EN ISO 10077-2:2017/A1:2025

Thermal performance of windows, doors and shutters - Calculation of thermal transmittance - Part 2: Numerical method for frames - Amendment 1 (ISO 10077-2:2017/Amd1:2024)

Wärmetechnisches Verhalten von Fenstern, Türen und Abschlüssen - Berechnung des Wärmedurchgangskoeffizienten - Teil 2: Numerisches Verfahren für Rahmen - Änderung 1 (ISO 10077 2:2017/Amd 1:2024)

Performance thermique des fenêtres, portes et fermetures - Calcul du coefficient de transmission thermique - Partie 2: Méthode numérique pour les encadrements - Amendement 1 (ISO 10077-2:2017/Amd1:2024)

Toplotne značilnosti oken, vrat in polken - Izračun toplotne prehodnosti - 2. del: Računska metoda za okvirje - Dopolnilo 1 (ISO 10077-2:2017/Amd1:2024)

General Information

• Status: Published
• Publication Date: 07-Jan-2025
• ICS: 91.060.50 - Doors and windows
• ICS: 91.120.10 - Thermal insulation of buildings
• Technical Committee: CEN/TC 89 - Thermal performance of buildings and building components
• Drafting Committee: CEN/TC 89 - Thermal performance of buildings and building components
• Current Stage: 6060 - Definitive text made available (DAV) - Publishing
• Start Date: 08-Jan-2025
• Completion Date: 08-Jan-2025
• Ref Project: SIST EN ISO 10077-2:2017/A1:2025 - Thermal performance of windows, doors and shutters - Calculation of thermal transmittance - Part 2: Numerical method for frames - Amendment 1 (ISO 10077-2:2017/Amd1:2024)

Relations

• Amends: EN ISO 10077-2:2017 - Thermal performance of windows, doors and shutters - Calculation of thermal transmittance - Part 2: Numerical method for frames (ISO 10077-2:2017)
• Effective Date: 20-Oct-2021

Overview

EN ISO 10077-2:2017/A1:2025 is Amendment 1 to ISO 10077-2:2017 - the internationally used method for calculating the thermal transmittance (U‑value) of window, door and shutter frames using numerical modelling. Prepared under ISO/TC 163 and adopted by CEN, this amendment (ISO 10077-2:2017/Amd1:2024) was approved by CEN on 8 November 2024 and published as EN ISO 10077-2:2017/A1:2025. The update refines figures, example cases and input keys to improve clarity and alignment with EPB (Energy Performance of Buildings) standards.

Key topics and technical updates

• Numerical method for frames: Continued focus on the 2D numerical calculation approach for thermal transmittance of frame cross-sections (frame U and linear thermal transmittance L).
• Updated figures and keys: Many figures in Annexes F, H and I are replaced or extended with explicit keys identifying boundaries, materials (aluminium, PVC, wood, polyamide, EPDM, insulation panels), surface emissivities and adiabatic/internal/external surface resistance designations.
• Boundary and surface resistance clarifications: Table H.1 (boundaries) is updated to show adiabatic, external and internal surface resistances and associated temperatures or references to Annex E.
• Example cases and results: Annex H example profiles (Figures H.1–H.11) are revised and Table H.3 gives calculated thermal conductance (L) and frame thermal transmittance (Uf) values for those examples - values are provided to three significant figures to avoid rounding errors.
• Emissivity and material notes: Default emissivity values are specified (commonly 0.9; exceptions noted such as 0.1 in a specific figure), and projected frame widths for sample sections are listed where relevant.
• EPB harmonization: The amendment makes explicit that no optional choices are left open in this document, ensuring congruence with other EPB-related standards.

Applications and who uses it

• Window/door manufacturers: For product design, thermal optimisation and documentation of frame U‑values required for energy labelling and compliance.
• Thermal engineers and facade consultants: To calculate frame heat losses reliably using standardized 2D numerical methods.
• Test laboratories and certification bodies: For reproducible calculation methods used in compliance testing and certification of window/door systems.
• Regulatory authorities and energy assessors: To support building energy performance assessments and regulatory compliance where frame thermal transmittance contributes to overall glazing/element U‑values.

Related standards

• ISO 10077 series (Part 1 covers glazing calculation; Part 2 focuses on frames)
• EPB-related CEN standards for building energy performance and product declarations

Keywords: thermal performance, windows doors shutters, thermal transmittance, U‑value, numerical method for frames, EN ISO 10077-2 amendment, frame thermal calculation, CEN, ISO, energy performance.

Standards Content (Sample)

SLOVENSKI STANDARD
01-marec-2025
Toplotne značilnosti oken, vrat in polken - Izračun toplotne prehodnosti - 2. del:
Računska metoda za okvirje - Dopolnilo 1 (ISO 10077-2:2017/Amd1:2024)
Thermal performance of windows, doors and shutters - Calculation of thermal
transmittance - Part 2: Numerical method for frames - Amendment 1 (ISO 10077-
2:2017/Amd1:2024)
Wärmetechnisches Verhalten von Fenstern, Türen und Abschlüssen - Berechnung des
Wärmedurchgangskoeffizienten - Teil 2: Numerisches Verfahren für Rahmen - Änderung
1 (ISO 10077-2:2017/Amd1:2024)
Performance thermique des fenêtres, portes et fermetures - Calcul du coefficient de
transmission thermique - Partie 2: Méthode numérique pour les encadrements -
Amendement 1 (ISO 10077-2:2017/Amd1:2024)
Ta slovenski standard je istoveten z: EN ISO 10077-2:2017/A1:2025
ICS:
91.060.50 Vrata in okna Doors and windows
91.120.10 Toplotna izolacija stavb Thermal insulation of
buildings
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 10077-2:2017/A1
EUROPEAN STANDARD
NORME EUROPÉENNE
January 2025
EUROPÄISCHE NORM
ICS 91.060.50; 91.120.10
English Version
Thermal performance of windows, doors and shutters -
Calculation of thermal transmittance - Part 2: Numerical
method for frames - Amendment 1 (ISO 10077-
2:2017/Amd1:2024)
Performance thermique des fenêtres, portes et Wärmetechnisches Verhalten von Fenstern, Türen und
fermetures - Calcul du coefficient de transmission Abschlüssen - Berechnung des
thermique - Partie 2: Méthode numérique pour les Wärmedurchgangskoeffizienten - Teil 2: Numerisches
encadrements - Amendement 1 (ISO 10077- Verfahren für Rahmen - Änderung 1 (ISO 10077
2:2017/Amd1:2024) 2:2017/Amd 1:2024)
This amendment A1 modifies the European Standard EN ISO 10077-2:2017; it was approved by CEN on 8 November 2024.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for inclusion of
this amendment into the relevant 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 amendment 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, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2025 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 10077-2:2017/A1:2025 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 10077-2:2017/A1:2025) 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 July 2025, and conflicting national standards shall be
withdrawn at the latest by July 2025.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. A complete listing of these bodies can be found on the CEN website.
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, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the
United Kingdom.
Endorsement notice
The text of ISO 10077-2:2017/Amd 1:2024 has been approved by CEN as EN ISO 10077-
2:2017/A1:2025 without any modification.

International
Standard
ISO 10077-2
Third edition
Thermal performance of windows,
2017-06
doors and shutters — Calculation of
thermal transmittance —
AMENDMENT 1
2024-12
Part 2:
Numerical method for frames
AMENDMENT 1
Performance thermique des fenêtres, portes et fermetures —
Calcul du coefficient de transmission thermique —
Partie 2: Méthode numérique pour les encadrements
AMENDEMENT 1
Reference number
ISO 10077-2:2017/Amd.1:2024(en) © ISO 2024

ISO 10077-2:2017/Amd.1:2024(en)
© ISO 2024
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
ISO 10077-2:2017/Amd.1:2024(en)
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.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document 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).
A list of all parts in the ISO 10077 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

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ISO 10077-2:2017/Amd.1:2024(en)
Thermal performance of wi
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