SIST EN ISO 11855-2:2015

Building environment design - Design, dimensioning, installation and control of embedded radiant heating and cooling systems - Part 2: Determination of the design heating and cooling capacity (ISO 11855-2:2012)

This European Standard is applicable to water based surface heating and cooling systems in residential, commercial and industrial buildings.
The methods apply to systems integrated into the wall, floor or ceiling construction without any open air gaps.
The methods do not apply to heated or chilled ceiling panels or beams.
This standard provides steady-state calculation methods for determination of the heating and cooling capacity (part 2).
This standard applies also, as appropriate, to the use of other fluids instead of water.
This standard is not applicable for testing of systems.

Umweltgerechte Gebäudeplanung - Planung, Auslegung, Installation und Steuerung flächenintegrierter Strahlheizungs- und -kühlsysteme - Teil 2: Bestimmung der Auslegungs-Heiz- bzw. Kühlleistung (ISO 11855-2:2012)012)

Conception de l'environnement des bâtiments - Conception, dimensionnement, installation et contrôle des systèmes intégrés de chauffage et de refroidissement par rayonnement - Partie 2 : Détermination de la puissance calorifique et frigorifique à la conception (ISO 11855-2:2012)

Okoljsko primerna zasnova stavb - Zasnova, dimenzioniranje, vgradnja in kontrola vgrajenih sevalnih ogrevalnih in hladilnih sistemov - 2. del: Določanje načrtovane grelne in hladilne moči (ISO 11855-2:2012)

Ta evropski standard se uporablja za ploskovne sisteme za ogrevanje in hlajenje z vodo v stanovanjskih, poslovnih ter industrijskih stavbah. Metode se uporabljajo za sisteme, vgrajene v stensko, talno ali stropno konstrukcijo brez odprtih vmesnih zračnih prostorov. Metode se ne uporabljajo za ogrevane ali hlajene stropne plošče ali tramove. Ta standard določa ustaljene metode računanja za določanje grelne in hladilne moči (2. del). Ta standard, kadar je to ustrezno, velja tudi za uporabo drugih tekočin namesto vode. Ta standard se ne uporablja za preskušanje sistemov.

General Information

• Status: Withdrawn
• Public Enquiry End Date: 09-Jul-2015
• Publication Date: 09-Sep-2015
• Withdrawal Date: 14-Oct-2021
• ICS: 91.140.10 - Central heating systems
• ICS: 91.140.30 - Ventilation and air-conditioning systems
• Technical Committee: OGS - Heating for buildings
• Current Stage: 9900 - Withdrawal (Adopted Project)
• Start Date: 15-Oct-2021
• Due Date: 07-Nov-2021
• Completion Date: 15-Oct-2021
• Ref Project: EN ISO 11855-2:2015 - Building environment design - Design, dimensioning, installation and control of embedded radiant heating and cooling systems - Part 2: Determination of the design heating and cooling capacity (ISO 11855-2:2012)

Relations

• Replaced By: SIST EN ISO 11855-2:2021 - Building environment design - Embedded radiant heating and cooling systems - Part 2: Determination of the design heating and cooling capacity (ISO 11855-2:2021)
• Effective Date: 13-Oct-2021
• Replaced By: SIST EN ISO 11855-2:2021 - Building environment design - Embedded radiant heating and cooling systems - Part 2: Determination of the design heating and cooling capacity (ISO 11855-2:2021)
• Effective Date: 08-Jun-2022
• Revised: SIST EN ISO 11855-2:2021 - Building environment design - Embedded radiant heating and cooling systems - Part 2: Determination of the design heating and cooling capacity (ISO 11855-2:2021)
• Effective Date: 01-May-2020
• Replaces: SIST EN 15377-1:2008 - Heating systems in buildings - Design of embedded water based surface heating and cooling systems - Part 1: Determination of the design heating and cooling capacity
• Effective Date: 01-Oct-2015
• Replaces: SIST EN 15377-1:2008 - Heating systems in buildings - Design of embedded water based surface heating and cooling systems - Part 1: Determination of the design heating and cooling capacity
• Effective Date: 08-Jun-2022

Standards Content (Sample)

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Umweltgerechte Gebäudeplanung - Planung, Auslegung, Installation und Steuerung flächenintegrierter Strahlheizungs- und -kühlsysteme - Teil 2: Bestimmung der Auslegungs-Heiz- bzw. Kühlleistung (ISO 11855-2:2012)012)Conception de l'environnement des bâtiments - Conception, dimensionnement, installation et contrôle des systèmes intégrés de chauffage et de refroidissement par rayonnement - Partie 2 : Détermination de la puissance calorifique et frigorifique à la conception (ISO 11855-2:2012)Building environment design - Design, dimensioning, installation and control of embedded radiant heating and cooling systems - Part 2: Determination of the design heating and cooling capacity (ISO 11855-2:2012)91.140.30VLVWHPLVentilation and air-conditioning91.140.10Sistemi centralnega ogrevanjaCentral heating systemsICS:Ta slovenski standard je istoveten z:EN ISO 11855-2:2015SIST EN ISO 11855-2:2015en,fr,de01-oktober-2015SIST EN ISO 11855-2:2015SLOVENSKI
STANDARD



SIST EN ISO 11855-2:2015



EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 11855-2
August 2015 ICS 91.140.10; 91.140.30 English Version
Building environment design - Design, dimensioning, installation and control of embedded radiant heating and cooling systems - Part 2: Determination of the design heating and cooling capacity (ISO 11855-2:2012)
Conception de l'environnement des bâtiments - Conception, dimensionnement, installation et contrôle des systèmes intégrés de chauffage et de refroidissement par rayonnement - Partie 2 : Détermination de la puissance calorifique et frigorifique à la conception (ISO 11855-2:2012)
Umweltgerechte Gebäudeplanung - Planung, Auslegung, Installation und Steuerung flächenintegrierter Strahlheizungs- und -kühlsysteme - Teil 2: Bestimmung der Auslegungs-Heiz- bzw. Kühlleistung (ISO 11855-2:2012)012) This European Standard was approved by CEN on 30 July 2015.
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, Former Yugoslav Republic of Macedonia, 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
CEN-CENELEC Management Centre:
Avenue Marnix 17,
B-1000 Brussels © 2015 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 11855-2:2015 ESIST EN ISO 11855-2:2015



EN ISO 11855-2:2015 (E) 2 Contents Page European foreword .3 SIST EN ISO 11855-2:2015



EN ISO 11855-2:2015 (E) 3 European foreword The text of ISO 11855-2:2012 has been prepared by Technical Committee ISO/TC 205 “Building environment design” of the International Organization for Standardization (ISO) and has been taken over as EN ISO 11855-2:2015 by Technical Committee CEN/TC 228 “Heating systems and water based cooling systems in buildings” the secretariat of which is held by DIN. 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 February 2016, and conflicting national standards shall be withdrawn at the latest by February 2016. This standard is applicable for design, construction and operation of radiant heating and cooling systems. The methods defined in part 2 are intended to determine the design heating or cooling capacity used for the design and evaluation of the performance of the system. For identifying product characteristics by testing and proving the thermal output of heating and cooling surfaces embedded in floors, ceilings and walls the standard series EN 1264 can be used.
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. 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, Former Yugoslav Republic of Macedonia, 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 11855-2:2012 has been approved by CEN as EN ISO 11855-2:2015 without any modification. SIST EN ISO 11855-2:2015



SIST EN ISO 11855-2:2015



Reference numberISO 11855-2:2012(E)© ISO 2012
INTERNATIONAL STANDARD ISO11855-2First edition2012-10-01Building environment design — Design, dimensioning, installation and control of embedded radiant heating and cooling systems — Part 2: Determination of the design heating and cooling capacity Conception de l'environnement des bâtiments — Conception, construction et fonctionnement des systèmes de chauffage et de refroidissement par rayonnement — Partie 2: Détermination de la puissance calorifique et frigorifique à la conception
SIST EN ISO 11855-2:2015



ISO 11855-2:2012(E)
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ISO 2012 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.
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© ISO 2012 – All rights reserved
SIST EN ISO 11855-2:2015



ISO 11855-2:2012(E) © ISO 2012 – All rights reserved
iii Contents Page Foreword . iv Introduction . v 1 Scope . 1 2 Normative references . 1 3 Terms and definitions . 2 4 Symbols and abbreviations . 2 5 Concept of the method to determine the heating and cooling capacity . 3 6 Heat exchange coefficient between surface and space . 4 7 Simplified calculation methods for determining heating and cooling capacity or surface temperature . 6 7.1 Universal single power function . 7 7.2 Thermal resistance methods . 9 8 Use of basic calculation programs . 11 8.1 Basic calculation programs . 11 8.2 Items to be included in a complete computation documentation . 11 9 Calculation of the heating and cooling capacity . 12 Annex A (normative)
Calculation of the heat flux . 13 Annex B (normative)
General resistance method . 36 Annex C (normative)
Pipes embedded in wooden construction . 42 Annex D (normative)
Method for verification of FEM and FDM calculation programs . 50 Annex E (normative)
Values for heat conductivity of materials and air layers . 54 Bibliography . 56
SIST EN ISO 11855-2:2015



ISO 11855-2:2012(E) iv
© ISO 2012 – All rights reserved 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 11855-2 was prepared by Technical Committee ISO/TC 205, Building environment design. ISO 11855 consists of the following parts, under the general title Building environment design — Design, dimensioning, installation and control of embedded radiant heating and cooling systems:  Part 1: Definition, symbols, and comfort criteria  Part 2: Determination of the design and heating and cooling capacity  Part 3: Design and dimensioning  Part 4: Dimensioning and calculation of the dynamic heating and cooling capacity of Thermo Active Building Systems (TABS)  Part 5: Installation  Part 6: Control Part 1 specifies the comfort criteria which should be considered in designing embedded radiant heating and cooling systems, since the main objective of the radiant heating and cooling system is to satisfy thermal comfort of the occupants. Part 2 provides steady-state calculation methods for determination of the heating and cooling capacity. Part 3 specifies design and dimensioning methods of radiant heating and cooling systems to ensure the heating and cooling capacity. Part 4 provides a dimensioning and calculation method to design Thermo Active Building Systems (TABS) for energy-saving purposes, since radiant heating and cooling systems can reduce energy consumption and heat source size by using renewable energy. Part 5 addresses the installation process for the system to operate as intended. Part 6 shows a proper control method of the radiant heating and cooling systems to ensure the maximum performance which was intended in the design stage when the system is actually being operated in a building. SIST EN ISO 11855-2:2015



ISO 11855-2:2012(E) © ISO 2012 – All rights reserved
v Introduction The radiant heating and cooling system consists of heat emitting/absorbing, heat supply, distribution, and control systems. The ISO 11855 series deals with the embedded surface heating and cooling system that directly controls heat exchange within the space. It does not include the system equipment itself, such as heat source, distribution system and controller.
The ISO 11855 series addresses an embedded system that is integrated with the building structure. Therefore, the panel system with open air gap, which is not integrated with the building structure, is not covered by this series.
The ISO 11855 series shall be applied to systems using not only water but also other fluids or electricity as a heating or cooling medium.
The object of the ISO 11855 series is to provide criteria to effectively design embedded systems. To do this, it presents comfort criteria for the space served by embedded systems, heat output calculation, dimensioning, dynamic analysis, installation, operation, and control method of embedded systems. SIST EN ISO 11855-2:2015



SIST EN ISO 11855-2:2015



INTERNATIONAL STANDARD ISO 11855-2:2012(E) © ISO 2012 – All rights reserved 1 Building environment design — Design, dimensioning, installation and control of embedded radiant heating and cooling systems — Part 2: Determination of the design heating and cooling capacity 1 Scope This part of ISO 11855 specifies procedures and conditions to enable the heat flow in water based surface heating and cooling systems to be determined relative to the medium differential temperature for systems. The determination of thermal performance of water based surface heating and cooling systems and their conformity to this part of ISO 11855 is carried out by calculation in accordance with design documents and a model. This should enable a uniform assessment and calculation of water based surface heating and cooling systems. The surface temperature and the temperature uniformity of the heated/cooled surface, nominal heat flow density between water and space, the associated nominal medium differential temperature, and the field of characteristic curves for the relationship between heat flow density and the determining variables are given as the result. This part of ISO 11855 includes a general method based on Finite Difference or Finite Element Methods and simplified calculation methods depending on position of pipes and type of building structure. The ISO 11855 series is applicable to water based embedded surface heating and cooling systems in residential, commercial and industrial buildings. The methods apply to systems integrated into the wall, floor or ceiling construction without any open air gaps. It does not apply to panel systems with open air gaps which are not integrated into the building structure.
The ISO 11855 series also applies, as appropriate, to the use of fluids other than water as a heating or cooling medium. The ISO 11855 series is not applicable for testing of systems. The methods do not apply to heated or chilled ceiling panels or beams. 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 11855-1:2012, Building environment design — Design, dimensioning, installation and control of embedded radiant heating and cooling systems — Part 1: Definition, symbols, and comfort criteria EN 1264-2, Water based surface embedded heating and cooling systems — Part 2: Floor heating: Prove methods for the determination of the thermal output using calculation and test methods SIST EN ISO 11855-2:2015



ISO 11855-2:2012(E) 2
© ISO 2012 – All rights reserved 3 Terms and definitions For the purposes of this document, the terms and definitions given in ISO 11855-1:2012 apply. 4 Symbols and abbreviations For the purposes of this document, the symbols and abbreviations in Table 1 apply. Table 1 — Symbols and abbreviations Symbol Unit Quantity i — Parameter factors for calculation of characteristic curves
AA m2 Surface of the occupied area
AF m2 Surface of the heating/cooling surface area
AR m2 Surface of the peripheral area
bu — Calculation factor depending on the pipe spacing
B, BG, B0 W/(m2K) Coefficients depending on the system
D m External diameter of the pipe, including sheathing where used
da m External diameter of the pipe di m Internal diameter of the pipe dM m External diameter of sheathing
cW kJ/(kgK) Specific heat capacity of water
ht W/(m2K) Total heat exchange coefficient (convection + radiation) between surface and space
KH W/(m2K) Equivalent heat transmission coefficient
KWL — Parameter for heat conducting devices
kfin — Parameter for heat conducting devices
kCL — Parameter for heat conducting layer
LWL m Width of heat conducting devices
Lfin m Width of fin (horizontal part of heat conducting device seen as a heating fin)
LR m Length of installed pipes
m — Exponents for determination of characteristic curves
mH kg/s Design heating/cooling medium flow rate
n, nG — Exponents
q W/m2 Heat flux at the surface
qA W/m2 Heat flux in the occupied area
qdes W/m2 Design heat flux
qG W/m2 Limit heat flux qN W/m2 Nominal heat flux qR W/m2 Heat flux in the peripheral area
qu W/m2 Outward heat flux Ro m2K/W Partial inwards heat transmission resistance of surface structure
Ru m2K/W Partial outwards heat transmission resistance of surface structure
R,B m2K/W Thermal resistance of surface covering
SIST EN ISO 11855-2:2015



ISO 11855-2:2012(E) © ISO 2012 – All rights reserved 3 R,ins m2K/W Thermal resistance of thermal insulation
sh m In Type B systems, thickness of thermal insulation from the outward edge of the insulation to the inward edge of the pipes (see Figure 2)
sl m In Type B systems, thickness of thermal insulation from the outward edge of the insulation to the outward edge of the pipes (see Figure 2)
sins m Thickness of thermal insulation sR m Pipe wall thickness su m Thickness of the layer above the pipe sWL m Thickness of heat conducting device S m Thickness of the screed (excluding the pipes in type A systems)
W m Pipe spacing
 W/(m2K) Heat exchange coefficient
s,max °C Maximum surface temperature
s,min °C Minimum surface temperature
i °C Design indoor temperature
m °C Temperature of the heating/cooling medium
R °C Return temperature of heating/cooling medium
V °C Supply temperature of heating/cooling medium
u °C Indoor temperature in an adjacent space
H K Heating/cooling medium differential temperature
H,des K Design heating/cooling medium differential temperature
H,G K Limit of heating/cooling medium differential temperature
N K Nominal heating/cooling medium differential temperature
V K Heating/cooling medium differential supply temperature
V,des K Design heating/cooling medium differential supply temperature
 W/(mK) Thermal conductivity
 K Temperature drop V R  — Conversion factor for temperatures
 — Content by volume of the attachment burrs in the screed
5 Concept of the method to determine the heating and cooling capacity A given type of surface (floor, wall, ceiling) delivers, at a given average surface temperature and indoor temperature (operative temperature i), the same heat flux in any space independent of the type of embedded system. It is therefore possible to establish a basic formula or characteristic curve for cooling and a basic formula or characteristic curve for heating, for each of the type of surfaces (floor, wall, ceiling), independent of the type of embedded system, which is applicable to all heating and cooling surfaces (see Clause 6). Two methods are included in this part of ISO 11855:  simplified calculation methods depending on the type of system (see Clause 7);  Finite Element Method and Finite Difference Method (see Clause 8). SIST EN ISO 11855-2:2015



ISO 11855-2:2012(E) 4
© ISO 2012 – All rights reserved Different simplified calculation methods are included in Clause 7 for calculation of the surface temperature (average, maximum and minimum temperature) depending on the system construction (type of pipe, pipe diameter, pipe distance, mounting of pipe, heat conducting devices, distribution layer) and construction of the floor/wall/ceiling (covering, insulation layer, trapped air layer, etc.). The simplified calculation methods are specific for the given type of system, and the boundary conditions listed in Clause 7 shall be met. In the calculation report, it shall be clearly stated which calculation method has been applied. In case a simplified calculation method is not available for a given type of system, either a basic calculation using two or three dimensional finite element or finite difference method can be applied (see Clause 8 and Annex D). NOTE In addition, laboratory testing (for example EN 1264-2:2008, Clause 9) may be applied. Based on the calculated average surface temperature at given combinations of medium (water) temperature and space temperature, it is possible to determine the steady state heating and cooling capacity (see Clause 9). 6 Heat exchange coefficient between surface and space The relationship between the heat flux and mean differential surface temperature [see Figure 1 and Equations (1) to (4)] depends on the type of surface (floor, wall, ceiling) and whether the temperature of the surface is lower (cooling) or higher (heating) than the space temperature.
Figure 1 — Basic characteristic curve for floor heating and ceiling cooling SIST EN ISO 11855-2:2015



ISO 11855-2:2012(E) © ISO 2012 – All rights reserved 5 For floor heating and ceiling cooling in Figure 1, the heat flow density q is given by: q = 8,92 (S,m i)1,1 (W/m2) (1) where S,m is the average surface temperature in°C; i is the nominal indoor operative temperature in °C. For other types of surface heating and cooling systems, the heat flux q is given by: Wall heating and wall cooling: q = 8 (|s,m i |) (W/m2)
(2) Ceiling heating: q = 6 (|s,m i |) (W/m2)
(3) Floor cooling: q = 7 (|s,m i |) (W/m2)
(4) The heat transfer coefficient is combined convection and radiation. NOTE In many building system simulations using dynamic computer models, the heat transfer is often split up in a convective part (between heated/cooled surface and space air) and a radiant part (between heated/cooled surface and the surrounding surfaces or sources). The radiant heat transfer coefficient may in the normal temperature range 15-30 °C be fixed to 5,5 W/m2K. The convective heat transfer coefficient depends on type of surface, heating or cooling, air velocity (forced convection) or temperature difference between surface and air (natural convection). For using the simplified calculation method in Annex A the characteristic curves present the heat flux as a function of the difference between the heating/cooling medium temperature and the indoor temperature. For the user of Annex A, this means not to do any calculations by directly using values of heat exchange coefficients. Consequently, Annex A does not include values for such an application or special details or equations concerning heat exchange coefficients on heating or cooling surfaces. Thus, the values . of Table A.12 of Annex A are not intended to calculate the heat flux directly. In fact, they are provided exclusively for the conversion of characteristic curves in accordance with Equation (A.32) in Clause A.3. For simplifications these calculations are based on the same heat exchange coefficient for floor cooling and ceiling heating, 6,5 W/m2K. For every surface heating and cooling system, there is a maximum allowable heat flux, the limit heat flux qG. This is determined for a selected design indoor room temperature of i (for heating, often 20 °C and for cooling, often 26 °C) at the maximum or minimum surface temperature F,max and a temperature drop  = 0 K. For the calculations, the centre of the heating or cooling surface area, regardless of the type of system, is used as a reference point for S,max. The average surface temperature, S,m, which determines the heat flow density (refer to the basic characteristic curve) is linked with the maximum or minimum surface temperature: S,m  S,max and. S,m  S,min always applies. The attainable value, S,m, depends not only on the type of system, but also on the operating conditions (temperature drop  = V R, outward heat flow qu and heat resistance of the covering R,B). The following assumptions form the basis for calculation of the heat flux:  heat transfer between the heated or cooled surface and the space occurs in accordance with the basic characteristic curve; SIST EN ISO 11855-2:2015



ISO 11855-2:2012(E) 6
© ISO 2012 – All rights reserved  the temperature drop  = 0. The dependence of the characteristic curve on the temperature drop is determined by using the logarithmically determined mean differential heating medium temperature H [see Equation (1)];  turbulent flow in pipe: mkgdhm; Hi4000 no lateral heat flow. 7 Simplified calculation methods for determining heating and cooling capacity or surface temperature Two types of simplified calculation methods can be applied according to this part of ISO 11855:  one method is based on a single power function product of all relevant parameters developed from the finite element method (FEM);  another method is based on calculation of equivalent thermal resistance between the temperature of the heating or cooling medium and the surface temperature (or room temperature). A given system construction can only be calculated with one of the simplified methods. The correct method to apply depends on the type of system, A to G (position of pipes, concrete or wooden construction) and the boundary conditions listed in Table 2. Table 2 — Criteria for selection of simplified calculation method Pipe position Type of system Figure Boundary conditions Reference to method In screed Thermally decoupled from the structural base of the building by thermal insulation A, C 2 a) W  0,050 m su  0,01 m 0,008 m  d  0,03 m su/e  0,01 7.1 A.2.2 In insulation, conductive devices Not wooden constructions except for weight bearing and thermal diffusion layer B 2 b) 0,05 m  W  0,45 m
0,014 m  d  0,022 m 0,01 m  su/e  0,18 7.1 A.2.3 Plane section system
D 2 c)
7.1, A.2.4 In concrete slab
E 4 ST /W  0,3 7.2, B.1 Capillar tubes in concrete surface
F 5 da/W  0,2
7.2, B.2 Wooden constructions, pipes in sub floor or under sub floor, conductive devices G 6 wl  10 surroundingmaterial SWL   0,01
7.2, Annex C
SIST EN ISO 11855-2:2015



ISO 11855-2:2012(E) © ISO 2012 – All rights reserved 7 7.1 Universal single power function The heat flux between embedded pipes (temperature of heating or cooling medium) and the space is calculated by the general equation: imiiqBaH()û (W/m2) (5) where B is a system-dependent coefficient in W/(m2K). This depends on the type of system; ()imiia is the power product, which links the parameters of the structure (surface covering, pipe spacing, pipe diameter and pipe covering). 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. This method shall only be used for system configurations meeting the boundary conditions listed for the different types of systems in Annex A.
a)
Type A and C Key 1 floor covering 2 weight bearing and thermal diffusion layer (cement screed, anhydrite screed, asphalt screed) 3 thermal insulation 4 structural bearing SIST EN ISO 11855-2:2015



ISO 11855-2:2012(E) 8
© ISO 2012 – All rights reserved
b)
Type B Key 1 floor covering 2 weight bearing and thermal diffusion layer (cement screed, anhydrite screed, asphalt screed, wood) 3 heat diffusion devices 4 thermal insulation 5 structural bearing SIST EN ISO 11855-2:2015



ISO 11855-2:2012(E) © ISO 2012 – All rights reserved 9
c)
Type D Key 1 floor covering R, B 2 weight bearing and thermal diffusion layer (cement screed, anhydrite screed, asphalt screed, timber) 3 thermal insulation 4 structural bearing Figure 2 — System types A, B and C covered by the method in Annex A 7.2 Thermal resistance methods The heat flux between embedded pipes (temperature of heating or cooling medium) and the space or surface is calculated using thermal resistances. The concept is shown in Figure 3. An equivalent resistance, RHC, between the heating or cooling medium to a fictive core (or heat conduction layer) at the position of the pipes is determined. This resista
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2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Umweltgerechte Gebäudeplanung - Planung, Auslegung, Installation und Steuerung flächenintegrierter Strahlheizungs- und -kühlsysteme - Teil 2: Bestimmung der Auslegungs-Heiz- bzw. Kühlleistung (ISO 11855-2:2012)012)Conception de l'environnement des bâtiments - Conception, dimensionnement, installation et contrôle des systèmes intégrés de chauffage et de refroidissement par rayonnement - Partie 2 : Détermination de la puissance calorifique et frigorifique à la conception (ISO 11855-2:2012)Building environment design - Design, dimensioning, installation and control of embedded radiant heating and cooling systems - Part 2: Determination of the design heating and cooling capacity (ISO 11855-2:2012)91.140.30VLVWHPLVentilation and air-conditioning91.140.10Sistemi centralnega ogrevanjaCentral heating systemsICS:Ta slovenski standard je istoveten z:FprEN ISO 11855-2kSIST FprEN ISO 11855-2:2015en,fr,de01-junij-2015kSIST FprEN ISO 11855-2:2015SLOVENSKI
STANDARD



kSIST FprEN ISO 11855-2:2015



EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
FINAL DRAFT
FprEN ISO 11855-2
January 2015 ICS 91.140.10; 91.140.30 English Version
Building environment design - Design, dimensioning, installation and control of embedded radiant heating and cooling systems - Part 2: Determination of the design heating and cooling capacity (ISO 11855-2:2012)
Conception de l'environnement des bâtiments - Conception, dimensionnement, installation et contrôle des systèmes intégrés de chauffage et de refroidissement par rayonnement - Partie 2 : Détermination de la puissance calorifique et frigorifique à la conception (ISO 11855-2:2012)
Umweltgerechte Gebäudeplanung - Planung, Auslegung, Installation und Steuerung flächenintegrierter Strahlheizungs- und -kühlsysteme - Teil 2: Bestimmung der Auslegungs-Heiz- bzw. Kühlleistung (ISO 11855-2:2012)012) This draft European Standard is submitted to CEN members for unique acceptance procedure. 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, Former Yugoslav Republic of Macedonia, 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.
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:
Avenue Marnix 17,
B-1000 Brussels © 2015 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. FprEN ISO 11855-2:2015 EkSIST FprEN ISO 11855-2:2015



FprEN ISO 11855-2:2015 (E) 2 Contents Page Foreword .3 kSIST FprEN ISO 11855-2:2015



FprEN ISO 11855-2:2015 (E) 3 Foreword The text of ISO 11855-2:2012 has been prepared by Technical Committee ISO/TC 205 “Building environment design” of the International Organization for Standardization (ISO) and has been taken over as FprEN ISO 11855-2:2015 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 Unique Acceptance Procedure. This standard is applicable for design, construction and operation of radiant heating and cooling systems. The methods defined in part 2 are intended to determine the design heating or cooling capacity used for the design and evaluation of the performance of the system. For identifying product characteristics by testing and proving the thermal output of heating and cooling surfaces embedded in floors, ceilings and walls the standard series EN 1264 can be used. Endorsement notice The text of ISO 11855-2:2012 has been approved by CEN as FprEN ISO 11855-2:2015 without any modification. kSIST FprEN ISO 11855-2:2015



kSIST FprEN ISO 11855-2:2015



Reference numberISO 11855-2:2012(E)© ISO 2012
INTERNATIONAL STANDARD ISO11855-2First edition2012-10-01Building environment design — Design, dimensioning, installation and control of embedded radiant heating and cooling systems — Part 2: Determination of the design heating and cooling capacity Conception de l'environnement des bâtiments — Conception, construction et fonctionnement des systèmes de chauffage et de refroidissement par rayonnement — Partie 2: Détermination de la puissance calorifique et frigorifique à la conception
kSIST FprEN ISO 11855-2:2015



ISO 11855-2:2012(E)
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ISO 2012 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.
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© ISO 2012 – All rights reserved
kSIST FprEN ISO 11855-2:2015



ISO 11855-2:2012(E) © ISO 2012 – All rights reserved
iii Contents Page Foreword . iv Introduction . v 1 Scope . 1 2 Normative references . 1 3 Terms and definitions . 2 4 Symbols and abbreviations . 2 5 Concept of the method to determine the heating and cooling capacity . 3 6 Heat exchange coefficient between surface and space . 4 7 Simplified calculation methods for determining heating and cooling capacity or surface temperature . 6 7.1 Universal single power function . 7 7.2 Thermal resistance methods . 9 8 Use of basic calculation programs . 11 8.1 Basic calculation programs . 11 8.2 Items to be included in a complete computation documentation . 11 9 Calculation of the heating and cooling capacity . 12 Annex A (normative)
Calculation of the heat flux . 13 Annex B (normative)
General resistance method . 36 Annex C (normative)
Pipes embedded in wooden construction . 42 Annex D (normative)
Method for verification of FEM and FDM calculation programs . 50 Annex E (normative)
Values for heat conductivity of materials and air layers . 54 Bibliography . 56
kSIST FprEN ISO 11855-2:2015



ISO 11855-2:2012(E) iv
© ISO 2012 – All rights reserved 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 11855-2 was prepared by Technical Committee ISO/TC 205, Building environment design. ISO 11855 consists of the following parts, under the general title Building environment design — Design, dimensioning, installation and control of embedded radiant heating and cooling systems:  Part 1: Definition, symbols, and comfort criteria  Part 2: Determination of the design and heating and cooling capacity  Part 3: Design and dimensioning  Part 4: Dimensioning and calculation of the dynamic heating and cooling capacity of Thermo Active Building Systems (TABS)  Part 5: Installation  Part 6: Control Part 1 specifies the comfort criteria which should be considered in designing embedded radiant heating and cooling systems, since the main objective of the radiant heating and cooling system is to satisfy thermal comfort of the occupants. Part 2 provides steady-state calculation methods for determination of the heating and cooling capacity. Part 3 specifies design and dimensioning methods of radiant heating and cooling systems to ensure the heating and cooling capacity. Part 4 provides a dimensioning and calculation method to design Thermo Active Building Systems (TABS) for energy-saving purposes, since radiant heating and cooling systems can reduce energy consumption and heat source size by using renewable energy. Part 5 addresses the installation process for the system to operate as intended. Part 6 shows a proper control method of the radiant heating and cooling systems to ensure the maximum performance which was intended in the design stage when the system is actually being operated in a building. kSIST FprEN ISO 11855-2:2015



ISO 11855-2:2012(E) © ISO 2012 – All rights reserved
v Introduction The radiant heating and cooling system consists of heat emitting/absorbing, heat supply, distribution, and control systems. The ISO 11855 series deals with the embedded surface heating and cooling system that directly controls heat exchange within the space. It does not include the system equipment itself, such as heat source, distribution system and controller.
The ISO 11855 series addresses an embedded system that is integrated with the building structure. Therefore, the panel system with open air gap, which is not integrated with the building structure, is not covered by this series.
The ISO 11855 series shall be applied to systems using not only water but also other fluids or electricity as a heating or cooling medium.
The object of the ISO 11855 series is to provide criteria to effectively design embedded systems. To do this, it presents comfort criteria for the space served by embedded systems, heat output calculation, dimensioning, dynamic analysis, installation, operation, and control method of embedded systems. kSIST FprEN ISO 11855-2:2015



kSIST FprEN ISO 11855-2:2015



INTERNATIONAL STANDARD ISO 11855-2:2012(E) © ISO 2012 – All rights reserved 1 Building environment design — Design, dimensioning, installation and control of embedded radiant heating and cooling systems — Part 2: Determination of the design heating and cooling capacity 1 Scope This part of ISO 11855 specifies procedures and conditions to enable the heat flow in water based surface heating and cooling systems to be determined relative to the medium differential temperature for systems. The determination of thermal performance of water based surface heating and cooling systems and their conformity to this part of ISO 11855 is carried out by calculation in accordance with design documents and a model. This should enable a uniform assessment and calculation of water based surface heating and cooling systems. The surface temperature and the temperature uniformity of the heated/cooled surface, nominal heat flow density between water and space, the associated nominal medium differential temperature, and the field of characteristic curves for the relationship between heat flow density and the determining variables are given as the result. This part of ISO 11855 includes a general method based on Finite Difference or Finite Element Methods and simplified calculation methods depending on position of pipes and type of building structure. The ISO 11855 series is applicable to water based embedded surface heating and cooling systems in residential, commercial and industrial buildings. The methods apply to systems integrated into the wall, floor or ceiling construction without any open air gaps. It does not apply to panel systems with open air gaps which are not integrated into the building structure.
The ISO 11855 series also applies, as appropriate, to the use of fluids other than water as a heating or cooling medium. The ISO 11855 series is not applicable for testing of systems. The methods do not apply to heated or chilled ceiling panels or beams. 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 11855-1:2012, Building environment design — Design, dimensioning, installation and control of embedded radiant heating and cooling systems — Part 1: Definition, symbols, and comfort criteria EN 1264-2, Water based surface embedded heating and cooling systems — Part 2: Floor heating: Prove methods for the determination of the thermal output using calculation and test methods kSIST FprEN ISO 11855-2:2015



ISO 11855-2:2012(E) 2
© ISO 2012 – All rights reserved 3 Terms and definitions For the purposes of this document, the terms and definitions given in ISO 11855-1:2012 apply. 4 Symbols and abbreviations For the purposes of this document, the symbols and abbreviations in Table 1 apply. Table 1 — Symbols and abbreviations Symbol Unit Quantity i — Parameter factors for calculation of characteristic curves
AA m2 Surface of the occupied area
AF m2 Surface of the heating/cooling surface area
AR m2 Surface of the peripheral area
bu — Calculation factor depending on the pipe spacing
B, BG, B0 W/(m2K) Coefficients depending on the system
D m External diameter of the pipe, including sheathing where used
da m External diameter of the pipe di m Internal diameter of the pipe dM m External diameter of sheathing
cW kJ/(kgK) Specific heat capacity of water
ht W/(m2K) Total heat exchange coefficient (convection + radiation) between surface and space
KH W/(m2K) Equivalent heat transmission coefficient
KWL — Parameter for heat conducting devices
kfin — Parameter for heat conducting devices
kCL — Parameter for heat conducting layer
LWL m Width of heat conducting devices
Lfin m Width of fin (horizontal part of heat conducting device seen as a heating fin)
LR m Length of installed pipes
m — Exponents for determination of characteristic curves
mH kg/s Design heating/cooling medium flow rate
n, nG — Exponents
q W/m2 Heat flux at the surface
qA W/m2 Heat flux in the occupied area
qdes W/m2 Design heat flux
qG W/m2 Limit heat flux qN W/m2 Nominal heat flux qR W/m2 Heat flux in the peripheral area
qu W/m2 Outward heat flux Ro m2K/W Partial inwards heat transmission resistance of surface structure
Ru m2K/W Partial outwards heat transmission resistance of surface structure
R,B m2K/W Thermal resistance of surface covering
kSIST FprEN ISO 11855-2:2015



ISO 11855-2:2012(E) © ISO 2012 – All rights reserved 3 R,ins m2K/W Thermal resistance of thermal insulation
sh m In Type B systems, thickness of thermal insulation from the outward edge of the insulation to the inward edge of the pipes (see Figure 2)
sl m In Type B systems, thickness of thermal insulation from the outward edge of the insulation to the outward edge of the pipes (see Figure 2)
sins m Thickness of thermal insulation sR m Pipe wall thickness su m Thickness of the layer above the pipe sWL m Thickness of heat conducting device S m Thickness of the screed (excluding the pipes in type A systems)
W m Pipe spacing
 W/(m2K) Heat exchange coefficient
s,max °C Maximum surface temperature
s,min °C Minimum surface temperature
i °C Design indoor temperature
m °C Temperature of the heating/cooling medium
R °C Return temperature of heating/cooling medium
V °C Supply temperature of heating/cooling medium
u °C Indoor temperature in an adjacent space
H K Heating/cooling medium differential temperature
H,des K Design heating/cooling medium differential temperature
H,G K Limit of heating/cooling medium differential temperature
N K Nominal heating/cooling medium differential temperature
V K Heating/cooling medium differential supply temperature
V,des K Design heating/cooling medium differential supply temperature
 W/(mK) Thermal conductivity
 K Temperature drop V R  — Conversion factor for temperatures
 — Content by volume of the attachment burrs in the screed
5 Concept of the method to determine the heating and cooling capacity A given type of surface (floor, wall, ceiling) delivers, at a given average surface temperature and indoor temperature (operative temperature i), the same heat flux in any space independent of the type of embedded system. It is therefore possible to establish a basic formula or characteristic curve for cooling and a basic formula or characteristic curve for heating, for each of the type of surfaces (floor, wall, ceiling), independent of the type of embedded system, which is applicable to all heating and cooling surfaces (see Clause 6). Two methods are included in this part of ISO 11855:  simplified calculation methods depending on the type of system (see Clause 7);  Finite Element Method and Finite Difference Method (see Clause 8). kSIST FprEN ISO 11855-2:2015



ISO 11855-2:2012(E) 4
© ISO 2012 – All rights reserved Different simplified calculation methods are included in Clause 7 for calculation of the surface temperature (average, maximum and minimum temperature) depending on the system construction (type of pipe, pipe diameter, pipe distance, mounting of pipe, heat conducting devices, distribution layer) and construction of the floor/wall/ceiling (covering, insulation layer, trapped air layer, etc.). The simplified calculation methods are specific for the given type of system, and the boundary conditions listed in Clause 7 shall be met. In the calculation report, it shall be clearly stated which calculation method has been applied. In case a simplified calculation method is not available for a given type of system, either a basic calculation using two or three dimensional finite element or finite difference method can be applied (see Clause 8 and Annex D). NOTE In addition, laboratory testing (for example EN 1264-2:2008, Clause 9) may be applied. Based on the calculated average surface temperature at given combinations of medium (water) temperature and space temperature, it is possible to determine the steady state heating and cooling capacity (see Clause 9). 6 Heat exchange coefficient between surface and space The relationship between the heat flux and mean differential surface temperature [see Figure 1 and Equations (1) to (4)] depends on the type of surface (floor, wall, ceiling) and whether the temperature of the surface is lower (cooling) or higher (heating) than the space temperature.
Figure 1 — Basic characteristic curve for floor heating and ceiling cooling kSIST FprEN ISO 11855-2:2015



ISO 11855-2:2012(E) © ISO 2012 – All rights reserved 5 For floor heating and ceiling cooling in Figure 1, the heat flow density q is given by: q = 8,92 (S,m i)1,1 (W/m2) (1) where S,m is the average surface temperature in°C; i is the nominal indoor operative temperature in °C. For other types of surface heating and cooling systems, the heat flux q is given by: Wall heating and wall cooling: q = 8 (|s,m i |) (W/m2)
(2) Ceiling heating: q = 6 (|s,m i |) (W/m2)
(3) Floor cooling: q = 7 (|s,m i |) (W/m2)
(4) The heat transfer coefficient is combined convection and radiation. NOTE In many building system simulations using dynamic computer models, the heat transfer is often split up in a convective part (between heated/cooled surface and space air) and a radiant part (between heated/cooled surface and the surrounding surfaces or sources). The radiant heat transfer coefficient may in the normal temperature range 15-30 °C be fixed to 5,5 W/m2K. The convective heat transfer coefficient depends on type of surface, heating or cooling, air velocity (forced convection) or temperature difference between surface and air (natural convection). For using the simplified calculation method in Annex A the characteristic curves present the heat flux as a function of the difference between the heating/cooling medium temperature and the indoor temperature. For the user of Annex A, this means not to do any calculations by directly using values of heat exchange coefficients. Consequently, Annex A does not include values for such an application or special details or equations concerning heat exchange coefficients on heating or cooling surfaces. Thus, the values . of Table A.12 of Annex A are not intended to calculate the heat flux directly. In fact, they are provided exclusively for the conversion of characteristic curves in accordance with Equation (A.32) in Clause A.3. For simplifications these calculations are based on the same heat exchange coefficient for floor cooling and ceiling heating, 6,5 W/m2K. For every surface heating and cooling system, there is a maximum allowable heat flux, the limit heat flux qG. This is determined for a selected design indoor room temperature of i (for heating, often 20 °C and for cooling, often 26 °C) at the maximum or minimum surface temperature F,max and a temperature drop  = 0 K. For the calculations, the centre of the heating or cooling surface area, regardless of the type of system, is used as a reference point for S,max. The average surface temperature, S,m, which determines the heat flow density (refer to the basic characteristic curve) is linked with the maximum or minimum surface temperature: S,m  S,max and. S,m  S,min always applies. The attainable value, S,m, depends not only on the type of system, but also on the operating conditions (temperature drop  = V R, outward heat flow qu and heat resistance of the covering R,B). The following assumptions form the basis for calculation of the heat flux:  heat transfer between the heated or cooled surface and the space occurs in accordance with the basic characteristic curve; kSIST FprEN ISO 11855-2:2015



ISO 11855-2:2012(E) 6
© ISO 2012 – All rights reserved  the temperature drop  = 0. The dependence of the characteristic curve on the temperature drop is determined by using the logarithmically determined mean differential heating medium temperature H [see Equation (1)];  turbulent flow in pipe: mkgdhm; Hi4000 no lateral heat flow. 7 Simplified calculation methods for determining heating and cooling capacity or surface temperature Two types of simplified calculation methods can be applied according to this part of ISO 11855:  one method is based on a single power function product of all relevant parameters developed from the finite element method (FEM);  another method is based on calculation of equivalent thermal resistance between the temperature of the heating or cooling medium and the surface temperature (or room temperature). A given system construction can only be calculated with one of the simplified methods. The correct method to apply depends on the type of system, A to G (position of pipes, concrete or wooden construction) and the boundary conditions listed in Table 2. Table 2 — Criteria for selection of simplified calculation method Pipe position Type of system Figure Boundary conditions Reference to method In screed Thermally decoupled from the structural base of the building by thermal insulation A, C 2 a) W  0,050 m su  0,01 m 0,008 m  d  0,03 m su/e  0,01 7.1 A.2.2 In insulation, conductive devices Not wooden constructions except for weight bearing and thermal diffusion layer B 2 b) 0,05 m  W  0,45 m
0,014 m  d  0,022 m 0,01 m  su/e  0,18 7.1 A.2.3 Plane section system
D 2 c)
7.1, A.2.4 In concrete slab
E 4 ST /W  0,3 7.2, B.1 Capillar tubes in concrete surface
F 5 da/W  0,2
7.2, B.2 Wooden constructions, pipes in sub floor or under sub floor, conductive devices G 6 wl  10 surroundingmaterial SWL   0,01
7.2, Annex C
kSIST FprEN ISO 11855-2:2015



ISO 11855-2:2012(E) © ISO 2012 – All rights reserved 7 7.1 Universal single power function The heat flux between embedded pipes (temperature of heating or cooling medium) and the space is calculated by the general equation: imiiqBaH()û (W/m2) (5) where B is a system-dependent coefficient in W/(m2K). This depends on the type of system; ()imiia is the power product, which links the parameters of the structure (surface covering, pipe spacing, pipe diameter and pipe covering). 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. This method shall only be used for system configurations meeting the boundary conditions listed for the different types of systems in Annex A.
a)
Type A and C Key 1 floor covering 2 weight bearing and thermal diffusion layer (cement screed, anhydrite screed, asphalt screed) 3 thermal insulation 4 structural bearing kSIST FprEN ISO 11855-2:2015



ISO 11855-2:2012(E) 8
© ISO 2012 – All rights reserved
b)
Type B Key 1 floor covering 2 weight bearing and thermal diffusion layer (cement screed, anhydrite screed, asphalt screed, wood) 3 heat diffusion devices 4 thermal insulation 5 structural bearing kSIST FprEN ISO 11855-2:2015



ISO 11855-2:2012(E) © ISO 2012 – All rights reserved 9
c)
Type D Key 1 floor covering R, B 2 weight bearing and thermal diffusion layer (cement screed, anhydrite screed, asphalt screed, timber) 3 thermal insulation 4 structural bearing Figure 2 — System types A, B and C covered by the method in Annex A 7.2 Thermal resistance methods The heat flux between embedded pipes (temperature of heating or cooling medium) and the space or surface is calculated using thermal resistances. The concept is shown in Figure 3. An equivalent resistance, RHC, between the heating or cooling medium to a fictive core (or heat conduction layer) at the position of the pipes is determined. This resistance includes the influence of type of pipe, pipe distance and method of pipe installation (in concrete, wooden construction, etc.). In this way a fictive core temperature is calculated. The heat transfer between this fictive layer and the surfaces, Ri and Re (or space and neighbour space) is calculated using linear resistances (adding of resistance of the layers above and below the heat conductive layer). The equivalent resistance of the hea
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