ISO 18566-1:2017

INTERNATIONAL ISO
STANDARD 18566-1
First edition
2017-06
Building environment design —
Design, test methods and control of
hydronic radiant heating and cooling
panel systems —
Part 1:
Vocabulary, symbols, technical
specifications and requirements
Conception de l’environnement des bâtiments — Conception,
méthodes d’essai et contrôle des systèmes de panneaux hydroniques
radiants de chauffage et de refroidissement —
Partie 1: Vocabulaire, symboles, spécifications techniques et exigences
Reference number
ISO 18566-1:2017(E)
©
ISO 2017

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ISO 18566-1:2017(E)

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© ISO 2017, Published in Switzerland
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ISO 18566-1:2017(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols . 6
5 Comfort criteria . 9
5.1 General . 9
5.2 Radiant temperature asymmetry .10
5.3 Vertical air temperature difference .11
6 Technical specifications and requirements .12
6.1 Technical specifications and installation .12
6.1.1 Major types of radiant panels .12
6.1.2 Specification . .13
6.1.3 Installation .15
6.2 Technical performance .16
6.2.1 Thermal performance .16
6.2.2 Hydronic performance .16
6.2.3 Acoustic performance .16
6.3 Safety .16
6.3.1 Durability of the panel system .16
6.3.2 Indoor environment impact .17
6.4 Maintenance of conformity .17
Annex A (informative) Descriptions of different types of radiant heating and cooling
ceiling panels.19
Annex B (informative) Example of panel information sheet .25
Bibliography .26
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ISO 18566-1:2017(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 18566-1:2017(E)

Introduction
The radiant heating and cooling system consists of heat emitting/absorbing, heat supply, distribution,
and control systems. Typical applications are low temperature radiant heating and high temperature
radiant cooling. They are classified as embedded radiant heating and cooling systems and prefabricated
radiant heating and cooling 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 18566-1:2017(E)
Building environment design — Design, test methods and
control of hydronic radiant heating and cooling panel
systems —
Part 1:
Vocabulary, symbols, technical specifications and
requirements
1 Scope
This document specifies the design, test conditions and methods for the determination of the cooling
and heating capacity and control of radiant heating and cooling panels with an open air gap. This
document applies to all types of prefabricated radiant panels that are part of the room periphery such
as ceiling, walls and floor.
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 wall,
floor or ceiling construction with an open air gap.
This document does not cover panels embedded into ceiling, wall or floor structures and hybrid
(combined thermal radiation and forced-convection) ceiling panels.
This document specifies the definition, symbols, comfort criteria, technical specifications and
requirements of ceiling mounted radiant 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 18566-2, 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 following terms and definitions 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/
3.1
active length of the ceiling mounted radiant panel
length of the usable heating or cooling panel with identical cross section and without connection
components and covers, which are bonded together with the water flow components
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3.2
active surface of the ceiling mounted radiant panel
lower panel surface, of which the lateral edges are not included
3.3
asymmetric feature
difference between the plane radiant temperature of the two opposite sides of a small plane element
3.4
average unconditioned surface temperature
AUST
mean temperature value of the uncontrolled surfaces
3.5
breaking load
minimum breaking force, in kilonewtons, which is the lowest breaking strain of the rope when tested
to destruction
3.6
building management system
BMS
computer-based system installed in buildings that controls and monitors the building’s mechanical
and electrical equipment such as heating, cooling, ventilating, lighting, power, disaster prevention, and
security systems
3.7
characteristic equation
equation that gives the thermal output and cooling capacity as a function of the temperature difference
at constant water flow rate
3.8
connection component
any other component attached to the active length of the ceiling mounted radiant panel which is used
for connecting to the distribution system or for venting and draining
3.9
construction dimension
dimension of ceiling mounted radiant panel after installation inside the test booth
3.10
construction length
length of the ceiling mounted radiant panel including the collectors/headers but excluding the
connecting pieces to the heating pipe work
3.11
dedicated outdoor air system
DOAS
type of heating, ventilation and air-conditioning (HVAC) system that consists of two parallel systems:
a dedicated outdoor air ventilation system that handles latent loads and a parallel system to handle
sensible loads
3.12
dimensions of non-circular pipes
shape and all dimensions necessary to describe exactly the cross section of the pipe
3.13
direct heating or cooling surface
portion of the heating or cooling surface of the panel which is in contact with the water
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ISO 18566-1:2017(E)

3.14
distance between pipes
distance between the centre lines of two pipes in parallel
3.15
draught
unwanted local cooling of the body caused by air movement and air temperature
3.16
effective surface temperature
design panel surface temperature based on comfort criteria
3.17
emissivity
ratio of emissive power of a surface at a given temperature to that of the black body at the same
temperature and with the same surroundings
3.18
factory test pressure
pressure to which the panel is submitted during the manufacturing process
3.19
free hanging sail
element composed of one or more modules of a cooling installation which is additionally used for heating
Note 1 to entry: Depending on the use of the sails, they can be covered with thermal insulation or noise absorption
material.
3.20
heated and chilled ceiling surfaces
radiant ceiling panel surfaces which have different compositions and installation methods by
manufacturers
3.21
heating appliance
device to transfer heat in order to provide specific temperature conditions inside buildings
3.22
independent heating appliance
self-contained heating appliance which does not need to be connected to a remote heat source (e.g. a
boiler) as it contains its own heat source
3.23
indirect heating or cooling surface
portion of the heating or cooling surface of the panel which is in contact with air only
EXAMPLE Radiant sheet between the pipes.
3.24
inlet water temperature
bulk temperature of the water entering the ceiling mounted radiant panel
3.25
length of radiant sheet
length of the heat or cold transferring sheets
Note 1 to entry: Generally identical with the active length according to ISO 18566-2.
3.26
maximum operating pressure
maximum system pressure to which the panel may be submitted as stated by the manufacturer
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3.27
maximum surface temperature
maximum temperature permissible for physiological reasons or building fabrics, for calculation of the
limit curves, which may occur at a point on the surface (floor, wall, ceiling) in the occupied or peripheral
area depending on the particular usage at a temperature drop σ of the heating medium equal to 0
3.28
mean radiant temperature
MRT
uniform temperature of an imaginary enclosure in which the radiant heat transfer from the human
body is equal to the radiant heat transfer in the actual non-uniform enclosure
3.29
mean radiant temperature of room
temperature in a defined point of the room resulting from the radiation of all surrounding surfaces and
of the ceiling mounted radiant panel or heated ceiling surface
3.30
mean water temperature
arithmetical mean of inlet and outlet water temperature
3.31
minimum surface temperature
minimum temperature permissible for physiological reasons or building fabrics, for calculation of the
limit curves, which may occur at a point on the surface (floor, wall, ceiling) in the occupied or peripheral
area depending on the particular usage at a temperature drop σ of the heating medium equal to 0
3.32
model
ceiling mounted radiant panel or heated ceiling surface of defined construction, width and height
3.33
module
2
1 m of the active length of a ceiling mounted radiant panel, in relation to 1 m active surface of a heated
ceiling surface
3.34
nominal cooling capacity
cooling capacity at temperature difference of 8 K between room temperature and mean water
temperature
3.35
nominal modular cooling capacity
cooling capacity of one module at temperature difference of 8 K between room temperature and mean
water temperature
3.36
nominal temperature difference
temperature difference of 8 K between room temperature and mean water temperature
3.37
open or closed ceiling surface
open or closed active and non-active elements of chilled ceilings, which are additionally used for
heating, which are part of suspended ceilings and generally constructed modular from industrially
prefabricated elements
3.38
operative temperature
OT
uniform temperature of an enclosure in which an occupant would exchange the same amount of heat by
radiation plus convection as in the actual non-uniform environment
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ISO 18566-1:2017(E)

3.39
outlet water temperature
bulk temperature of the water leaving the ceiling mounted radiant panel
3.40
outside diameter of circular pipe
nominal diameter according to standard pipe dimensions
3.41
predicted mean vote
PMV
index that predicts the mean value of the votes of a large group of persons on the 7-point thermal
sensation scale (hot, warm, slightly warm, neutral, slightly cool, cool, cold), based on the heat balance of
the human body
3.42
predicted percentage of dissatisfied
PPD
index that establishes a quantitative prediction of the percentage of thermally dissatisfied people who
feel too cool or too warm
3.43
prefabricated ceiling mounted radiant panel
heat-transmitting device in the form of a heating or cooling element with width of 0,3 m up to 1,5 m
fitted with connection components and designed to operate on water flow heating facilities and/or in
cooling systems
3.44
radiant output
thermal output emitted downwards by radiation of the active length
3.45
radiant surface heating and cooling system
heating and cooling system that controls the temperature of indoor surfaces on the floor, walls, or ceiling
3.46
radiant asymmetry
difference between the plane radiant temperature of the two opposite sides of a small plane element
3.47
reference room temperature
temperature measured with a globe thermometer
3.48
suspended ceiling with integrated heating elements
single closed elements integrated in closed hanging ceilings and combined with non-active elements
which are used for heating and are thermally insulated on the upper side
3.49
temperature difference
difference between mean water temperature and reference room temperature
3.50
thermal output
sum of the products of the heating or cooled surfaces of a space with the associated design heat flow
densities
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ISO 18566-1:2017(E)

3.51
vertical air temperature difference
air temperature difference between head and ankles of a person
Note 1 to entry: 0,1 m and 1,1 m for sedentary and 0,1 m and 1,7 m above floor for standing.
3.52
water flow rate
volume of fluid passing through the ceiling mounted radiant panel per unit of time
4 Symbols
Symbol Unit Definition
2
A m surface area of the non-insulated walls
2
A m active surface of a heated ceiling surface module
a
2
A m installation surface area
i
2
A m active surface area of the ceiling mounted radiant panel
rp
c J/kg K specific heat capacity
p
D m inside diameter of the pipe
i
D m diameter for connection of inlet/outlet
i/o
D m outside diameter of pipe
o
d m distance between pipes
tub
h J/kg specific enthalpy
h J/kg inlet water enthalpy
1
h J/kg outlet water enthalpy
2
h mm height of the void including the height of the test sample
v
n
K constant of the characteristic equation
WK/
n
K constant of the characteristic equation of the active length/surface
act
act
WK/
K constant of the characteristic equation of the module
actM 2 n
actM
Wm/( K )
K constant of the characteristic equation of the active length
Cact n
Cact
Wm/( K )
K constant of the characteristic equation of the connection components
n
comp
comp
WK/
K constant of the characteristic equation of the module based on the
n
rto
act
Wm/( K )
rated thermal output
K constant of the characteristic equation of the construction length/
tot n
tot
WK/
surface
k W/m·K thermal conductivity of the panel material
p
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ISO 18566-1:2017(E)

k W/m·K thermal conductivity of the pipe material
t
L m active length of the ceiling mounted radiant panel
act
L m height of lateral edges
le
L m length of radiant sheet
sh
L m construction length
tot
L m length of tubes
tub
M kg dry mass
M m pipe spacing
p
3
m m water content
v
m kg mass of water
w
N — number of test points
n — exponent of the characteristic equation of the active length/surface
act
n — exponent of the characteristic equation of the active surface
Cact
n — exponent of the characteristic equation of the connection components
comp
n — exponent of the characteristic equation of the construction length/
tot
surface
PD % percentage dissatisfied
p kPa air pressure
p kPa maximum operating pressure
max
p kPa standard air pressure defined as 101,325 kPa (1,013 25 bar)
s
q kg/s water flow rate
m
R % percentage of radiant output
R — active area ratio
a
r % referred percentage of radiant output for each measuring point
r m·K/W thermal resistance of panel covers
c
r m·K/W thermal resistance of panel
p
r m·K/W thermal resistance between pipe (electric cable) and panel per unit
s
spacing
r m·K/W thermal resistance of pipe wall per unit tube spacing in a hydronic
t
system
r m·K/W characteristic panel thermal resistance
u
s m thickness of upper insulation
i
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ISO 18566-1:2017(E)

s m reproducibility tolerance
m
s m repeatability tolerance
o
s m thickness of sheet
sh
T K thermodynamic temperature
θ °C temperature
θ °C inlet water temperature
1
θ °C outlet water temperature
2
θ °C air temperature
a
θ °C mean water temperature
m
θ °C mean radiant temperature
mrad
θ °C reference room temperature
ref
θ °C mean surface temperature of the ceiling mounted radiant panel
rp
θ °C surface temperature of the inside surfaces of the test booth
w
θ surface temperature of the i inside surface of the test booth
w,i th
heat transfer coefficient (air–insulation–wall), i.e. U-value of i sur-
th
2
U W/(m K)
i
face (every wall, ceiling and floor structure) of the test booth
W m width of ceiling mounted radiant panel
rp
x m characteristic panel thickness
p
2 4 −8
σ W/(m K ) Stephan Boltzmann constant (5,67 × 10 )
ε — emissivity of the test sample
rp
τ s time interval
Φ W heat flow or thermal output from radiant panel
Φ W output of the active length
act
Φ W total heat flow in all enclosure walls
B
Φ W standard modular cooling capacity
CLs
Φ W measured cooling capacity of a ceiling mounted radiant panel
Cme
Φ W nominal cooling capacity of a ceiling mounted radiant panel
CN
Φ W output of connection components
comp
Φ W standard cooling capacity of a ceiling mounted radiant panel, cooling
CS
capacity at standard temperature difference and standard air pressure
Φ W rated thermal output
D
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ISO 18566-1:2017(E)

Φ W/m modular thermal output
L
2
W/m
Φ W/m standard modular thermal output
LS
2
W/m
Φ W measured output
me
Φ W standard output of a master panel of the primary set for interlabora-
M,s
tory comparisons
Φ W standard output of a master panel
O,s
Φ W radiant output
rad
Φ W total thermal output of simulators
S
Φ W total output
tot
Δθ K temperature difference
Δθ K nominal temperature difference (8 K) of a ceiling mounted radiant
cn
panel when cooling
Δθ K standard temperature difference (15 K) of a ceiling mounted radiant
cs
panel when cooling, reference room temperature 32 °C and mean
water temperature 17 °C
Δθ K measured temperature difference
me
Δθ K radiant temperature asymmetry
pr
Δθ K standard temperature difference of a ceiling mounted radiant panel
s
when heating (55 K), mean water temperature 75 °C and reference
room temperature 20 °C
5 Comfort criteria
5.1 General
Room thermal environment with ceiling mounted radiant panels is different from that with the
conventional all-air HVAC system. Compared with conventional all-air HVAC system, ceiling mounted
radiant panels can reduce the uncomfortable environment caused by draught and air temperature
differences between the human head and foot. The human head, which emits much of the body’s heat,
can more effectively emit that energy with the cool ceiling above. And the cooled ceiling can increase
the thermal comfort by making a radiatively cool face and temperate feet.
It is possible to maintain the space dry-bulb temperature higher with radiant panels and achieve the
desired thermal comfort. For example, a space at 26 °C with radiant cooling can give the perception of
a space at about 24 °C without radiant panels. This results in a reduction in the building cooling loads.
It also means that the conditioned ventilation supply air can remove more sensible cooling load since
there is a larger temperature rise as the air passes through the space.
With ceiling mounted radiant panel cooling, the heat rejection from the human body by radiation can
be increased from about 35 % without radiant panels to 50 % with radiant panels. Likewise, the heat
loss due to convection decreases from about 40 % without the radiant panels to about 30 % with. The
net effect is that less heat is rejected by perspiration in the presence of the radiant cooling field. Also,
the radiant asymmetry can be experienced by the occupant with radiant panels. With most of the
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ISO 18566-1:2017(E)

enclosure at 26 °C or below and the radiant panels at approximately 16 °C, up to 10 K radiant asymmetry
temperature differential exists.
People may be dissatisfied due to general thermal comfort and/or local thermal comfort parameters.
Thermal comfort requirements may limit the capacity and use of radiant surface heating and cooling
systems. According to ISO 7730, for the thermal comfort requirements in winter for people with mainly
sedentary activity (1,2 met, 1,0 clo), the operative temperature range is between 20 °C and 24 °C. In
summer, for people with mainly sedentary activity (1,2 met, 0,5 clo), it is between 23 °C and 26 °C.
This document presents the prediction methods for the general thermal sensation and degree of
discomfort (thermal dissatisfaction) of people exposed to moderate thermal environments. It enables
the analytical determination and interpretation of thermal comfort using calculation of predicted
mean vote (PMV) and predicted percentage of dissatisfied (PPD) and local thermal comfort, giving
the environmental conditions considered acceptable for general thermal comfort as well as those
representing local discomfort. Especially for designing of the radiant heating and cooling panel system,
it is important that thermal comfort is specified with regard to the radiant temperature asymmetry
and vertical air temperature difference. According to ISO 7730, the predicted per cent of dissatisfied
occupancy is less than 6 % as a result of 8 K or less radiant asymmetry. For most cases, only about 50 %
of the ceiling is chilled, so the effective mean radiant ceiling temperature of the two nearly equal areas
is close to 21 °C, resulting in a radiant asymmet
...