ISO 18566-3:2017

Building environment design — Design, test methods and control of hydronic radiant heating and cooling panel systems — Part 3: Design of ceiling mounted radiant panels

ISO 18566-3:2017 specifies the design of ceiling mounted radiant panels. ISO 18566-3:2017 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. ISO 18566-3:2017 applies to all types of prefabricated radiant panels that are part of the room periphery. ISO 18566-3:2017 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.

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

General Information

• Status: Published
• Publication Date: 12-Jul-2017
• ICS: 91.040.01 - Buildings in general
• Technical Committee: ISO/TC 205 - Building environment design
• Drafting Committee: ISO/TC 205/WG 8 - Radiant heating and cooling systems
• Current Stage: 9093 - International Standard confirmed
• Completion Date: 07-Mar-2023

Standards Content (Sample)

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 18566-3:2017(E)
©
ISO 2017

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ISO 18566-3:2017(E)

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© ISO 2017, Published in Switzerland
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ii © ISO 2017 – All rights reserved

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ISO 18566-3:2017(E)

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
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ISO 18566-3:2017(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 documents 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).
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on 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 the following
URL: w w w . i s o .org/ iso/ foreword .html.
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.
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ISO 18566-3:2017(E)

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.
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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.
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ISO 18566-3:2017(E)

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 transfer from or to its surface will reduce the performance of the
system. Thermal resistance to the heat flow may vary considerably among different panels, depending
on the type of bond between the piping (wiring) and the panel material. Factors such as corrosion or
adhesion defects between lightly touching surfaces and the method of maintaining contact may change
the bond with time. The actual thermal resistance of any proposed system should be verified by testing.
Specific resistance and performance data, when available, should be obtained from the manufacturer.
Panel thermal resistances include:
— r : thermal resistance of pipe wall per unit pipe spacing in a hydronic system, m·K/W;
t
— r : thermal resistance between pipe (electric cable) and panel per unit spacing, m·K/W;
s
2
— r : thermal resistance of panel, m ·K/W;
p
2
— r : thermal resistance of panel covers, m ·K/W;
c
2
— r : characteristic panel thermal resistance, m ·K/W.
u
For pipe spacing M ,
p
rr=+Mr Mr++r
ut ps pp c
When the pipes are embedded in the panel, r may be neglected. However, if they are attached to the
s
panel, r may be significant, depending on the quality of bonding. Table A.1 gives typical r values for
s s
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ISO 18566-3:2017(E)

various ceiling panels. The value of r may be calculated if the characteristic panel thickness x and
p p
the thermal conductivity k of the panel material are known (see Annex A).
p
If the pipes are embedded in the panel,
D
o
x −
p
2
r =
p
k
p
where D = outside diameter of the pipe.
o
If the pipes are attached to the panel,
x
p
r =
p
k
p
Thermal resistance per unit spacing of a circular pipe with an inside diameter D and thermal
i
conductivity k is
t
ln DD/
()
oi
r =
t
2pk
t
In an electric cable, r =0 .
t
In metal pipes, r is virtually the fluid-side thermal resistance.
t
1
r =
t
hD
i
5.3 Panel heat loss or gain
Heat transferred from the upper surface of ceiling panels is considered as a panel heat loss. Panel heat
losses are part of the building heat loss if the heat is transferred outside of the building. If the heat is
transferred to another heated space, the panel loss is a source of heat for that space instead. In either
case, the magnitude of panel loss should be determined. Panel heat loss to space outside the room
should be kept to a reasonable amount by insulation.
5.4 Water velocity in pipes
At the design stage, attention should be given to proper water velocity. Water velocity that is too low
causes laminar flow, which reduces internal heat exchange. Generally, the heat exchange coefficient
within the range of turbulent flows including the transition area is different from that of laminar
flows. Approximately, it can be assumed that the heat exchange coefficient of turbulent flow is about
2 2
2 200 W/m ·K and that of laminar flow is about 200 W/m ·K. Both values are average values. Flow
characteristics can be determined by the internal diameter of the pipe, the average velocity of the flow
and the kinematic viscosity of the water.
The maximum water velocity per loop depends on the selection of pumps. When the temperature
differences between supply and return water are decreased, the water velocity should be increased.
The higher the water velocity, the higher the friction loss, and more pump energy is required. Most
loops are designed according to energy criteria with a pressure drop between 10 kPa and 25 kPa.
Noise from entrained air, high-velocity or high-pressure-drop devices, or pump and pipe vibrations
should be avoided. Water velocities should be high enough to prevent separated air from accumulating
and causing air binding. Where possible, avoid automatic air venting devices over ceilings of occupied
spaces. In general, noise can occur at high velocities. Make sure that the ceiling’s water velocities will
not fall below the minimum of 0,25 m/s for the 12 mm inside diameter copper pipe. Also, the maximum
velocities should not exceed 1,2 m/s for the 12 mm inside diameter copper pipe.
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ISO 18566-3:2017(E)

5.5 Surface condensation
To prevent the surface condensation problems, the surface temperature of the radiant ceiling can be
controlled to be above the dew point temperature. For this purpose, it is necessary to monitor the air
temperature and air humidity levels. In simple manners, the supply water temperature to the panels
should be controlled to avoid the possibility of surface condensation.
To prevent condensation on the room side of cooling panels, the panel water supply temperature should
be maintained at least 1 K above the room design dew point temperature. This minimum difference is
recommended to allow for the normal drift of temperature controls for the water and air systems, and
also to provide a factor of safety for temporary increase in space humidity.
The most frequently applied method of dehumidification uses cooling coils. If the main cooling coil is
six rows or more, the dew point of the leaving air will approach the temperature of the leaving water.
The cooling water leaving the dehumidifier can then be used for the panel water circuit.
Several chemical dehumidification methods are available to control latent and sensible loads separately.
In one application, cooling tower water is used to remove heat from the chemical drying process, and
additional sensible cooling is necessary to cool the dehumidified air to the required system supply air
temperature.
When chemical dehumidification is used, hygroscopic chemical-type dew point controllers are required
at the central apparatus and at various zones to monitor dehumidification.
When cooled ceiling panels are used with a variable air volume (VAV) system, the air supply rate should
be near the maximum volume to assure adequate dehumidification before the cooling ceiling panels are
activated.
5.6 Water distribution and piping system
Hydronic radiant panels can be used with two-pipe, three-pipe and four-pipe distribution systems.
Figure 1 shows the arrangement of a typical system. It is common to design for a 10 K temperature drop
for heating across a given grid and a 3 K rise for cooling, but larger temperature differentials may be
used, if applicable.
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ISO 18566-3:2017(E)

4
1
3
2
12
5
8
6
9
13
7
10
14
11
Key
1 panels 8 water heater
2 choke valve 9 supply
3 zone valves (optional) 10 primary cooling coil
4 air sep. 11 refrigeration chiller
5 secondary water pump 12 exp. tank
6 seco
...