oSIST prEN 17956:2023

SLOVENSKI STANDARD
oSIST prEN 17956:2023
01-maj-2023
Sistemi za ogrevanje in hlajenje z vodo v stavbah - Razredi energijske
učinkovitosti za tehnične izolacijske sisteme - Računska metoda in uporaba
Heating systems and water based cooling systems in buildings - Energy efficiency
classes for technical insulation systems - Calculation method and applications
Heizungsanlagen und wassergeführte Kühlanlagen in Gebäuden -
Energieeffizienzklassen für technische Dämmsysteme - Berechnungsmethoden
Systèmes de chauffage et systèmes de refroidissement hydrauliques dans les bâtiments
- Classes d’efficacité énergétique pour les systèmes d’isolation technique - Méthodes et
applications de calcul
Ta slovenski standard je istoveten z: prEN 17956
ICS:
91.120.10 Toplotna izolacija stavb Thermal insulation of
buildings
91.140.10 Sistemi centralnega Central heating systems
ogrevanja
91.140.30 Prezračevalni in klimatski Ventilation and air-
sistemi conditioning systems
oSIST prEN 17956:2023 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN 17956:2023


DRAFT
EUROPEAN STANDARD
prEN 17956
NORME EUROPÉENNE

EUROPÄISCHE NORM

February 2023
ICS 91.140.10; 91.140.30; 91.120.10
English Version

Heating systems and water based cooling systems in
buildings - Energy efficiency classes for technical
insulation systems - Calculation method and applications
 Heizungsanlagen und wassergeführte Kühlanlagen in
Gebäuden - Energieeffizienzklassen für technische
Dämmsysteme - Berechnungsmethoden
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee
CEN/TC 228.

If this draft becomes a European Standard, 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.

This draft European Standard was established by CEN 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.

Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.

Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a European Standard.


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. prEN 17956:2023 E
worldwide for CEN national Members.

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Contents Page
European foreword . 3
Introduction . 4
1 Scope . 5
2 Normative references . 5
3 Terms and definitions, symbols, units and abbreviated terms . 5
3.1 Terms and definitions . 5
3.2 Symbols, units and abbreviated terms . 6
3.2.1 Symbols and units used in this document (according to ISO) . 6
3.2.2 Abbreviated terms used in this document . 7
4 Calculation method for energy efficiency classes. 7
4.1 General . 7
4.2 Determination of the maximum allowed density of heat flow rate . 7
5 Application of energy efficiency classes . 10
5.1 General . 10
5.2 Selection of the energy efficiency performance of the insulation system . 10
5.3 Designing phase of the operational installation . 11
5.4 Dimensioning of the insulation system . 11
5.4.1 General . 11
5.4.2 Verification process for insulation systems . 11
5.4.3 Verification process for built-in components (valves, flanges, etc.) . 11
Annex A (informative) Example calculation – How to estimate the indicative space requirement
for an insulation system for a selected energy efficiency class . 13
Annex B (informative) Example calculation –Dimensioning of a specified energy efficiency
class insulation system for pipes . 16
Annex C (informative) Example calculation – Dimensioning of a specified energy efficiency
class insulation system for built-in components . 18
Annex D (informative) Tabulated space requirement for insulation per energy efficiency class
........................................................................................................................................................................... 19
Annex E (informative) Tabulated maximum permissible density of heat flow rate per energy
efficiency class . 22
Annex F (informative) Egological optimum . 25
Bibliography . 26

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European foreword
This document (prEN 17956:2023) has been prepared by Technical Committee CEN/TC 228 "Heating
systems and water-based cooling systems in buildings", the secretariat of which is held by DIN.
This document is currently submitted to the CEN Enquiry.
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Introduction
In the past, technical thermal insulation systems have been primarily designed according to operational
requirements, e.g. personal protection or maximum permissible heat loss. Occasionally, the design may
be based on economic aspects, which strongly depend on the assumptions for the service life, energy
costs and initial investment costs.
This document creates a uniform basis with a focus on the efficient use of resources.
For this purpose, a classification method is defined for technical insulation systems. Depending on the
operating temperature of the system to be insulated and its basic geometric shape, these energy
efficiency classes describe a maximum permissible heat flux.
This classification is intended to create a uniform communication platform for all those involved in the
operation as well as the engineering and installation of insulation systems in plant construction and
technical building equipment. The energy classes serve to provide the most basic information about an
insulation system in a simple way, independent of the actually applied insulation system.
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1 Scope
This document covers technical insulation systems of operational installations in industry and the
building services, such as pipes, ducts, vessels, equipment and built-in components.
The document contains methods for the energy efficiency classification of insulation systems for above-
mentioned components with an operational temperature range of -30 °C up to 650 °C.
The document addresses plant operators, engineers of operational installations as well as the involved
contractors such as insulation contractors and pipefitting contractors.
The design of safe surface temperatures for personnel protection is outside the scope of this document.
This document also does not apply to heating, cooling and ventilation systems in buildings and does not
apply to directly buried district heating and district cooling pipes.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
EN ISO 12241, Thermal insulation for building equipment and industrial installations - Calculation rules
(ISO 12241)
3 Terms and definitions, symbols, units and abbreviated terms
For the purposes of this document, the following terms and definitions, symbols, units and abbreviated
terms apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://www.iso.org/obp/
— IEC Electropedia: available at https://www.electropedia.org/
3.1 Terms and definitions
3.1.1
operational installation
stationary technical installation inside or outside of buildings, which is used for and directly supports
the operational purpose
3.1.2
insulation system
insulation material including all other constituent parts, e.g. cladding, vapour barrier, supporting
structure
3.1.3
operating temperature
temperature with which an industrial installation is generally operated
3.1.4
ecological optimum
ecological optimum for an insulation system is dimensioned for minimum total greenhouse gas
emissions over the life cycle (manufacture, use, disposal)
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3.1.5
hot applications
applications where the operating temperature is above 15 °C
3.1.6
cold applications
applications where the operating temperature is below 15 °C
3.1.7
density of heat flow rate
flow of energy per unit of area per unit of time
2
Note 1 to entry: The unit for walls is watts per square metre (W/m ).
3.1.8
longitudinal density of heat flow rate
flow of energy per unit of length per unit of time
Note 1 to entry: The unit for round objects like pipes is watt per metre (W/m).
3.1.9
average conditions
average values, for example for temperature and wind speed, which are needed to calculate the heat
loss of an insulation system throughout the year
3.1.10
indicative space requirement for an insulation system
estimated insulation thickness based on a standard reference insulation material needed to achieve the
selected insulation energy efficiency class
3.2 Symbols, units and abbreviated terms
3.2.1 Symbols and units used in this document (according to ISO)
a width of the rectangular duct section m
b height of the rectangular duct section m
b , b , auxiliary energy efficiency class coefficients –
0 1
b , b
2 3
C energy efficiency class coefficient
e Euler’s number
D external pipe diameter m
G geometry coefficient -
K , K application coefficients –
1 2
q longitudinal density of heat flow rate W/m
l
2
q density of heat flow rate W/m
ISRI Indicative Space Requirement for Insulation system m
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t temperature coefficient –
W material coefficient –
θ operating temperature (interior) °C
i
θ ambient temperature °C
a
The following indices are used throughout this document:
X any of the energy efficiency classes A to F
3.2.2 Abbreviated terms used in this document
EEC energy efficiency class
4 Calculation method for energy efficiency classes
4.1 General
This document establishes, for a given application, the maximum allowed density of heat flow rate of an
insulation system per energy efficiency class. The theoretical background of the calculation method
developed in 4.2 is based on the definition of the ecological optimum extracted from the VDI 4610,
Part 1 and summarized in Annex F of this document.
The calculation method for energy efficiency classes also defines the space that shall be respected and
planned, in the designing phase of the operational installation, to assure enough space for the insulation
system according to the selected energy class. This dimension is defined by the indicative space
requirement for insulation systems, ISRI (Step 4 in Table 1 and Table 2).
X
For a quick indication of the space requirement covering a selected range of pipe/duct sizes and
temperatures, users of this document may refer to Annex D, Tables D.1 and D.2.
4.2 Determination of the maximum allowed density of heat flow rate
The energy efficiency classes go from A to F. Each class is defined by a maximum allowed density of heat
flow rate depending on the operating temperature during the operation of the installation as well as the
geometry of the component.
For an installation with an operating temperature of exactly 15 °C, no energy efficiency class is defined.
Table 1 and Table 2 define the workflow to obtain the maximum allowed density of heat flow rate of an
insulation system for the selected energy efficiency class:
Table 1 is to be used for hot applications.
Table 2 is to be used for cold applications.
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Table 1 — Calculation steps to determine the maximum allowed density of heat flow
rate for the selected insulation energy efficiency class for hot applications
a
Pipes and round Rectangular ducts Walls
geometries with (Figure 1) with

Step 1:
22⋅ab+⋅
D
D=
Determine the
π
geometry coefficient,
GD=

G=1,22
G
m
If G > 1,22 m then G = 1,22 m
Hot applications: 15 °CC<θ ≤650 °
i
Step2: θ+15
i
t=
Calculate the
2
in °C
application
−−5 7 2 −10 3
W 0,0477+ 9,548⋅10⋅+t 1,516⋅10⋅t+ 3,723⋅10⋅t
coefficients,
K K
1, 2
0,14⋅⋅W θ−15
i
0,19
K =
K =
1
2 2
G G

bK⋅ b+⋅bK
12 2 3 2
C 0,96+⋅b e⋅K
Step 3:
X 01

Calculate the Energy
where
Efficiency Class
b b b b are the auxiliary coefficients of the selected ECC X,
0, 1, 2, 3
(EEC) coefficient, CX
from Table 3, e is Euler’s number, equals to 2,71828
Step 4:
Calculate the
G
Indicative Space
ISRI=⋅−(C 1)
X X
Requirement for 2
in m
Insulation systems,
ISRI
X
Pipes, round geometries,
Step 5:
rectangular ducts
Walls
Calculate the maximum
2⋅⋅πθW⋅ −15
W⋅−θ 15
i
i
allowed density of heat flow
q =
q =
l,X
X
rate for the selected energy
2⋅ISRI
  ISRI
X
X

ln 1+
 
efficiency class X,
D 2
 
in W/m
in
q or q
l,X X
W/m
a
Note that this document uses the concept of hydraulic diameter – a commonly used term when
handling flow in non-circular tubes. The hydraulic diameter evaluates non-circular ducts as ducts of
equivalent circular diameter.
8
=
=

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Table 2 — Calculation steps to determine the maximum allowed density of heat flow
rate for the selected insulation energy efficiency class for cold applications
a
Pipes and round Rectangular ducts Walls
geometries with (Figure 1) with

Step 1:
22⋅ab+⋅
D

D=
Determine the
π
geometry coefficient,
GD=

G=1,22
G
m
If G > 1,22 m then G = 1,22 m
Cold applications: −30°CC≤θ <15 °
i
Step2: θ+15
i
t=
Calculate the
2
in °C
application
−−4 8 2 −10 3
W 0,035 5+1,17⋅10⋅+t 4,85⋅10⋅t+ 5,58⋅10⋅t
coefficients,

K1, K2
0,06⋅⋅W θ−15
i
0,1
K =
K =
1
2 2
G G

bK⋅ b+⋅bK
12 2 3 2
C 0,96+⋅b e⋅K
Step 3:
X 01

Calculate the Energy
where
Efficiency Class
b b b b are the auxiliary coefficients of the selected ECC X,
0, 1, 2, 3
(EEC) coefficient, C
X
from Table 3, e is Euler’s number, equals to 2,71828
Step 4:
Calculate the
G
Indicative Space
ISRI=⋅−C 1
( )
X X
Requirement for 2
in m
Insulation systems,
ISRI
X
Pipes, round geometries,
Step 5:
rectangular ducts
Walls
Calculate the maximum
2⋅⋅πθW⋅ −15
W⋅−θ 15
i
allowed density of heat flow i
q =
q =
l,X
X
rate for the selected energy 2⋅ISRI
 
ISRI
X
X

ln 1+
 
efficiency class X,
D 2
 
in W/m
in
q or q
l,X X
W/m
a
Note that this document uses the concept of hydraulic diameter – a commonly used term when
handling flow in non-circular tubes. The hydraulic diameter evaluates non-circular ducts as ducts of

equivalent circular diameter.
Table 3 gives the auxiliary EEC coefficients for the selected energy efficiency class X to be used in Table 1
and Table 2, Step 3.
9
=
=

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Table 3 — Auxiliary EEC coefficients
Energy efficiency
b b b b
0 1 2 3
class (EEC)
A 0,7320 –0,1475 0,3573 0,0126
B 0,6052 –0,1362 0,3429 0,0102
C 0,5006 –0,1224 0,3278 0,0076
D 0,4037 –0,1059 0,3106 0,0047
E 0,3255 –0,0904 0,2937 0,0023
F 0,2608 –0,0769 0,2769 0,0003
For a quick indication of the maximum allowed density of heat flow rate, covering a selected range of
pipe/duct sizes and temperatures, users of this document may refer to Annex E, Tables E.1 and E.2.

Key
1 transverse joints
2 longitudinal seam
Figure 1 — Dimensions of a rectangular duct
5 Application of energy efficiency classes
5.1 General
The insulation energy efficiency classification is intended to inform asset owners about the level of
energy conservation in their processes. Once the energy efficiency class is selected, it also simplifies the
workflow from the general planning of the operational installation to the execution of the insulation
work. The architect or plan engineer shall ensure that the spatial conditions allow for the selected
energy efficiency class which can then be implemented (and even improved) using appropriate
insulation systems for pipes, ducts, equipment and built-in components. The insulation contractor is
responsible for the dimensioning and the proper execution of the insulation.
5.2 Selection of the energy efficiency performance of the insulation system
The asset owner or operator defines the l
...