EN ISO 11855-2:2021/A1:2023

SLOVENSKI STANDARD
01-februar-2024
Načrtovanje notranjega okolja v stavbah - Vgrajeni sevalni sistemi ogrevanja in
hladilni sistemi - 2. del: Določanje načrtovane grelne in hladilne moči - Dopolnilo
A1 (ISO 11855-2:2021/Amd 1:2023)
Building environment design - Embedded radiant heating and cooling systems - Part 2:
Determination of the design heating and cooling capacity - Amendment 1 (ISO 11855-
2:2021/Amd 1:2023)
Umweltgerechte Gebäudeplanung - Flächenintegrierte Strahlungsheiz- und -
kühlsysteme - Teil 2: Bestimmung der Auslegungs-Heiz- und Kühlleistung (ISO 11855-
2:2021/Amd 1:2023)
Conception de l'environnement des bâtiments - Systèmes intégrés de chauffage et de
refroidissement par rayonnement - Partie 2: Détermination de la puissance calorifique et
frigorifique à la conception - Amendement 1 (ISO 11855-2:2021/Amd 1:2023)
Ta slovenski standard je istoveten z: EN ISO 11855-2:2021/A1:2023
ICS:
91.140.10 Sistemi centralnega Central heating systems
ogrevanja
91.140.30 Prezračevalni in klimatski Ventilation and air-
sistemi conditioning systems
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 11855-2:2021/A1
EUROPEAN STANDARD
NORME EUROPÉENNE
November 2023
EUROPÄISCHE NORM
ICS 91.040.01
English Version
Building environment design - Embedded radiant heating
and cooling systems - Part 2: Determination of the design
heating and cooling capacity - Amendment 1 (ISO 11855-
2:2021/Amd 1:2023)
Conception de l'environnement des bâtiments - Umweltgerechte Gebäudeplanung - Flächenintegrierte
Systèmes intégrés de chauffage et de refroidissement Strahlungsheiz- und -kühlsysteme - Teil 2: Bestimmung
par rayonnement - Partie 2: Détermination de la der Auslegungs-Heiz- und Kühlleistung (ISO 11855-
puissance calorifique et frigorifique à la conception - 2:2021/Amd 1:2023)
Amendement 1 (ISO 11855-2:2021/Amd 1:2023)
This amendment A1 modifies the European Standard EN ISO 11855-2:2021; it was approved by CEN on 14 May 2023.

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
© 2023 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 11855-2:2021/A1:2023 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 11855-2:2021/A1:2023) has been prepared by Technical Committee ISO/TC
205 "Building environment design" in collaboration with Technical Committee CEN/TC 228 “Heating
systems and water based cooling systems in buildings” the secretariat of which is held by DIN.
This Amendment to the European Standard EN ISO 11855-2:2021 shall be given the status of a national
standard, either by publication of an identical text or by endorsement, at the latest by May 2024, and
conflicting national standards shall be withdrawn at the latest by May 2024.
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 11855-2:2021/Amd 1:2023 has been approved by CEN as EN ISO 11855-
2:2021/A1:2023 without any modification.

INTERNATIONAL ISO
STANDARD 11855-2
Second edition
2021-09
AMENDMENT 1
2023-11
Building environment design —
Embedded radiant heating and cooling
systems —
Part 2:
Determination of the design heating
and cooling capacity
AMENDMENT 1
Conception de l'environnement des bâtiments — Systèmes intégrés de
chauffage et de refroidissement par rayonnement —
Partie 2: Détermination de la puissance calorifique et frigorifique à la
conception
AMENDEMENT 1
Reference number
ISO 11855-2:2021/Amd.1:2023(E)
ISO 11855-2:2021/Amd.1:2023(E)
© ISO 2023
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: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
ISO 11855-2:2021/Amd.1:2023(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.
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 205, Building environment design, in
collaboration with the European Committee for Standardization (CEN) Technical Committee CEN/
TC 228, Heating systems and water based cooling systems in buildings, in accordance with the Agreement
on technical cooperation between ISO and CEN (Vienna Agreement).
A list of all parts in the ISO 11855 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.
iii
ISO 11855-2:2021/Amd.1:2023(E)
Building environment design — Embedded radiant heating
and cooling systems —
Part 2:
Determination of the design heating and cooling capacity
AMENDMENT 1
Clause 4, Table 1
Modify the following rows:
Table 1 — Symbols
Symbol Unit Quantity
s m In system type II, thickness of thermal insulation from the outward edge of the
h
insulation to the inward edge of the pipes (see Figure 2)
s m In system type II, thickness of thermal insulation from the outward edge of the
l
insulation to the outward edge of the pipes (see Figure 2)
S m Thickness of the screed (excluding the pipes in system type I)

Clause 7, second paragraph
Modify to the following:
A given system construction can only be calculated with one of the simplified methods. The correct
method to apply depends on the system type I to IV (position of pipes, concrete or wooden construction)
and the boundary conditions listed in Table 2.
Delete the NOTE.
Table 2
Modify to the following:
Table 2 — Criteria for selection of simplified calculation method
New Old
Reference to
Pipe position system system Figure Boundary conditions
method
type type
In screed I A, C, H, 2 a) W ≥ 0,050 m s ≥ 0,01 m 7.1
u
I, J
Thermally decoupled from the struc- 0,008 m ≤ d ≤ 0,03 m A.2.2
tural base of the building by thermal
s /λ ≥ 0,01
u e
insulation
In insulation, conductive devices II B 2 b) 0,05 m ≤ W ≤ 0,45 m 7.1
Not wooden constructions except 0,014 m ≤ d ≤ 0,022 m A.2.3
for weight bearing and thermal dif-
0,01 m ≤ s /λ ≤ 0,18 m
u e
fusion layer
ISO 11855-2:2021/Amd.1:2023(E)
TTabablele 2 2 ((ccoonnttiinnueuedd))
New Old
Reference to
Pipe position system system Figure Boundary conditions
method
type type
In concrete slab V E 4 S /W ≥ 0,3 7.2,
T
B.1
Capillary tubes in concrete surface III F 5 d /W ≤ 0,2 7.2, B.2
a
Wooden constructions, pipes in sub IV G 6 λ ≥ 10 λ 7.2, Annex C
wl
floor or under sub floor, conductive
S ≥ 0,01
WLλ
devices
7.1, second and third paragraphs
Delete the following:
This calculation method is given in Annex A for the following four types of systems:
— type A with pipes embedded in the screed or concrete (see Figure 2 and A.2.2);
— type B with pipes embedded outside the screed (see Figure 2 and A.2.3);
— type C with pipes embedded in the screed (see Figure 2 and A.2.2);
— type D plane section systems (see A.2.4).
Figure 2 shows the types as embedded in the floor, but the methods can also be applied for wall and
ceiling systems with a corresponding position of the pipes.
Replace with the following:
This calculation method is given in Annex A for the following five types of system:
— type I: pipes directly included in a thermal diffusion layer (see Figure 2);
— type II: pipes included in thermal insulation layer with additional thermal conduction layer (see
Figure 3);
— type III: capillary tubes directly included in a thermal diffusion layer (see Figure 4);
— type IV: pipes with a thermal reflection layer and an air gap to floor covering (see Figure 5);
— type V: pipes included directly in the structural construction (TABS) (see Figure 6).
Figure 3 shows the types as embedded in the floor, but the methods can also be applied for wall and
ceiling systems with a corresponding position of the pipes.

7.1, Figure 2 a)
Replace Figure 2 a) with the new Figure 2.
ISO 11855-2:2021/Amd.1:2023(E)
Key
D external diameter of the pipe
ln thermal insulation layer
Pe pipes or electric cables
Pt protection layer
Sf surface layer
St structural layer
s thickness of the layer above the pipe
u
Td thermal diffusion layer
W pipe spacing
Figure 2 — Radiant system type I: pipes directly included in a thermal diffusion layer

7.1, Figure 2 b)
Replace Figure 2 b) with the new Figure 3.
ISO 11855-2:2021/Amd.1:2023(E)
Key
ln thermal insulation layer
Pe pipes or electric cables
Pt protection layer
Sf surface layer
St structural layer
s thickness of the layer above the pipe
u
s thickness of heat conducting device
wl
Tc thermal conduction layer
Td thermal diffusion layer
W pipe spacing
Figure 3 — Radiant system type II: pipes included in a thermal insulation layer with additional
thermal conduction layer
7.1, Figure 2 c)
Replace Figure 2 c) with the new Figure 4.
...