SIST EN 17671:2025

SLOVENSKI STANDARD
01-november-2025
Sistemi za ogrevanje in hlajenje z vodo v stavbah - Projektiranje sistemov za
hlajenje z vodo
Heating systems and water-based cooling systems in buildings - Design for water-based
cooling systems
Heizungsanlagen und wassergeführte Kühlanlagen in Gebäuden - Planung von
wassergeführten Kühlanlagen
Systèmes de chauffage et systèmes de refroidissement à eau dans les bâtiments -
Conception des systèmes de refroidissement à eau
Ta slovenski standard je istoveten z: EN 17671:2025
ICS:
91.140.30 Prezračevalni in klimatski Ventilation and air-
sistemi conditioning systems
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN 17671
EUROPEAN STANDARD
NORME EUROPÉENNE
August 2025
EUROPÄISCHE NORM
ICS 91.140.30
English Version
Heating systems and water-based cooling systems in
buildings - Design for water-based cooling systems
Systèmes de chauffage et systèmes de refroidissement Heizungsanlagen und wassergeführte Kühlanlagen in
à eau dans les bâtiments - Conception des systèmes de Gebäuden - Planung von wassergeführten Kühlanlagen
refroidissement à eau
This European Standard was approved by CEN on 16 June 2025.

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, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2025 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 17671:2025 E
worldwide for CEN national Members.

Contents Page
European foreword . 4
1 Scope . 5
2 Normative references . 6
3 Terms and definitions . 6
4 Symbols and subscripts . 10
4.1 Symbols . 10
4.2 Subscripts . 10
5 System design requirements . 11
5.1 General requirements . 11
5.2 Requirements for preliminary design information . 11
5.3 Chilling system . 12
5.3.1 General. 12
5.3.2 Sizing . 13
5.3.3 Devices for water-based heat rejection system (recooler) . 13
5.4 Primary and secondary distribution circuits . 13
5.4.1 General. 13
5.4.2 Requirements for the chilled water . 14
5.4.3 Flow rate . 14
5.4.4 Circulation pumps . 14
5.4.5 Pipework . 15
5.4.6 Hydronic balancing . 16
5.5 Cooling emission system – coolers . 16
5.5.1 General. 16
5.5.2 Sizing . 16
5.5.3 Positioning of coolers . 16
5.5.4 Protection against damage to buildings and installations. 17
5.5.5 Unnecessary cooling consumption . 17
5.5.6 Cleaning . 17
5.6 Cooling system controls . 17
5.6.1 General. 17
5.6.2 Central control . 17
5.6.3 Local temperature control . 18
5.6.4 Zone control . 18
5.6.5 Supply temperature control . 18
5.6.6 Time control of cooling . 19
5.7 Safety arrangements . 19
5.7.1 General. 19
5.7.2 Protection against temperatures falling below the minimum system safety
temperature . 20
5.7.3 Safety valves, rating, design and arrangements . 20
5.7.4 Flow control device . 20
5.7.5 Pressurization systems . 20
5.8 Operational requirements . 21
5.8.1 General. 21
5.8.2 Provision for monitoring operating conditions . 22
5.8.3 Temperature/power controller . 22
5.8.4 Pressure maintaining control device . 22
5.8.5 Filling and feeding device . 22
5.9 Thermal insulation . 22
5.10 Preventing corrosion . 24
5.11 Documentation . 24
5.12 Instructions for maintenance, operation and use . 24
5.13 Installation and commissioning . 24
Annex A (informative) Information for the design of diaphragm expansion vessels (static
pressurization and pressurization stations (dynamic pressurization) for closed
systems . 25
A.1 General . 25
A.2 Expansion vessel size calculation . 27
Annex B (informative) Hydraulic schemes for heating and cooling . 31
B.1 General . 31
Bibliography . 37

European foreword
This document (EN 17671:2025) has been prepared by Technical Committee CEN/TC 228 “Heating
systems and Water-based Cooling Systems in Buildings”, the secretariat of which is held by DIN.
This 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 2026, and conflicting national standards
shall be withdrawn at the latest by February 2026.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
Any feedback and questions on this document should be directed to the users’ national standards body.
A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organisations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the
United Kingdom.
1 Scope
This document specifies design criteria for closed water-based cooling systems in buildings and the
design of such systems is described. The definitions are aimed at achieving an appropriate level of
technical quality and maintaining the desired thermal indoor climate with minimum energy
consumption.
This document does not apply to systems for dissipating process heat from industrial processes. It also
does not apply to and does not amend product standards or product installation requirements.
This document is applicable to cooling systems of the following type (see also Figure 1):
1) devices for the water-based heat rejection of the chilling system;
2) devices for chilling and storage of chilled water;
3) devices for the distribution of chilled water;
4) devices for the absorption of heat (“cooling emission”);
5) control devices;
6) safety devices.
Key
HRS heat rejection system  DC1 primary distribution cicuit
RC recooler  DC2 secondary distribution cicuit
RC1 dry recooler  EM coolers (emission system)
RC2 cooling tower  EM1 cooling terminal
CS chilling system  EM2 coil
C chiller  EM3 embedded coolers
FC possible free cooling  EM4 fan coil unit
1 cooling water  3 chilled water
2 refrigerant  4 chilled water
Figure 1 — Schematic example of a water-based cooling system
This document does not cover additional safety aspects for water-based cooling systems with local
operating temperatures ≤ 0 °C. The other clauses of this document are still valid for systems with local
operating temperatures ≤ 0 °C.
This document also does not cover the chilling system itself, but only the parts of the chilling system
which are an integral part of the cooling system, including determination of the design performance.
Furthermore, this document does not cover:
— the requirements for installation or instructions for operation, maintenance and use;
— the design of the system components (e.g. recooler, chilling system, coolers, pipes, safety devices
etc.).
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
EN 1717, Protection against pollution of potable water in water installations and general requirements of
devices to prevent pollution by backflow
EN 12170, Heating systems in buildings — Procedure for the preparation of documents for operation,
maintenance and use — Heating systems requiring a trained operator
EN 12171, Heating systems in buildings — Procedure for the preparation of documents for operation,
maintenance and use — Heating systems not requiring a trained operator
EN 16798-1:2019, Energy performance of buildings — Ventilation for buildings — Part 1: Indoor
environmental input parameters for design and assessment of energy performance of buildings addressing
indoor air quality, thermal environment, lighting and acoustics — Module M1-6
EN 14336, Heating systems in buildings — Installation and commissioning of water based heating and
cooling systems
EN ISO 52000-1:2017, Energy performance of buildings — Overarching EPB assessment — Part 1:
General framework and procedures (ISO 52000-1:2017)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://www.iso.org/obp/
— IEC Electropedia: available at https://www.electropedia.org/
3.1
chilling system
configuration of interconnected components and appliances for the supply of chilled water to the
distribution system
3.2
chilled water
water on the heat-absorbing side of a chiller (primary and secondary circuit)
Note 1 to entry: Usually with a temperature ≤ 25 °C.
3.3
combined heating and cooling system
system used both for covering a heat load and the cooling load of a building, and for which there is a
temporary or permanent hydraulic connection between the two respective circuits
3.4
chiller
cooler
device for extracting heat from a cooled space
EXAMPLE A fan coil unit, embedded cooler, cooling terminal and coil.
3.5
cooling water
water on the heat-rejection side of a chiller
3.6
cooled space
space which, per design, is cooled to the specified internal design temperature and separated from
other spaces by building elements, walls etc
Note 1 to entry: Usually each single (cooled) room is considered a cooled space.
3.7
external air temperature
air temperature outside the building
3.8
external design temperature
external air temperature which is used for the calculation of the design cooling load
3.9
free cooling
cooling that uses the natural low temperature of the air, water or earth instead of mechanical
refrigeration
EXAMPLE By means of ventilation during the day or night or through the direct use of cooling towers, dry
coolers, seawater, groundwater or embedded coils with energy consumption for any pumps and fans.
Note 1 to entry: Auxiliary energy can be used to attain this effect.
3.10
passive cooling
building design approach that focuses on heat gain control and heat dissipation in a building and can
consist of a combination of free cooling and protection against heat gains
3.11
frost inhibitor
additive to water that lowers its freezing point
3.12
heat rejection system
part of the cooling system which emits the rejected heat produced by the chiller to the external
environment including pipes, valves, pumps and mixing systems
3.13
lockout
default condition resulting in a shutdown of the system and requiring a manual reset
Note 1 to entry: The intention of a lockout is to require the operator to investigate and eliminate the cause of the
lockout.
3.14
maximum operating pressure
maximum pressure at which the system, or parts of the system, is designed to operate
3.15
maximum operating temperature
maximum temperature at which the system, or parts of the system, is designed to operate
3.16
minimum operating temperature
minimum temperature at which the system, or parts of the system, is designed to operate
3.17
minimum system safety temperature
lowest temperature any component of the cooling system can accommodate
3.18
operative temperature
arithmetic average of the internal air temperature and the mean radiant temperature
3.19
design cooling load
heat flow (power) required to achieve the specified internal design temperature and/or humidity
conditions under external summer design conditions
3.20
partial cooling load
fraction of design cooling load occurring under typical dynamically varying cooling system operating
conditions
3.21
pressure limiting device
automatic operating device which prevents the maximum operating pressure from being exceeded
3.22
pressurization system
system equipment (diaphragm expansion vessels, compressor-controlled pressurization units and
pump-controlled pressurization units) for maintaining the pressure in closed cooling systems
Note 1 to entry: The equipment provides to maintain the system pressure between defined limits and ensures the
required minimal working pressure of the cooling system. The equipment holds the accruing expansion water
when the system water is heated and restores the volume when the cooling system is cooling down and
contracting. Due to the design of construction, the expansion system simultaneously protects the expansion water
from corrosion producing ingress of oxygen.
3.23
primary distribution circuit
part of the cooling system which distributes chilled water from the chilling system to the individual
cooling circuits including pipes, valves, pumps and mixing systems
3.24
secondary distribution circuit
part of the cooling system which distributes chilled water from the primary distribution circuit to the
individual coolers at the appropriate temperatures and/or flowrates including pipes, valves, pumps and
mixing systems
3.25
sealed system
cooling system in which the cooling medium is closed to the atmosphere
3.26
temperature controller
automatic device intended to keep the temperature at a set point
3.27
control
method of controlling the energy flow to a cooling emission system by changing the flow rate and/or
the flow temperature
3.28
central control
control at a central point
3.29
zone control
local control of a zone consisting of more than one space
3.30
local control
control locally on the basis of the temperature of the cooled space
3.31
zone
space or group of spaces with similar thermal characteristics
4 Symbols and subscripts
4.1 Symbols
For the purposes of this document, the symbols given in EN ISO 52000-1:2017 and the specific symbols
listed in Table 1 apply. Symbols and subscripts may have more than one denotation.
Table 1 — Symbols and units
Symbol Name Unit
ϑ temperature on the Celsius scale °C
ρ density
kg/m or kg/l
η utilization efficiency –
l heat conduction W/m·K
d diameter m
e expansion coefficient –
U thermal transmittance W/m K or W/m·K
V volume
m
h height m
p pressure Pa or bar
(1 bar = 100 000 Pa)
4.2 Subscripts
For the purposes of this document, the subscripts given in EN ISO 52000-1:2017, and the specific
subscripts listed in Table 2 apply. Subscripts may have several denotations.
Table 2 — Subscripts
Index Meaning/use
st static
sv safety valve
v vapor
O operating
ini initial
fin final
fil filling
e external
w wall
wr water reserve
ex expansion
N nominal
Index Meaning/use
max maximum
min minimal
5 System design requirements
5.1 General requirements
Cooling systems shall be designed and selected to provide satisfactory thermal comfort and to enable an
economically optimized operation with a minimum energy consumption within the framework of the
specified operating parameters. This includes operation at design cooling load and partial cooling loads.
The following general aspects shall be taken into account:
— external cooling loads shall be minimized e.g. by using external sunlight protection and sunshade
equipment;
NOTE In new constructions, this is combined with an appropriate design of the building and windows as well
as the use of materials with a high heat capacity.
— internal cooling loads shall be reduced as far as possible e.g. by using energy efficient lighting and
technical appliances;
— methods of passive- and free cooling shall be made use of first, where possible. Mechanical cooling
should only be activated if it is not otherwise possible to reduce the room temperatures in
accordance with the selected values (e.g. EN 16798-1:2019, B.1.2);
— simultaneous heating and cooling of individual rooms shall be avoided;
— chilled water temperatures shall be as high as possible in accordance with the respective cooling
emission system. Unnecessary low temperatures in the primary and secondary distribution circuits
shall be avoided;
— cooling water temperatures in the heat rejection circuit shall be as low as possible in accordance
with the respective heat rejection system e.g. by means of generously dimensioned recoolers.
5.2 Requirements for preliminary design information
The cooling system shall be designed so that it can be installed and operated in a way that does not
damage the building or other technical building systems.
The cooling system shall be designed with due consideration to: installation, commissioning, operation,
and maintenance of the entire system under design cooling load and partial cooling load conditions.
At the planning stage or during the progress of design, the following items shall be taken in
consideration and documented:
a) thermal characteristics of the building for calculation of cooling load and possible improvements
regarding energy savings;
b) external design temperature and air humidity for the design case;
c) internal design temperature;
d) method of design cooling load calculation;
e) permissible exceedances of the operative temperature according to EN 16798-1:2019, Table B.2;
f) energy sources for cooling;
g) position of the chiller, bearing in mind access for maintenance as well as the cooling water and
chilled water piping layout;
h) position of the heat rejection system. If possible protection against direct sunlight and
contamination in compliance with separate (e.g. hygienic) requirements of the heat rejection
system;
i) choice of suitable pressurization and degassing;
j) position of expansion vessels, filling point and pressure gauge;
k) facilities for filling and draining the system and parts;
l) power requirements of any attached system;
m) type and position of coolers and cooling surfaces;
n) type of control system for cooling and any attached systems, especially when controlled together
with heating systems;
o) pipework routing and laying method of the installation;
p) specifications for hydronic balancing of the system;
q) provisions for energy monitoring and management functions;
r) provisions for protection against condensation;
s) provisions for system filling and water treatment;
t) requirements for extra cooling capacity for intermittent operation (e.g. utility locking times) as well
as chilled water storage;
u) technical rooms, location and size.
5.3 Chilling system
5.3.1 General
According to 5.2 d), the method for determining the design cooling load shall be agreed upon with the
client. The chilling system shall be designed in such a way that it covers the determined design cooling
load (sensible and latent) of the building.
The chilling system shall be designed and dimensioned taking into account the type of chiller and the
type of heat rejection and its control mode.
The temperature in the distribution system shall be as high as possible with regard to the output and
operation of the coolers.
If necessary, a chilled water storage tank shall be installed. Sizing can be based on a maximum number
of operation cycles or minimum running time of the chiller.
5.3.2 Sizing
If the total cooling power is provided by more than one chiller, the following points shall be considered:
— the fraction of the cooling load supplied by each chiller, if necessary depending on their respective
running times;
— hydraulic balancing during simultaneous operation of multiple chillers;
— isolation of standby chillers;
— operational requirements, such as standby modes.
5.3.3 Devices for water-based heat rejection system (recooler)
The design of the heat rejection system shall consider the following points:
— minimizing return temperatures to the chiller;
— variable control of fans in dry coolers and cooling towers;
— hygenic aspects of wet cooling towers including water treatment requirements;
— noise aspects;
— connection to free cooling;
— minimizing the use of auxiliary energy.
The devices for the water-based heat rejection of the chiller (see Figure 1) shall be designed to ensure
rejection of heat in all operating states.
5.4 Primary and secondary distribution circuits
5.4.1 General
The primary and secondary distribution circuits shall be designed and dimensioned so that the desired
thermal indoor climate can be controlled and maintained, and the necessary cooling flows are available
at the coolers, and if necessary any attached systems.
The required temperatures and pressure at the coolers shall be maintained under design cooling load
and partial cooling load operating conditions, so as to minimize energy usage.
The distribution system shall be designed, placed and insulated such that cooling loss to the
surroundings is kept at a minimum.
If possible, the distribution system shall be placed so that the cooling emission from the system benefits
the building. Pipes, ducts, components, etc. shall if possible not be placed in areas with high
temperatures.
In case of combined heating/cooling systems, the higher volumetric flow rates required for cooling shall
be considered. Suitable components shall be used.
The distribution system, including sub-circuits, shall be designed so as to enable hydraulic balancing.
Consideration shall also be given to any variety of demand for connected systems. Consideration shall
be given to separate circuits for each type of cooling emission system, the zoning requirement of
buildings and the supply temperature and temperature difference of each cooling emission system.
Provision for filling, draining and venting shall be provided for each circuit.
5.4.2 Requirements for the chilled water
The requirements stated below also apply for the heat rejection system.
To ensure the quality of the chiller water and protect the system from malfunction, three factors should
be managed during the design phase:
— all chilled water distribution circuits should be designed to prevent air ingress and facilitate the
collection and removal of air during filling and operation;
— the rate of corrosion should be minimized by preventing oxygen ingress, selecting appropriate and
compatible materials and/or by specifying a chemical corrosion inhibitor;
— chilled water distribution systems should be designed and operated so that sedimentation of
suspended, circulating particulate matter and biological fouling are prevented. Design should
ensure that circulating solids are easily removed during operation (i.e. by use of an appropriate
filter).
The necessity of using frost inhibitors and chemicals in the chiller medium shall be considered. In
particular, repercussions on the environment and waste disposal of the medium shall be taken into
account. Wherever possible, the use of chemicals shall be avoided, but in some cases, the use of
chemicals can be the best option.
Regarding the chilled water, there are national documents in some countries with further guidelines.
National documents are available from the respective National Standardization Body.
When using frost inhibitors, the modification of the properties in the chiller medium shall be considered
in the selection and dimensioning of the system components (e.g. circulation pump, sealing materials),
in particular the modifications of the heat capacity, the viscosity and the corrosion potential.
All frost inhibitors shall be combined with a corrosion inhibitor. Frost inhibitors should not be mixed
onsite and kept in closed containers.
5.4.3 Flow rate
The flow rates and heat losses shall be calculated and documented according to the required cooling
power for every flow path under design cooling load.
Based on these calculations, set values shall be stated and documented for any required hydronic
balancing devices.
5.4.4 Circulation pumps
Cooling systems shall be designed with minimum pressure loss with due regard to the operation and
economy of the system.
Circulation pumps shall be sized and set so that the required flow rates and pressure differences at any
point of the system and in any operating phase are available.
When pumps are selected, it is important to ensure minimum electricity consumption for the operation
and control of pumps.
Pumps shall be controlled automatically based on the water flow and pressure demand of the cooling
system depending on the relevant operation mode. An exception to this requirement are pumps
requiring a constant water flow, e.g. in connection with ventilation cooling surfaces. Control shall not
limit the possibility of obtaining the desired indoor climate or meeting any requirements for minimum
water flow.
Further consideration shall be given to:
— the suitability of the circulation pump for the task;
— characteristic curves and the optimum range of application;
— thermal insulation;
— sound insulation and noise emission;
— vibration decoupling.
5.4.5 Pipework
Pipework shall be designed and sized so that at any point of the system, the flow rate and the pressure
difference required to fulfil the cooling load of the system are achievable.
Condensation on the pipe surface, on the insulation and the insulation material shall be avoided. For
this reason and to minimize energy losses, all pipes, ducts, components etc. of the distribution system
shall be insulated, also those components leading through brackets and breakthroughs (taking into
account fire protection).
Parts involving a risk of condensation shall be placed visibly. Parts in cooling systems involving a
significant risk of leakage shall be placed visibly or in such a way that leaking water is led to a visible
place. When assessing the risk, the nature and number of joints and the suitability of the prescribed
tightness test for detecting leaks shall be taken into account.
Further consideration shall be given to:
— pipe dimension with effects on:
— pressure drop;
— noise transmittance, e.g. due to flow velocity;
— design pressure;
— material selection;
— corrosion prevention (e.g. restriction of oxygen permeability);
— compatibility of individual components;
— pipework routing:
— accessibility (e.g. for installation and maintenance);
— thermal expansion and contraction;
— fixing (suitability for the scope, protection against noise transmittance);
— provision for filling, emptying and venting;
— the use of sleeves when crossing walls;
— fire protection;
— thermal insulation:
— suitability for the scope (e.g. diffusion barrier against water vapour, thickness of insulation);
— compatibility with the pipe material.
5.4.6 Hydronic balancing
All distribution systems and circuits for chilled and cooling water shall be provided with hydronic
balancing capabilities. All distribution systems shall be hydronically balanced prior to commissioning.
The method of balancing shall be specified during the design phase.
5.5 Cooling emission system – coolers
5.5.1 General
Coolers shall be selected and controlled on the basis of the design cooling load. Consideration shall be
given to:
— the design cooling load;
— the system flow temperature;
— thermal comfort in occupied spaces (should be in accordance with EN ISO 7730, where specified);
— the noise level in occupied spaces;
— protection and prevention of damage to the building components (prevention of condensation);
— maintenance requirements, e.g. cleaning and repair;
— compatibility with supply, distribution and control system.
Cooling emission systems with a high thermal inertia, e.g. pipes embedded in concrete, should not be
the only cooler in rooms with rapidly varying internal loads.
5.5.2 Sizing
Coolers shall be sized on a space-by-space basis.
The dimensioning of the devices and their operating parameters, such as temperatures and flow rates,
shall be determined on the basis of the product data sheets of the respective manufacturer.
The design should include consideration of factors that can affect the capacity of the devices for space
cooling and take into account that such effects are often cumulative, e.g. casing, floor coverings or types
of connection.
Depending on the original design parameters, the design may consider an additional allowance on the
capacity, e.g. for systems that are being operated intermittently (e.g. utility locking times in active
cooling mode through heat pumps).
5.5.3 Positioning of coolers
In choosing the location of devices for space cooling, consideration shall be given to the overall effects
upon the control of room temperatures and comfort conditions. Consideration may also be given to
centrally or decentrally arranged devices for mechanical ventilation of the spaces.
Criteria for assessing the thermal environment can be determined with EN ISO 7730.
Coolers shall be placed and designed so that:
— they contribute to a satisfactory thermal indoor climate in the room;
— building and installation elements are not damaged;
— people are not exposed to injury or inconvenience;
— unnecessary use of resources is avoided.
5.5.4 Protection against damage to buildings and installations
Coolers with low surface temperatures shall be designed so as not to cause inconvenience or damage
due to condensation.
This can be done by:
— keeping the surface temperature of the coolers above the dew point;
— draining condensation.
5.5.5 Unnecessary cooling consumption
Coolers shall be placed and incorporated so as to provide minimum cooling to the space they do not
serve.
Embedded coolers such as floor cooling, ceiling cooling, wall cooling, etc. shall be used only where the
building elements, in which they are incorporated, are properly insulated to adjacent spaces. With the
exception of Thermally Activated Building Systems (TABS), surface insulation to adjacent spaces shall
have a thermal heat transfer coefficient U < 0,5 W/m K.
W
5.5.6 Cleaning
Coolers shall be cleanable in situ by a normal standard method. If a standard method is not possible, the
manufacturer shall specify an appropriate method.
5.6 Cooling system controls
5.6.1 General
The information on controls stated in the document exclusively relates to the extraction of heat from
the cooled space (primary and secondary chilled water circuits, see Figure 1). The control functions
listed in this part refer to the control capabilities of the chilled water circuit which, in conjunction with
dynamic hydronic balancing capabilities, are required for optimizing cooling system performance under
partial cooling load operating conditions.
The control of the heat rejection system shall be adapted to the control concept of the chilled water
circuit, so that full load, partial load and start-up behaviour of the chillers are taken into consideration.
The thermal indoor climate shall be controllable in a simple manner, e.g. by using individual room
temperature control in combination with supply temperature control.
The user’s ability to control the thermal indoor climate should be limited if this results in inconvenience
to other users, e.g. thermal discomfort and increased energy consumption.
Requirements for control are the same for mechanical cooling and for free cooling.
5.6.2 Central control
Central control of the chiller flow temperature shall be provided.
If the primary side is separated from the secondary side by, for example, a hydraulic separator, a
separate control is required for the secondary side. In this case, the flow rate on the secondary side shall
be lower than the flow rate through the chiller.
5.6.3 Local temperature control
Coolers shall be equipped with devices for automatic control of cooling emission according to the room
temperature in each room so that the intended thermal indoor climate is obtained, and unnecessary
energy consumption is avoided. At the same time, operation shall be simple for the user.
Room temperature sensors shall be placed so that the measured temperature is representative of the
operative temperature in the occupied zone.
Individual setting of the desired room temperature in each room shall be possible.
Proportional controllers are dimensioned with a proportional band not exceeding 2 °C under stationary
conditions.
The controller is designed to ensure that the desired tolerances are achieved with a fairly short settling
time. Change of outdoor climate or additional heat shall not require a change in the setting values of the
controller.
There shall be a suitable dead band between heating and cooling in the individual rooms so as to avoid
simultaneous heating and cooling and repeated shift between heating and cooling.
5.6.4 Zone control
A zone control is used to control different devices for space cooling with similar operating parameters.
If a zone control is used, a corresponding hydraulic distribution network shall be provided.
5.6.5 Supply temperature control
Central cooling systems shall be provided with automatic control of the supply temperature. Control of
the supply temperature shall be based on the room or subsystem, e.g. ventilation cooling surface, which
currently requires the lowest supply temperature. Control of the supply temperature shall not be based
on one particular room or subsystem in systems serving multiple rooms or subsystems.
When using embedded cooling terminals or chilled beams, the supply temperature control shall ensure
that condensation is not formed in the coolers and that the heat loss from the distribution system is
limited to the largest possible extent.
The controller may be combined with compensation in relation to the return temperature or the
temperature increase over the system.
In case of different requirements for supply temperature in the various parts of the building or the
system, the system shall be divided into separate zones with individual control of the supply
temperature. In large buildings the system is divided according to the orientation of the façades and
compensation for the solar radiation on the façade.
One zone with common supply temperature control shall only comprise coolers with the same design
supply temperature.
In systems also used for process cooling of e.g. servers or equipment, the supply temperature control
may be omitted if the design output to the ordinary space cooling is below 70 % of the overall design
output of the system for comfort reasons, and there is a requirement for consta
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