prEN 15665

SLOVENSKI STANDARD
01-marec-2025
Prezračevanje stavb - Prezračevalni sistemi v stanovanjskih stavbah -
Projektiranje
Ventilation for buildings - Ventilation systems in residential buildings - Design
Lüftung von Gebäuden - Lüftungssysteme in Wohngebäuden - Design
Ventilation des bâtiments - Systèmes de ventilation dans les bâtiments résidentiels -
Conception
Ta slovenski standard je istoveten z: prEN 15665
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.

DRAFT
EUROPEAN STANDARD
NORME EUROPÉENNE
EUROPÄISCHE NORM
January 2025
ICS 91.140.30 Will supersede CEN/TR 14788:2006, EN 15665:2009
English Version
Ventilation for buildings - Ventilation systems in
residential buildings - Design
Ventilation des bâtiments - Systèmes de ventilation Lüftung von Gebäuden - Lüftungssysteme in
dans les bâtiments résidentiels - Conception Wohngebäuden - Design
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee
CEN/TC 156.
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, 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.
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: Rue de la Science 23, B-1040 Brussels
© 2025 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 15665:2025 E
worldwide for CEN national Members.

Contents Page
European foreword . 4
Introduction . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Abbreviated terms . 9
5 Limitation of the use of options and technical solutions . 10
6 Main purpose and other design aspects of ventilation . 10
6.1 Main purpose of ventilation . 10
6.2 Other design aspects related to ventilation. 11
6.2.1 Energy use . 11
6.2.2 Acoustics . 11
6.2.3 Draught . 11
6.2.4 Outdoor pollutants . 11
6.2.5 Operation, maintenance and cleaning . 12
7 Technical aspects of a ventilation system . 12
7.1 General . 12
7.2 Ventilation strategy (ventilation organization plan) . 12
7.3 Operating principle . 17
7.3.1 Mechanical ventilation . 17
7.3.2 Natural ventilation . 18
7.3.3 Hybrid ventilation . 18
7.4 Control equipment . 19
7.5 Building airtightness . 21
8 Primary ventilation requirements and design approaches . 21
8.1 General . 21
8.2 Expression of primary ventilation requirements . 22
8.3 Performance-based approach . 23
8.4 Prescriptive approach . 24
9 Design steps for the performance-based approach . 25
9.1 General . 25
9.2 Design of a ventilation system in a specific building . 25
9.3 Design of ventilation installation package . 26
10 Design steps for the prescriptive approach. 27
11 Performance assessment method . 27
11.1 General approach . 27
11.2 Primary ventilation requirements and performance indicators . 28
11.2.1 Primary ventilation requirements . 28
11.2.2 Air flow rate related performance indicators . 28
11.2.3 IAQ related performance indicators . 28
11.3 Calculation model and assumptions . 29
11.3.1 Calculation model . 29
11.3.2 Input data for the calculation model . 30
11.4 Aggregation of the calculation results . 30
12 Documentation of specifications and layout . 30
Annex A (informative) Template for the limitation of the use of options and technical
solutions at national level . 31
Annex B (informative) Examples of primary ventilation requirements based on air flow
rates and of prescriptive requirements . 38
Annex C (informative) Comparison of the performance-based and the prescriptive
approach . 46
Annex D (informative) Design aspects specific to mechanical ventilation . 48
Annex E (informative) Design aspects specific to natural ventilation . 53
Annex F (informative) Design aspects specific to hybrid ventilation . 58
Annex G (informative) Control equipment . 64
Annex H (informative) Typical types of performance indicators to be used in the
performance-based approach . 67
Annex I (informative) Specifying design assumptions . 71
Annex J (informative) Usage agreement for operation . 75
Bibliography . 77

European foreword
This document (prEN 15665:2024) has been prepared by Technical Committee CEN/TC 156 “Ventilation
for buildings”, the secretariat of which is held by BSI.
This document is currently submitted to the CEN Enquiry.
This document will supersede EN 15665:2009 and CEN/TR 14788:2006.
In addition to a number of editorial revisions, the following main changes have been made:
— a distinction between “prescriptive approach” and “performance-based approach” (based on the
performance assessment method) has been made;
— a (normative) National Annex A, with open templates for the prescriptive approach and
performance-based approach has been added.
Introduction
The main role of ventilation is to replace the air in order to ensure an acceptable indoor air quality. It also
helps to maintain the integrity of the building and improve the comfort of its occupants by controlling the
humidity to avoid too low and too high humidity. But this document only focuses on indoor air quality.
Ventilation dilutes natural background pollutants such as substances emitted by furnishings, building
materials and cleaning products used in the building, odours, metabolic CO and water vapour.
Ventilation also dilutes specific pollutants from identifiable local sources such as toilet odours, water
vapour from the kitchen or bathroom.
Design of ventilation systems commonly considers other aspects like energy use, acoustics, draught,
outdoor pollutants and cleaning and maintenance, though these are not covered in detail in this
document.
There are both risks for the occupants and the building in terms of IAQ, specifically of relative humidity
(one indicator for indoor air quality and thermal comfort).
IAQ can be controlled by the following means: source control, ventilation, and potentially air filtration or
air cleaning.
This document is intended to support any regulation or standard at national level by giving guidance to
those with responsibility for producing requirements and standards for residential ventilation systems.
It includes a national annex template for fixing choices and setting primary ventilation requirements at
national level. A filled in national annex, is directly usable by the designer for precise requirements on
design of a ventilation system.
This document has a link to EN 16798-1 and EN 16798-7, in which basic information on possible indoor
air quality requirements can be found, and gives information on how to calculate air flow rates in
buildings.
1 Scope
This document provides guidance for the design of ventilation systems for basic ventilation in residential
buildings to achieve an acceptable indoor air quality. It gives two approaches:
— prescriptive approach;
— performance-based approach.
This document establishes guidelines for the usage of both the prescriptive and performance-based
approaches. This document specifies performance indicators that can be used with the performance-
based approach.
This document partly covers intensive ventilation for indoor air quality purposes.
This document concerns residential buildings but primarily focuses on dwellings (flats, apartments, and
houses) and is also applicable to parts of other types of residential buildings.
This document is applicable to, but not limited to:
— mechanical ventilation;
— natural ventilation;
— hybrid ventilation.
This document does not apply to:
— dilution of tobacco smoke or radon and other soil gases;
— ventilation of garages, roof voids, sub-floor voids, wall cavities and other spaces in the structure,
under, over or around the living space;
— providing air for combustion appliances;
— air cleaning (e.g. portable stand-alone air cleaners to clean the indoor air);
— air humidification or de-humidification;
— thermal comfort in regard to overheating aspects.
This document does not deal with the assessment of energy performance of buildings.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for the 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
ventilation
air replacement by purpose-provided means
Note 1 to entry: “purpose-provided means” implies design and characterizes knowledge of main characteristics
allowing assessment so that requirements on ventilation are fulfilled.
Note 2 to entry: Ventilation can be combined with air treatment.
3.2
basic ventilation
ventilation to achieve primary ventilation requirements under normal circumstances
3.3
intensive ventilation
ventilation at increased air replacement rate for a specific purpose limited in time
3.4
natural ventilation
ventilation whose operating principle is based solely on the effect of wind and the stack effect
Note 1 to entry: Open windows can be used for natural ventilation, if they are purpose-provided.
3.5
mechanical ventilation
ventilation whose operating principle is based solely on the operation of fans
3.6
hybrid ventilation
ventilation whose operating principle is based on the combination or alternation of natural ventilation
and mechanical ventilation
3.7
airing
air replacement by means that are not purpose-provided
Note 1 to entry: Usually done through manual opening of doors or windows or both.
3.8
stack effect
pressure difference caused by the difference in density between indoor air and outdoor air due to their
temperature difference
Note 1 to entry: With increased height difference between openings and temperature difference between indoor
and outdoor air, the stack effect flow increases.
3.9
habitable room
main room
room dedicated to living, sleeping or dining purpose
EXAMPLE living room, bedroom, dining room, home office
3.10
service room
wet room
room dedicated to cooking, washing, defecating or urinating purpose
EXAMPLE kitchen, bathroom, laundry, toilet
3.11
circulation room
room with no specific allocation except circulation within the building
EXAMPLE corridor, hall, stairwell
3.12
vent
opening in the building shell intended for passage of air
EXAMPLE externally mounted air transfer device, intake air terminal device, roof outlet or window designed
for the purpose of air replacement
3.13
intake vent
vent through which air is taken from outside the building
3.14
exhaust vent
vent through which air is discharged to outside the building
3.15
residential
relating to where people live
3.16
primary ventilation requirement
requirement aiming to quantify a level of indoor air quality to be achieved or an amount of air
replacement to be achieved
3.17
descriptive requirement
requirement in the form of a specified technical solution
EXAMPLE minimum opening area
3.18
performance-based requirement
requirement in the form of a goal to be achieved
3.19
IAQ parameter
quantity that enables the characterization of indoor air quality, in whole or in part
EXAMPLE CO concentration
3.20
performance indicator
quantity that indicates a performance
EXAMPLE Number of hours under or above a humidity threshold.
3.21
supply air
air from a ventilation installation or air conditioning installation entering a room
3.22
transferred air
air which passes from a room to another room
Note 1 to entry: Transferred air is extract air from one room and supply air for the other room.
3.23
extract air
air from a room entering a ventilation installation or air conditioning installation
3.24
ventilation system
combination of a ventilation installation and the enclosure it serves
3.25
package
group of objects, plans, or arrangements that are related and offered as a unit
3.26
ventilation system package
ventilation installation package
package intended for the realisation of a ventilation installation
Note 1 to entry: An installation ready package.
3.27
exposure
concentration of a given substance a person is exposed to
3.28
cumulative exposure
exposure that a specific person experiences over a given period of time
4 Abbreviated terms
For the purposes of this document, the abbreviations given in Table 1 apply.
Table 1 — Abbreviated terms
Abbreviated terms Designation
ACH Air Change Rate
BAC Building Automation and Control
CO Carbon dioxide
Abbreviated terms Designation
EMATD Externally Mounted Air Transfer Devices
EN European Standard
IAQ Indoor Air Quality
PM Particulate Matter
RH Relative Humidity
STR Ventilation strategy
SVOC's Semi-Volatile Organic Compounds
VOC's Volatile organic compounds

5 Limitation of the use of options and technical solutions
This document describes various options and technical solutions. Limitations of the use of these options
and technical solutions may be provided in a national annex. If a national annex is created it shall be done
in accordance with the template given in Annex A.
Examples of filled in templates are given in Annex B.
NOTE The reason for this possible limitation is that not all options and technical solutions are relevant for all
national conditions (e.g. climatic conditions).
These options and technical solutions concern:
— the ventilation strategies, operating principles and controlling equipment (see Clause 7);
— the primary ventilation requirements (see Clause 8);
— the choice of the performance-based approach (see Clause 8 and Clause 9) or the prescriptive
approach (see Clause 8 and Clause 10) or both approaches;
— the performance assessment method (see Clause 11).
6 Main purpose and other design aspects of ventilation
6.1 Main purpose of ventilation
The main purpose of ventilation is to achieve an acceptable indoor air quality (basic ventilation) with
relevant IAQ parameters (e.g. CO , VOC's, water vapour).
Ventilation is also an important mean of controlling humidity in a building in order to reduce the risk of
condensation on building walls and materials.
Basic ventilation covers normal circumstances. Ventilation can sometimes be increased for a specific
purpose for a given period of time (intensive ventilation). This can be done whatever the operating
principle (mechanical ventilation, natural ventilation or hybrid ventilation).
Airing is another possible option to supplement a ventilation system for such increase of the air
replacement rate.
However, ventilation can have consequences, possibly negative, such as energy use or unwanted draught.
The main possible consequences of ventilation are listed in 6.2 and are not further detailed in this
document. The design of a ventilation system should take these consequences into account to minimize
their possible negative effects.
6.2 Other design aspects related to ventilation
6.2.1 Energy use
During the design of the ventilation system, the following possible aspects of energy use related to
ventilation should be considered:
— the energy use for heating and cooling;
— the energy use for the transport of the ventilation air (fan electrical energy);
— the energy use for the control equipment;
— the energy use for humidification or de-humidification.
When designing a ventilation system, IAQ should be considered together with the energy implications,
although the assessment of energy performance of buildings is not dealt with in this document.
NOTE EN 16798-5-1, EN 16798-5-2 and CEN/TR 16798-6 are about calculation of energy requirements for
mechanical and air-conditioning systems.
Some aspects of the energy use due to ventilation can also be an output of the performance assessment
method (see Clause 11).
6.2.2 Acoustics
During the design of the ventilation system, the following possible aspects of acoustics should be
considered:
— the noise from the inside environment;
— the noise from the outside environment;
— the noise generated indoors and outdoors by the ventilation system itself (e.g. fans, dampers, air
flows and actuators).
The noise caused by the ventilation system can cause nuisance to the occupants and hence influence their
use of the ventilation system.
NOTE EN 16798-1 provides basic information on possible acoustic criteria, but acoustic criteria can also be
found, e.g. in national legislation.
6.2.3 Draught
During the design of the ventilation system, unwanted draught possibly caused by ventilation air flows
should be considered.
This draught can cause nuisance to the occupants and hence influence their use of the ventilation system.
NOTE EN ISO 7730 and EN 16798-1 provides basic information on possible criteria on draught.
6.2.4 Outdoor pollutants
During the design of the ventilation system, the outdoor air quality should be considered.
Technical solutions to handle outdoor pollutants include, for example, proper placement of intake vents,
filtration, demand controlled ventilation based on outdoor air quality or air cleaning.
NOTE For mechanical ventilation systems, information on filtration and its classification is available in
EN 16798-3.
6.2.5 Operation, maintenance and cleaning
Cleaning and maintenance of the ventilation installation are necessary to maintain the performance of
the ventilation system over time.
During the design of the ventilation system, the following aspects should be considered:
— accessibility to the components to be replaced (e.g. filters);
— accessibility to the components to be cleaned (e.g. ducts, fans, air transfer devices or air terminal
devices);
The use of filters can also help to protect the ventilation system against fouling.
NOTE 1 Information about requirements for ductwork components to facilitate maintenance of ductwork
systems is available in EN 12097.
NOTE 2 Information about cleanliness of ventilation system is available in EN 15780.
NOTE 3 For design and operation it is possible that the relevant usage of the rooms, and the requirements, in
particular, are done in writing in a usage agreement. Such a usage agreement is often between the building owner,
designer and user. An example of a usage agreement during operation is given in Annex J.
7 Technical aspects of a ventilation system
7.1 General
Ventilation strategy, controlling system and operating principle are technical aspects that can be used to
define a ventilation system. These aspects are combined together during the design of the ventilation
system (see Clause 9 and Clause 10).
7.2 Ventilation strategy (ventilation organization plan)
The ventilation strategy is a detailed plan that defines the path of air within a building.
The ventilation strategy is usually based on a distinction between habitable rooms, circulation rooms and
service rooms. It may however also include other rooms. These other rooms are treated like habitable
rooms or service rooms or treated separately depending on the expected generated indoor pollution.
Examples of other rooms are storage room, dressing room, home gym room and garage.
One of the main principles of a good ventilation strategy is to avoid spreading of pollutants within the
building. Air from service rooms is therefore not suitable for recirculation or transfer to other rooms.
Different ventilation strategies can have different impact on the energy use (see 6.2.1); transferring air
from one room to another is therefore often considered.
Examples of ventilation strategies are given in Table 2 and Figures 1 to 7. Additional ventilation
strategies may be defined in a national Annex A.
Table 2 — Examples of ventilation strategies
Ventilation strategy Description
STR
Supply of air in all habitable rooms and service rooms
STR 1 Extraction of air from all habitable rooms and service rooms
There is no provision for ventilation of circulation rooms
Supply of air in all habitable rooms
Transfer of air in all circulation rooms from habitable rooms
STR 2
Transfer of air in all service rooms from circulation rooms (or habitable rooms
if not connected to circulation room)
Extraction of air from all service rooms
Supply of air in all habitable rooms
Transfer of air in all circulation rooms from habitable rooms
Transfer of air in all service rooms from circulation rooms (or habitable rooms
STR 3
if not connected to circulation room)
Extraction of air from all service rooms
Extraction of air from some or all habitable rooms
Supply of air in circulation rooms
Transfer of air in all habitable rooms from circulation rooms
Transfer of air in all service rooms from circulation rooms (or habitable rooms
STR 4
if not connected to circulation room)
Extraction of air from all habitable rooms (except those that transfer air to a
service room) and service rooms
Supply of air in some habitable rooms (HR1) (e.g. rooms mainly occupied
during the night)
Transfer of air in all circulation rooms from these habitable rooms
Transfer of air in all other habitable rooms (HR2) (e.g. rooms mainly occupied
during the day) from circulation rooms (or first mentioned habitable rooms
STR 5
(HR1) if not connected to circulation room)
Transfer of air in all service rooms from last mentioned habitable rooms (HR2)
or from circulation rooms
Extraction of air from all service rooms and from last mentioned habitable
rooms not connected to a service room
Supply of air to some of the habitable rooms and some of the service rooms
Extraction of air from the other habitable rooms and other service rooms
STR 6
Transfer of air in all circulation rooms from rooms with supply of air
Transfer of air in all rooms with extraction of air from circulation rooms (or
from rooms with supply of air if not connected to a circulation room)
Supply of air in all habitable rooms and service rooms.
Extraction of air from all habitable rooms and service rooms.
STR 7
Transfer of air in circulation rooms from habitable rooms.
Transfer of air from circulation rooms in habitable rooms.

Key
1 habitable room
2 circulation room
3 service room
Figure 1 — Illustration of ventilation strategy STR 1

Key
1 habitable room
2 circulation room
3 service room
Figure 2 — Illustration of ventilation strategy STR 2
Key
1 habitable room
2 circulation room
3 service room
Figure 3 — Illustration of ventilation strategy STR 3

Key
1 habitable room
2 circulation room
3 service room
Figure 4 — Illustration of ventilation strategy STR 4
Key
1 habitable room
2 circulation room
3 service room
Figure 5 — Illustration of ventilation strategy STR 5

Key
a habitable room or service room
b circulation room
Figure 6 — Illustration of ventilation strategy STR 6
Key
1 habitable room
2 circulation room
3 service room
Figure 7 — Illustration of ventilation strategy STR 7
7.3 Operating principle
7.3.1 Mechanical ventilation
Mechanical ventilation can be subdivided into three different types:
— fan assisted bidirectional ventilation that employs fans in both the supply air and extract air sides;
— fan assisted exhaust ventilation that employs fans in the extract air side only;
— fan assisted supply ventilation that employs fans in the supply air side only.
With fan assisted exhaust ventilation, fans in the extract air side induce underpressure inside the
building. This underpressure enables air to enter the building through intake vents, e.g. externally
mounted air transfer devices.
With fan assisted supply ventilation, fans in the supply air side induce overpressure inside the building.
This overpressure enables air to flow out of the building through exhaust vents, e.g. extract air terminal
devices, cowls or externally mounted air transfer devices.
Stack effect and wind are not taken into account in the design of mechanical ventilation systems but can
have an impact on the actual performance of the system.
NOTE 1 For externally mounted air transfer devices see EN 13141-1.
Transfer of air within the building can be realized with internally mounted air transfer devices, door
undercuts or fan and possibly a ductwork.
Depending on the number and position of fans, a distinction can be made between:
— decentralized ventilation system (individual fans for each served room);
— centralized ventilation system at the level of the dwelling (common fans for one dwelling);
— centralized ventilation system at the level of the building (common fans for several flats or
apartments in a building).
The fans and the possible ductworks are selected and sized to realize the design air flow rate in each room
served by the ventilation system.
NOTE 2 Pressure drop calculation that is necessary for selecting and sizing fans and ductwork is out of the scope
of this document.
NOTE 3 For design guidance on typical mechanical ventilation systems (including possibilities for designers to
organize the ventilation strategies in terms of air distribution from room to room), see Annex D.
7.3.2 Natural ventilation
The operating principle of natural ventilation is based solely on the effect of wind and the stack effect.
Pressure differences generated by the wind and stack effect can vary in time because of variation of wind
speed or direction and variation of temperature difference between inside and outside. This can cause
variation of air flow rate or air flow direction. These effects can spread polluted air from one room to
another and can decrease the air flow rate through intake vents or exhaust vents in certain rooms, if not
controlled correctly.
The pressure differences can be sufficient to provide air flow rates in the room under certain conditions.
It depends on the position of vents in the building envelope and on the building layout (number of façades,
number of floors, height difference between supply and exhaust, etc.). Intentional design of ventilation
openings for natural ventilation should be carried out by including the building itself.
Natural ventilation can be subdivided into three different types:
— single-sided ventilation that relies on one or several openings located in the same façades or roof of
a building or room;
— stack ventilation (also called “thermal buoyancy” or “stack effect”) that relies on openings located at
different heights in the façades or roof of a building or room;
— cross ventilation that relies on openings located on different façades or roof of a building or room.
NOTE For design guidance on typical natural ventilation systems, see Annex E.
7.3.3 Hybrid ventilation
The operating principle of hybrid ventilation is based on the combination of natural and mechanical
ventilation. The basic control of this combination can be either alternating or simultaneous. It can consist
of a basic system and a supporting system. The basic system is the part of the hybrid ventilation that
provides the majority of the ventilation in normal operation. A basic mechanical ventilation and a basic
natural ventilation system, without splitting into “majority” is also possible. This classification can be
based, for example, on a frequently occurring operating case (operating time, outdoor conditions, etc.).
The basic system shall be designed for this case. In planning, the basic system is typically designed first.
In the case of alternative mechanical/natural ventilation, the system in use is the basic system.
Hybrid ventilation can be subdivided into three basic hybrid operation principles and two different
controlling strategies.
Basic hybrid operating principles:
— basic system natural ventilation, supported by mechanical ventilation, (e.g. fan assisted natural
ventilation);
— basic system mechanical ventilation, supported by natural ventilation, (e.g. stack and wind assisted
mechanical ventilation);
— two basic systems comprising of mechanical and natural ventilation, (e.g. basic system operating in
heating season is mechanical ventilation, basic system operating in cooling season is natural
ventilation).
Basic control:
— alternatively natural and mechanical ventilation:
— hybrid ventilation that is based on the alternation of fully autonomous natural ventilation and
mechanical ventilation depending on actual need;
— simultaneous natural and mechanical ventilation:
— hybrid ventilation that is based on simultaneous operation of fully autonomous natural
ventilation and mechanical ventilation.
NOTE For design guidance on typical hybrid ventilation systems, see Annex F.
7.4 Control equipment
Control equipment of a ventilation system enables to vary the air flow rate within the building.
Justification for controlling a ventilation system is:
— to adapt the air flow rate according to the ventilation needs;
— to limit the ingress of pollutants during outdoors pollution peaks.
Potential benefits of controlling a ventilation system can be, e.g.:
— to improve the indoor air quality;
— to control lower and upper bounds of relative humidity;
— to achieve low energy use in the heating season or cooling season;
— to reduce energy use of fans;
— to limit the heating-up power in intermittently heated spaces.
There are typical controls that can be applied:
— no control: the ventilation system runs constantly with fixed settings;
— manual control: the ventilation system runs in manual operation;
— time control: the ventilation system runs according to a schedule;
— presence control: the ventilation system runs according to the presence of people whatever their
number;
— demand control: the ventilation system runs according to the measure of the actual value of one or
several variables supposed to reflect the ventilation needs. In practice, demand control needs one or
several measuring elements.
More information about control equipment is given in Annex G.
Manual control of ventilation systems is not always efficient because human operators (people) are not
fully able to differentiate between acceptable and not-acceptable indoor air quality on their own.
A distinction, based on the extent to which ventilation of the rooms is controlled in common (mutually),
can be made between:
— central control: common control of the air flow rate for all rooms;
— zonal control: common control of the air flow rate for all rooms of a zone and control of the air flow
rate in two or more zones separately, at least one zone is made of more than one room;
— local control: control of the air flow rate for all rooms separately.
Description of all zones with a detailed list of rooms is needed in case of zonal control.
EXAMPLE Zonal control can be based, e.g. on a repartition of rooms between a “day zone” (e.g. living room,
dining room, home office) and a “night zone” (e.g. bedrooms).
NOTE Information on possible controls criteria, which have an impact on energy declaration and functional
range for mechanical ventilation systems, are listed in EN 13142:2021, Annex A.
There is a large variety of possible combinations of control extents and types of controller input variables,
see Table 3.
Based on similar controller input variables, the potential for air flow rate reduction (compared with a
constant air flow rate situation) is higher with local control than with zonal control or central control.
Table 3 — Possible combinations of control extents and types of controller input variables
Type of controller input  Control extent
variables
Local control Zonal control Central control
Single-room related Applicable Applicable Applicable
controller input variables
It needs at least one It needs at least one
controller input controller input
variable per room variable per zone
Multi-room related Not applicable Applicable Applicable
controller input variables
It needs at least one
(none of them covering
controller input
rooms across different
variable per zone
zones)
Multi-room related Not applicable Not applicable Applicable
controller input variables (at
least one of them covering
rooms across different zones
or covering all rooms
together)
Typical application of control of ventilation systems in dwellings is given in Table 4 as a function of the
room type. The selection of the most relevant variables depends on the different sources of pollutants of
concern in the considered room or set of rooms. This is given as an example only and does not prevent
any other application.
Table 4 — Typical application of control of ventilation installations in dwellings
(except manual control)
Room Control Variable
Whole dwelling Time control —
Whole zone
Demand control CO concentration
Air humidity
Kitchen Presence control —
Demand control CO concentration
Air humidity
Bathroom Demand control Air humidity
Laundry Demand control Air humidity
Toilet Presence control —
Demand control Volatile organic compounds
(VOC’s) concentration
CO concentration
Living room, dining room, home Presence control —
office
Demand control CO concentration
Air humidity
Bedroom Time control —
Presence control —
Demand control CO concentration
Air humidity
Classification of controls may be used for the whole ventilation installation or for different parts of it (e.g.
supply side and extraction side).
7.5 Building airtightness
Air leakages in the building envelope as well as the wind and stack effect can disrupt the operation of
certain ventilation systems by modifying the pressure differences between rooms themselves or between
inside and outside the building. These effects can spread polluted air from one room to another (by
affecting the path of air foreseen in the ventilation strategy) and can decrease the air flow rate through
intake vents or exhaust vents in certain rooms.
The magnitude of disruption can be limited by the ventilation system design or thanks to a sufficiently
good airtightness of the building.
The application of certain ventilation systems may be limited to a minimum level of building airtightness.
8 Primary ventilation requirements and design approaches
8.1 General
This document describes two design approaches allowing to set a framework for designing a ventilation
system, that is either the prescriptive approach or the performance-based approach. Each of these design
approaches consists of several elements, among others additional requirements and conditions of use
that may be given in a national Annex A.
The design approach also involves different target groups, such as national standardization bodies,
manufacturers, or designers (see Clause 8). These two design approaches are illustrated in Figure 8 and
Figure 9.
For further information on comparison between the two design approaches, see Annex C.
8.2 Expression of primary ventilation requirements
Designing a ventilation system is based on primary ventilation requirements. This document does not set
the primary ventilation requirements but gives guida
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