
described in Annex D. The calculated two-dimensional thermal conductance L shall not differ from the
corresponding values given in Table D.3 by more than ±3 %. This will lead to an accuracy of the thermal
transmittance, U, and the linear thermal transmittance Ψ, of about 5 %.
NOTE The ± deviations in Tables D.3 and D.4 are standard deviations from a round-robin and are not to be confused
with ±3 % specified above.
4.3 Determination of the thermal transmittance
The thermal transmittance of a frame section shall be determined with the glazing replaced by an insulating
panel according to Annex C, with the external and internal surface resistances taken from Annex B. The linear
thermal transmittance of the interaction of frame and glazing shall be determined from calculations with the
glazing in place and with the glazing replaced by an insulated panel.
NOTE 1 The interaction of the frame and the building structure is considered separately for the building as a whole. It
is not part of the thermal transmittance of the frame section.
NOTE 2 In the case of an overlap between the frame section and part of the wall, the linear thermal transmittance
could be negative.
5 Treatment of solid sections and boundaries
5.1 Solid materials
For the purpose of this part of ISO 10077, thermal conductivity values used for solid materials shall be obtained
according to one of the following:
— Table A.1 of this part of ISO 10077;
— tabulated values given in ISO 10456;
— product standards;
— technical approvals by a recognized national body;
— measurements according to an appropriate International Standard.
Measurements shall be used only if there is no tabulated data or data according to relevant product standards or
a technical approval. Measurements shall be performed at a mean temperature of 10 °C using the appropriate
method by an institute accredited (as specified in ISO/IEC 17025) to carry out those measurements, on samples
that have been conditioned at 23 °C and 50 % RH to constant mass (change in mass not more than 0,1 % over
24 h). To ensure that the thermal conductivity values are representative of the material (that is, that the value
incorporates likely variability of the material and the measurement uncertainty), one of the following methods
shall be used for obtaining the thermal conductivity value from measured data used in the calculations:
— The thermal conductivity is the declared value obtained from the measured data (at least three different
samples from different lots representing the usual product variation, with ageing taken into consideration)
according to a statistical evaluation as defined in ISO 10456: 2007, Annex C, 90 % fractile.
— If less than three samples, use the mean value multiplied by a factor of 1,25.
5.2 Emissivity of surfaces
Normally, the emissivity of surfaces bounding an air cavity shall have an emissivity of 0,9. Metallic surfaces
such as aluminium alloy frame, steel reinforcement and other metals/alloys have lower emissivity. Typical
values of the emissivity for metallic surfaces are given in Table A.3. Values less than 0,9 may be used only if
taken from Table A.3 or measured in accordance with an appropriate standard by an institute accredited (as
ISO 10077-2:2012(E)
specified in ISO/IEC 17025) to carry out those measurements. Where based on measured values there shall
be at least three samples and the results shall be evaluated according to the statistical treatment in ISO 10456.
5.3 Boundaries
The external and internal surface resistances depend on the convective and radiative heat transfer to the external
and internal environments. If an external surface is not exposed to normal wind conditions, the convective part
may be reduced in edges or junctions between two surfaces. The surface resistances for horizontal heat flow
are given in Annex B. These values shall be used for calculations by this part of ISO 10077 irrespective of the
intended orientation of the actual window, including roof windows. Surface condensation shall be assessed
on the basis of the lowest internal surface temperature calculated using the surface resistances in Annex B.
The cutting plane of the infill and the cutting plane to neighbouring material shall be taken as adiabatic
(see Figure 3 and Annex D)
The reference temperature conditions shall be 20 °C internal and 0 °C external.
5.4 Roller shutter boxes
Calculation of the thermal transmittance of a roller shutter box shall be done with the following boundary conditions:
— the top of the roller shutter box: adiabatic;
— the bottom of the roller shutter box where it adjoins the window frame: adiabatic for a distance of 60 mm;
— surfaces adjacent to the internal environment: surface resistance of 0,13 m ·K/W;
— surfaces adjacent to the external environment: surface resistance of 0,04 m ·K/W.
The cavity within the roller shutter box shall be treated as (see Figure 1):
— if e + e ≤ 2 mm: unventilated. The equivalent thermal conductivity of an unventilated air cavity is
1 3
calculated according to 6.3. Additional hardware, e.g. brushes, gaskets etc., can be taken into account for
determination of e and e ;
1 3
— if e ≤ 35 mm: slightly ventilated. The equivalent thermal conductivity is twice that of an unventilated cavity
tot
of the same size;
— if e > 35 mm: well ventilated taking the air temperature within the cavity equal to the external air
tot
temperature but with a surface resistance of 0,13 m ·K/W.
The relevant height of the roller shutter box, b , used for the calculation is the projected distance between the
sb
upper and lower adiabatic boundary (see Figure 1).
The assessment may be done with insulation on either or both of the boundaries B and C indicated in Figure 1. If
that is the case, the thickness and thermal conductivity of the insulation shall be stated in the calculation report.
4 © ISO 2012 – All rights reserved

ISO 10077-2:2012(E)
Dimensions in millimetres
Key
Boundaries (see Annex B):
A adiabatic boundary
B external surface resistance
C internal surface resistance
b height of the roller shutter box
sb
e , e widths of air gaps on either side of the shutter where it exits from the shutter box
1 3
e thickness of shutter
e e + e + e
tot 1 2 3
l frame length
fr
NOTE The window frame (boundary A) is 60 mm wide but located with respect to the roller shutter box according to the
ISO 10077-2:2012(E)
actual situation.
Figure 1 — Schematic example for the treatment of the boundaries for roller shutter boxes
5.5 Extensions of window frame profiles
For frames with special extensions overlapping the wall or other building elements, such as Z-shaped profiles,
the extensions shall be disregarded as illustrated in Figure 2. This applies to all profiles with special extensions
(e.g. H-shape) where the extensions overlap the wall or other building elements. Other boundaries shall be
treated as defined in Figure 3.
Figure 2 — Treatment of profiles with extensions (Z-shape)
NOTE 1 This approximation is for assessment of thermal transmittance. It is not appropriate for assessment of
condensation risk.
NOTE 2 The extension of the frame profile is disregarded in the calculation of the thermal transmittance of the window
(see ISO 10077-1).
6 Treatment of cavities
6.1 General
The heat flow rate in cavities shall be represented by an equivalent thermal conductivity λ . This equivalent
eq
thermal conductivity includes the heat flow by conduction, by convection and by radiation, and depends on the
geometry of the cavity and on the adjacent materials.
6.2 Cavities in glazing
The equivalent thermal conductivity of an unventilated space between glass panes in glazing shall be determined
according to EN 673. The resulting equivalent conductivity shall be used in the whole cavity, up to the edge.
NOTE The correlations for high aspect ratio cavities used in EN 673 tend to give low values for the equivalent thermal
conductivity. More accurate correlations are given in ISO 15099.
6.3 Unventilated air cavities in frames and roller shutter boxes
6.3.1 Definition
Air cavities are unventilated if they are completely closed or connected either to the exterior or to the interior
by a slit with a width not exceeding 2 mm (see Figure 3). Otherwise, the cavity shall be treated as ventilated.
6 © ISO 2012 – All rights reserved

ISO 10077-2:2012(E)
Dimensions in millimetres
Key
Boundaries (see Annex B): Cavities and grooves:
A adiabatic boundary
B external surface resistance
C internal surface resistance
D increased surface resistance
E glazing (see 6.2)
F unventilated cavity (see 6.3)
G slightly ventilated cavity or groove (see 6.4.1)
H well ventilated cavity or groove (see 6.4.2)
Figure 3 — Schematic example for the treatment of cavities and grooves
of a frame section and the treatment of the boundaries
NOTE Figure 3 illustrates a window. The same principles are applicable to roof windows, but the adiabatic part of the
boundary is different; an example of a roof window is shown in Figure D.5.
ISO 10077-2:2012(E)
6.3.2 Unventilated rectangular cavities
6.3.2.1 Equivalent thermal conductivity
The equivalent thermal conductivity λ of the cavity in direction 1 is given by Equation (1).
eq
d
λ = (1)
eq
R
s
where
d is the dimension of the cavity in the direction of heat flow (see Figure 2);
R is the thermal resistance of the cavity, given by Equation (2):
s
R = (2)
s
hh+
ar
where
h is the convective heat transfer coefficient;
a
h is the radiative heat transfer coefficient.
r
Key
1 heat flow direction
b dimension perpendic
...