ISO 18566-3:2017

INTERNATIONAL ISO
STANDARD 18566-3
First edition
2017-06
Building environment design —
Design, test methods and control of
hydronic radiant heating and cooling
panel systems —
Part 3:
Design of ceiling mounted radiant
panels
Conception de l’environnement des bâtiments — Conception,
méthodes d’essai et contrôle des systèmes de panneaux hydroniques
radiants de chauffage et de refroidissement —
Partie 3: Conception des panneaux radiants montés au plafond
Reference number
©
ISO 2017
© ISO 2017, Published in Switzerland
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ii © ISO 2017 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols . 1
5 General design consideration . 2
5.1 General . 2
5.2 Panel thermal resistance . 2
5.3 Panel heat loss or gain . 3
5.4 Water velocity in pipes . 3
5.5 Surface condensation . 4
5.6 Water distribution and piping system . 4
6 Design processes of hydronic panel systems . 6
6.1 General . 6
6.2 Cooling operation . 6
6.3 Heating operation . 8
Annex A (informative) Thermal resistance of ceiling panels and thermal conductivity of
typical pipe material .10
Annex B (informative) Heat transfer by panel surfaces .12
Bibliography .14
Foreword
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This document was prepared by Technical Committee ISO/TC 205, Building environment design.
A list of all parts in the ISO 18566 series can be found on the ISO website.
iv © ISO 2017 – All rights reserved

Introduction
There are various types of hydronic radiant heating and cooling systems: ceiling mounted radiant
panels, chilled beams, pipe embedded ceilings, walls, and floors. In those system alternatives, ceiling
mounted radiant panels are widely used and frequently installed on T-bar grids designed to support
the dropped acoustical ceiling. The ceiling mounted radiant panels are top loaded with thermal
insulation to prevent heat gain from or loss to the plenum space. In some cases, free hanging metal
panels suspended under the room ceiling by wire hangers without topside insulation are also used for
space heating and cooling. Both top and bottom surfaces of the free-hanging metal panel are used as
heat transfer surfaces. In principle, ceiling mounted radiant panel systems are able to accommodate
varying space sensible loads by controlling panel surface temperature. Heat is transferred from the
radiant panel by the heat transfer mechanisms of convection and radiation.
Generally, low temperature radiant heating and high temperature radiant cooling are classified as
embedded radiant heating and cooling systems and ceiling mounted radiant panel systems.
While ISO 11855 is for embedded radiant heating and cooling systems without an open air gap,
ISO 18566 is for radiant heating and cooling panel systems with an open air gap. Because the system
specifications for ISO 18566 are different from those of ISO 11855, it was necessary to develop separate
ISO standards regarding the design and test methods of the cooling and heating capacity and control.
ISO 18566-1 specifies the comfort criteria, technical specifications and requirements which should be
considered in the manufacturing and installation of radiant heating and cooling systems. ISO 18566-2
provides the test facility and test method for heating and cooling capacity of ceiling mounted radiant
panels. ISO 18566-3 specifies the design considerations and design processes of ceiling mounted radiant
panels. ISO 18566-4 addresses the control of ceiling mounted radiant heating and cooling panels to
ensure the maximum performance which was intended in the design stage when the system is actually
being operated in a building.
ISO 18566 does not cover the panels that are embedded into the ceiling, wall or floor structure.
This document is partly based on EN 14240, EN 14037 and ASNI/ASHRAE Standard 138.
INTERNATIONAL STANDARD ISO 18566-3:2017(E)
Building environment design — Design, test methods and
control of hydronic radiant heating and cooling panel
systems —
Part 3:
Design of ceiling mounted radiant panels
1 Scope
This document specifies the design of ceiling mounted radiant panels.
This document is applicable to water-based heating and cooling panel systems (free hanging) in
residential, commercial and industrial buildings. The methods apply to systems mounted to the ceiling
construction with an open air gap.
This document applies to all types of prefabricated radiant panels that are part of the room periphery.
This document does not cover panels embedded into ceiling, wall or floor structures without open air
gap and hybrid (combined thermal radiation and forced-convection) ceiling panels.
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.
ISO 18566-1, Building environment design — Design, test methods and control of hydronic radiant heating
and cooling panel systems — Part 1: Definition, symbols, technical specifications and requirements
ISO 18566-2, Building environment design — Design, test methods and control of hydronic radiant heating
and cooling panel systems — Part 2: Determination of heating and cooling capacity of ceiling mounted
radiant panels
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 18566-1 apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at http:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
4 Symbols
For the purposes of this document, the symbols in ISO 18566-1 apply.
5 General design consideration
5.1 General
The ceiling mounted radiant panels work by circulating warm or cold water through a network of pipes
placed on the floor, wall or ceiling. Heat is gently radiated from these radiant panels into occupied
spaces, warming or cooling the objects in the area to create a comfortable environment. Radiant
heating and cooling panels can be installed in a single room or throughout an entire building, and it is
used for areas with normal and high ceilings. A variety of heat sources can be used, including boilers,
geothermal heat pumps, solar thermal systems and electric water heaters.
Ceiling mounted radiant panels function as heat exchangers between the room air and the chilled/hot
water. The ceiling panels absorb or emit heat from heat sources in a room and exchanges it with the
circulating chilled/hot water. The chilled or hot water is then pumped to a chiller or boiler. With radiant
panel systems, room thermal conditions are maintained primarily by direct transfer of radiant energy,
rather than by convection heating and cooling. Radiation of energy takes place between objects with
different surface temperatures. In order to provide acceptable thermal conditions, air temperature and
mean radiant temperature should be taken into account. See Annex B for details about heat transfer by
panel surfaces.
Compared with a conventional convective heating and cooling system, a radiant heating system can
achieve the same level of operative temperature at a lower air temperature and a radiant cooling system
at a higher air temperature. However, in all practical thermal environments, a radiation field has an
asymmetric feature to some degree. If the asymmetry is sufficiently large, it can cause discomfort. Also,
the thermal stratification of air may cause thermal discomfort. Therefore, these comfort criteria should
be considered in the design stage of ceiling mounted radiant panels. Ceiling mounted radiant panels are
generally built as an architectural finish product. Generally, the copper pipes are thermally bonded and
panel piping arrangements are in a serpentine pattern or in a parallel pattern. The design of heating
and cooling capacity per unit panel area is determined from the performance data rated for the test
standard. The smaller the temperature difference between chilled/hot water and ceiling surface is, the
more efficient the system becomes.
5.2 Panel thermal resistance
Thermal resistance in the panel to heat tran
...