FprCEN/TR 16244

SLOVENSKI STANDARD
01-maj-2011
3UH]UDþHYDQMH]DEROQLãQLFH
Ventilation for hospitals
Lüftung für Krankenhäuser
Ventilation des hôpitaux
Ta slovenski standard je istoveten z: FprCEN/TR 16244
ICS:
91.040.10 Javne stavbe Public buildings
91.140.30 3UH]UDþHYDOQLLQNOLPDWVNL Ventilation and air-
VLVWHPL conditioning
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

TECHNICAL REPORT
FINAL DRAFT
RAPPORT TECHNIQUE
TECHNISCHER BERICHT
March 2011
ICS 91.140.30; 91.040.10
English Version
Ventilation for hospitals
Ventilation des hôpitaux Lüftung für Krankenhäuser

This draft Technical Report is submitted to CEN members for Technical Committee Approval. It has been drawn up by the Technical
Committee CEN/TC 156.
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, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland 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 Technical Report. It is distributed for review and comments. It is subject to change without notice and
shall not be referred to as a Technical Report.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2011 CEN All rights of exploitation in any form and by any means reserved Ref. No. FprCEN/TR 16244:2011: E
worldwide for CEN national Members.

Contents Page
Foreword .3
1 Scope .4
2 Normative references .4
3 Terms, definitions, and abbreviations .4
4 Abbreviated terms .7
5 General requirements .7
6 Classification of rooms used for medical purposes (room classes) and ventilation
concepts .8
7 Requirements for ventilation and air-conditioning components . 14
8 System qualification . 40
9 Acceptance tests . 42
10 Periodic tests . 46
11 Requirement for the technical documentation . 48
Annex A (informative) Planning, construction, and operation . 50
A.1 General . 50
A.2 Project phases and objectives . 50
A.3 Analysis . 51
A.4 Project aims . 51
A.5 Planning . 53
A.6 Implementation . 54
A.7 Operation . 55
Annex B (informative) Examples of air flow distribution concepts (specifically for operating and
isolation rooms) . 58
B.1 Example of the symmetric arrangement of circulating air and extract air terminal devices
in operating rooms . 58
Annex C (normative) Qualification of rooms of room class H1. 60
C.1 Flow visualisation for room class H1a – General . 60
C.2 System test / Pre-qualification for room class H1a – Pre-qualification of LTF systems
(room with air duct and lighting system) in operating rooms of room class H1a . 61
C.3 Acceptance test following the procedure for measuring the turbulence intensity in room
class H1a . 67
C.4 Acceptance test by determining the protective effect for room class H1a . 70
C.5 Acceptance test of class H1a rooms in accordance with EN ISO 14644 . 76
Annex D (normative) Microbiological tests . 80
D.1 General . 80
D.2 Procedure . 80
D.3 Requirements . 80
D.4 Evaluation . 81
Annex E (informative) Maintenance plan for the VAC system . 82
Bibliography . 86

Foreword
This document (FprCEN/TR 16244:2011) 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 Technical Committee Approval.

1 Scope
This Technical Report applies to health service buildings and rooms used for medical examinations,
treatments and interventions to be carried out on people as well as to rooms directly connected to those
rooms by doors, corridors/hallways, etc.
It establishes rules for planning, construction, qualification, and operation of ventilation and air-conditioning
(VAC) systems and components intended to be used in:
 hospitals buildings;
 day hospitals;
 physician’s practices with intervention rooms;
 outpatient surgery centres / facilities / ambulatories;
 dialysis centres;
 convalescent homes, rehabilitation facilities, sanatoria;
 long-term care facilities, senior retirement and nursing homes;
 facilities for internal and external (service) units for the processing of medical devices / sterilization areas.
In addition to that, air hygienically relevant guidance is given regarding building services / heating installations.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated referen-
ces, only the edition cited applies. For undated references, the latest edition of the referenced document
(including any amendments) applies.
EN 12792:2003, Ventilation for buildings ― Symbols, terminology and graphical symbols
3 Terms, definitions, and abbreviations
For the purposes of this document, the terms and definitions given in EN 12792:2003 and the following (in
alphabetical order) apply.
3.1
air lock
room located between two rooms of different room classes
NOTE It is used to reduce transmission of aerobic infectious agents between rooms of different classes. The air lock
is supplied with air as well as vented by mechanical means and can be operated with overpressure or underpressure.
Alternatively, air locks that should be passed before entering a class H1b operating room can also be supplied with air by
over-flow from the operating room.
3.2
hygienist
according to this Technical Report, a medical specialist for hygiene pursuant to the advanced training
regulations of the federal states with special expertise in the fields of ventilation technology or an expert
working in an agency for the fulfilment of hygiene-related tasks, each with special knowledge and experience
in the field of ventilation and hospital hygiene (also called hygiene expert / specialist for hygiene / hospital
hygienist in different countries, function needs to be described)
3.3
interventions
as distinct from operations
NOTE This differentiation is made in correspondence with the annex to the attachment accompanying numbers 5.1
and 4.3.3 of the requirements for hygiene in ambulant surgery (Anforderungen der Hygiene beim ambulanten Operieren in
Krankenhaus und Praxis) published by the Robert Koch Institute, Berlin.
3.4
servicing
includes measures for determining and assessing the actual state of a system’s technical means (inspection)
as well as for maintaining the nominal condition of a system’s technical means (maintenance)
3.5
resistant to disinfectants
according to this TR, ventilation and air-conditioning components and products are considered to be resistant
to disinfectants if they are able to withstand a long-term application of disinfectants and disinfecting methods
NOTE The only disinfectants used are those included in the list published by the Robert Koch Institute (RKI) or the
Association for Applied Hygiene (Verbund für angewandte Hygiene e.V., VAH), respectively.
3.6
repair
measures for restoring the nominal condition of a system’s technical means
3.7
room classes
classes assigned to rooms used for medical purposes
3.8
protective isolation / sterile care
patients with a risk of infection
3.9
source isolation / infectious patients
patients with infection
3.10
VAC-central-plant
ventilation and air-conditioning system containing all components (sound attenuators, dampers, heat
exchangers etc.) installed inside a central plant in order to facilitate cleaning and maintenance
3.11 Qualifications
3.11.1
system qualification
qualification of systems that includes the partial steps installation qualification, function qualification, and per-
formance qualification
NOTE Each subsequent partial step should be started only after completing the improvements required and
successfully passing the re-checks for the previous partial step.
3.11.2
installation qualification
systematic sequence of inspections, measurements, and tests (as well as adjustments, if necessary) carried
out in order to ensure the compliance of all system parts with the planning requirements
3.11.3
function qualification
series of tests and measurements carried out in order to ensure the correct functioning of all system parts
3.11.4
performance qualification
tests and measurements proving that the entire system achieves the operating state agreed
3.11.5
planning qualification
planning ends with a qualification intended to demonstrate the compliance of the execution planning with the
requirements defined in the task formulation (performance specifications)
3.12 Operating-rooms
3.12.1
low turbulence flow (LTF) plenum
supply air plenum with a vertical air outlet used to obtain a low-turbulence displacement flow (Tu ≤ 20 %) in
the entire protected area
3.12.2
turbulence level Tu
measure for the fluctuations of the air velocity in relation to its mean value (relative standard deviation), in %
NOTE A flow with a turbulence level of less than 5 % is designated as “laminar” and “low-turbulence” between 5 %
and 20 %, respectively, whereas a flow with a turbulence level of more than 20 % is called “turbulent”.
3.13
overpressure / underpressure
positive or negative air balance
3.14
positioning analysis
Identification of floor space required specific for clinic of the protected area for which itself approximately 9 m²
(e.g. 3 m × 3 m) have proved themselves as a standard size in the international operation practise
NOTE The standard construction situations are to be shown for the operating field, the tables for exposed sterile
instruments and materials and the operating room staff wearing sterile clothing. The aforementioned potential disturbing
factors should be considered very carefully in cooperation with the hygienist and the VAC-consultant taking into account
that in any case the protection effect needs to be demonstrated.
3.15
pre-qualification
pre-qualification is carried out in order to assess the structuring and technical design of operating rooms with
LTF systems as a system test
NOTE It is carried out in connection with all the relevant boundary conditions of the operating room under the
planned thermal loads (e.g. persons, equipment, basic heating) as regards equipment (e.g. associated operating lamps,
special flow stabilisers) and space.
3.16
protected area / fields operating-rooms
includes, in addition to the operating field/wound, the sterile covers for the patient, the tables for sterile instru-
ments and materials as well as the operating room staff wearing sterile clothing
4 Abbreviated terms
ETA Extract air
EHA Exhaust air
BA Building automation
BIU Building instrumentation and control
HEPA High Efficiency Particulate Air filter, air filter group in accordance with EN 1822-1
CFU Colony forming unit
MIS Minimally invasive surgery
UEPF Upper edge of prefabricated floor
OR Operating room
QM Quality management
VAC (system) Ventilation and air-conditioning (system)
LTF Low-turbulence flow
Tu Turbulence degree/level
RKI Robert Koch Institute, Berlin
5 General requirements
5.1 Basic principles
In addition to good training, organization, and discipline of the medical and technical staff, scrupulous attention
to hygiene calls for the hospital and its facilities to be designed and constructed accordingly. This should be
considered in the planning, construction, operation, and servicing of the VAC system.
On account of the great variety of requirements a hygienist is to be involved during the entire planning and
construction process of new buildings, re-buildings, and expansions.
The requirements for ventilation and air-conditioning systems given in this TR are minimum requirements.
Higher requirements are possible, e.g. for medical, operation/organizational or technical reasons.
Any deviation from a standard should be agreed upon between the client, the hygienist, and the VAC-
consultant and be kept on file together with a detailed justification. This agreement should be enclosed when
filing the application for approval of the relevant health care supervisory authority and be brought to the
knowledge of the company installing the VAC system once the approval has been granted.
The need for VAC systems is mainly determined by the following criteria:
 hospital specific indoor air hygiene as contributing to reducing the concentration of microorganisms and
particle charges;
 ensuring the physiology/comfort including the management of thermal loads;
 reduction of the content of harmful, toxic gases and annoying odours;
 compensation for unfavourable external conditions (e.g. highly polluted outdoor air, high humidity loads,
high sound pressure levels outside, strong wind loads in the case of exposed locations (great building
height));
 compensation for unfavourable internal conditions (e.g. unopenable windows, internal rooms, rooms of
great spatial depth, application of radioactive substances).
5.2 Guidance on planning, construction, and operation
In order to take account of the high requirements for planning, construction, and operation of VAC systems in
medical facilities it is required for all the people participating in the project (user, VAC-consultant, installer,
hygienist, building manager, etc.) to be involved in an appropriate manner as early as in the design phase of
the planning process and to have the same information at their disposal.
With project development for the health care services it is important at first to determine the demand based on
current and future obligatory user provisions in the form of a project performance specification-paper.
With interdisciplinary planning projects it is of great importance to ensure that the individual planning and
decision making steps are executed in a strictly structured manner and that they are documented accordingly.
A structured approach is therefore recommended in Annex A.
6 Classification of rooms used for medical purposes (room classes) and ventilation
concepts
6.1 Room classes
Rooms used for medical purposes are divided according to the required low level of germs (hygiene require-
ments) into the following room classes:
 room class H1a (LTF with a protection field for the operating field and instrument tables (≥ 9 m );
 room class H1b (LTF with a reduced protection field (< 9 m ));
 room class H1c (turbulent mixed flow);
 room class H2 (protective isolation, patients with a risk of infection);
 room class H3 (source isolation, infectious patients);
 room class H3a: H-13 extract air filter (e.g. multi-resistant tuberculosis);
 room class H3b: H-13 supply air filter and extract air filter (e.g. Lassa fever);
 room class H3c: e.g. radio-nuclides (see other bodies of rules and regulations);
 room class H4: other rooms used for medical purposes.
Rooms and areas of room classes H1, H2, and H3 should always be equipped with mechanical ventilation
systems.
Rooms and areas of room class H4 should only be equipped with mechanical ventilation systems if require-
ments in accordance with 5.1 apply or if a compensation of the air volume balance is required or if natural
ventilation is not possible.
6.2 Ventilation concepts and requirements
6.2.1 Air filtering
Technical measures can contribute to reduce germ-concentrations in the air. Therefore, the supply air should
be treated by means of filters for suspended matter to be installed.
 room classes H1 and H2: supply air: 3 filtration stages, extract air: 1 filtration stage;
 room classes H3 and H4 supply air: 2 filtration stages, extract air: 1 filtration stage.
For separating particulate contaminations, including microorganisms, a multi-stage supply air filtration is
required equivalent to the following filter classes:
st
 1 filtration stage: filter class F7;
nd
 2 filtration stage: filter class F9;
rd
 3 filtration stage: filter class H13 for suspended matter.
For the extract air from class H3 rooms, it can, in addition, be necessary to install suspended matter and/or
sorption filters.
If, for technical reasons (e.g. to protect heat-recovery systems), a filtration of the extract air is required, then
this should correspond to at least equivalent to F5.
6.2.2 Ventilation concepts
6.2.2.1 Concepts for operating rooms, H1
6.2.2.1.1 General
The objective of all protective measures in connection with surgical interventions is to reduce the risk of post-
operative infections and particle contamination of the wound. This risk is subject to great variation dependent
on the nature of the surgical intervention.
In order to achieve this, measures can be of support such as the consistent application of dynamic shielding of
the protected area by low-turbulence flow (LTF) and of the operating room by directional over-flow into the
adjoining rooms connected by doors. Using these measures prevents contaminations from the surroundings
from entering the operating room and the protected area. Outside the operating room the ventilation using
high air flow rates and extensive filter technology for suspended matter can be omitted.
In the context of planning, the surgeon should specify in writing the intended utilization of the operating unit
with detailed information regarding the types of operations (e.g. implantation of alloplastic materials), duration
of the operations to be performed, dimensions and number of the operating field(s) as well as numbers and
positioning of operating tables or columns, and dimensions and positioning of the instrument tables. Based on
these data the hygienist then specifies the room classes and the air duct systems to be used.
Sterile instruments should be prepared under hygienic conditions equal to those prevailing in the course of the
subsequent operation.
Version A: It is permitted to reduce the air flow rate during periods when the operating room is not used
although flow reversal should then be excluded.
Version B: When not in use (no person present in the room), the ventilation systems as well as the
associated adjoining rooms supplied with over-flow air may be shut down. However, it is to be ensured that
the ventilation and air-conditioning systems are allowed sufficient lead time to be reactivated before being
used again (at least 30 min).
6.2.2.1.2 Concepts H1a
Operating rooms supplied by systems with low-turbulence flow (LTF) in order to obtain a protected area that
includes operating field(s), instrument tables with sterile goods lying open as well as the operating room
surgical team wearing sterile clothing.
LTF systems entire protected areas are characterized by the following:
 a minimum level air velocity for an stabilized LTF;
 a (defined) supply air temperature that is lower than the resulting indoor air temperature;
 a vertical inflow into the protected area via filters;
 taking into account the effects of potential disturbing factors (e.g. operating lamps and satellites, ceiling
mounted units (support arms and equipment racks), monitors, (floor-) heating systems, etc.).
In operational practice protected areas of approximately 9 m (e.g. 3 m × 3 m), usually achieved by LTF
plenum of 3,2 m × 3,2 m have proven themselves to be sufficiently dimensioned standard areas.
Additional it may be necessary to stabilize the LTF by solid flow-barrier (e.g. glas).
However, already at the planning stage the dimensioning requires a differentiated analysis of the space
required for the protected area (positioning analysis).
On account of the great number of possible factors influencing and / or affecting the effectiveness of LTF
systems a system test in accordance with C.2 is recommended. By this test the performance of the air duct
system within the context of the operating room is made transparent for users, VAC-consultant, hygienists,
and the relevant authorities, thus enabling a basis for further planning to be obtained in addition to the
manufacturer's information.
The aforementioned potential disturbing factors should be considered very carefully in cooperation with the
hygienist and the VAC-consultant taking into account that fulfilment of the respective requirements is to be
ensured. In any case the protection effect shall be demonstrated (C.3 or C.4 or C.5).
Operating rooms of class H1a are recommended, e.g. for the following operations and special requirements:
 orthopaedic and trauma surgery (e.g. on bones and large joints with implantation of foreign material,
polytrauma);
 neurosurgery (e.g. at the spinal column);
 thoracic surgery (e.g. opening the sternum);
 transplantations (e.g. of whole organs);
 interdisciplinary use of the operating room;
 cardiac and/or vascular surgery (e.g. vascular prostheses);
 gynaecology (e.g. breast prostheses);
 general surgery (e.g. hernia net implants);
 operations with a duration of several hours (e.g. tumour operations with large operation field);
 operations with time sums (of approximate duration, storage time of openly arranged instruments, and
incision-to-suture time), which ensure low levels of germ/particle in the protected area exposure only
under LTF plenums.
6.2.2.1.3 Concepts H1b
By means of a LTF plenum of smaller size a protected area reduced to < 9 m can be marked off within these
operating rooms. Class H1b operating rooms are used for operations that do not require to be carried out in
rooms of class H1a.
This can be the case in special clinics performing operations of a clear-cut catalogue of indications.
6.2.2.1.4 Concepts H1c
For these operating rooms with mixed flow it is not possible to mark off a defined protected area. Operating
rooms of the room class H1c are used for operations such as:
 inserting small implants (e.g. coronar stents);
 invasive angiography;
 heart catheterizing.
Class H1c operating rooms should be operated with overpressure.
In order to prevent germs and particles from being transmitted through the air when opening an OR door and
entering the operating room during an operation, the construction should comprise an air lock. Such air lock-
type rooms can be patient preparation rooms or rest rooms, etc. The locking function can be achieved directly
(by supply air connection) or indirectly (by over-flow from the operating room).
Operating rooms of class H1c should not be connected directly to any corridors by doors.
6.2.2.2 Concepts for patients with a risk of infection, H2
This room class comprises rooms for patients with a risk of infection requiring protective isolation / sterile care.
The main risk as far as airborne germs are concerned is caused by Aspergillus spores.
Room class H2 can be required for patients before and after bone marrow transplantations.
These patient rooms have an anteroom serving as an air lock (of approximately 10 m ) and they show an
overpressure compared with the air lock. Furthermore, the air lock is of high pressure compared to all
adjacent rooms.
The use of LTF plenum outside the operating area has led to a significant reduction of the infection frequency
only for certain purpose (e.g. burning patients).
6.2.2.3 Concepts for infectious patients and source isolation, H3
This room class comprises rooms for infectious patients as well as rooms in which health-threatening substan-
ces can be released. Due to the aerogen transmission path a source isolation is required.
With these rooms, the primary focus is on the protection of staff and third parties. Therefore, contaminated air
from these rooms should not be released into the surroundings.
These patient rooms have an anteroom serving as an air lock (of approximately 10 m ) and they show a low
pressure compared with the air lock. Furthermore, the air lock is of low pressure compared to all adjacent
rooms.
Room class H3 can be required in the case of the following indications:
 H3a: e.g. multi-resistant tuberculosis: H-13 extract air filter;
 H3b: e.g. radio-nuclides (see other bodies of rules and regulations);
 H3c: e.g. Lassa fever: H-13 supply air filter and extract air filter in patient rooms as well as air lock;
 H3d: e.g. special rooms the ventilation system of which can be reversed from overpressure to under-
pressure and vice versa. H-13 supply air filter and extract air filter.
When rooms (and anterooms) of class H3a, H3c or H3d are not in use and the H-13 filters has changed (no
person present in the room) their ventilation systems may be shut down.
Rooms in which strong smells, e.g. toilets, are released, however, exempt from this permission, although the
extract air flow rate of such rooms may only be reduced to 50 % of the nominal flow rate. In addition to that,
for each patient room dampers of tightness class 4 in accordance with EN 1751 should then be provided for
sealing the supply air and extract air ducts.
When any rooms of class H3b are not in use (no person present in the room) their ventilation systems may
only be shut down if no health-threatening radiation or substances are released, e.g. such as cause muta-
genic, cancerogenic or teratogenic effects.
Version: When conducting bronchoscopy large volumes of aerosols are released. The search for tuberculosis
is quite frequently conducted by means of bronchoscopy.
6.2.2.4 Concepts for other medically used rooms, H4
This room class comprises all medically used rooms which cannot be assigned to room classes H1 to H3.
Class H4 rooms can be used for patients before and after transplantations (heart, kidneys, lungs, liver).
When no person is present in the room the ventilation system may be shut down. Rooms in which strong
smells, e.g. coloscopy, are released, however, exempt from this permission. The extract air flow rate of such
rooms may only be reduced to 50 % of the nominal flow rate.
In areas used by varying numbers of people, e.g. waiting areas, increased odour loads can temporarily occur.
The supply air and extract air flow rates should therefore be adjusted to the respective odour loads. In order to
enable an efficient operation of the ventilation system, the installation of a variable air flow rate system is
considered to be practical, e.g. a system using CO sensors as transducers.
6.2.3 Requirements
In accordance with the division of the room classes the technical data regarding dimensioning and operation
of the VAC system are represented in Table 1 form for the individual groups of rooms.

Table 1 — Classification of the room air classes according to hygienic requirements
a
Classification Scope (examples) Protected zone Pressure level
Protected operating zone within the operating room for orthopaedic and trauma
surgery (e.g. on bones and large joints with implantation of foreign material, poly-
trauma), neurosurgery (e.g. at the spinal column), thoracic surgery (e.g. opening the At least 9 m by
H1a sternum), transplantations (e.g. of whole organs), operations with time sums and
means of LTF
low levels of germ exposure, interdisciplinary use of the operating room, cardiac outlet
Slight overpressure
and/or vascular surgery (e.g. vascular prostheses), gynaecology (e.g. breast
H1 in the operating room
prostheses), general surgery (e.g. hernia net implants)
Protected compared to rooms
operating zone adjacent to the
Reduced protected operating zone within the operating room, e.g. for eye surgery,
< 9 m by means
operating room
H1b
urological surgery of LTF outlet
No defined protected operating zone within the operating room for other operative
No defined
H1c
interventions (e.g. insertion of small implants, invasive angiography, heart
protected zone
catheterisation, endoscopic examinations of sterile body cavities)
H2 Clean areas (protected zone) in patients bedrooms for special treatments (e.g. bone
Overpressure ≥ 6 Pa
Protective isolation marrow transplantations)
H3a E.g. multi-resistant tuberculosis
Underpressure
H3b E.g. radio-nuclides
≥ 6 Pa
H3
H3c E.g. Lassa fever
Source isolation
Selectable over- or
H3d E.g. special rooms for which overpressure or underpressure can be selected
underpressure ≥ 6 Pa
All other hygienically relevant rooms not belonging to any of the classes H1, H2 or
H3; this includes, e.g. patients bedrooms, intervention rooms, surgical dressing – –
rooms, intensive care unit, dialysis centre.
H4
Slight underpressure
Other rooms
in the room adjacent
Rooms adjacent to operating rooms – to the operating room
compared to the
operating room
7 Requirements for ventilation and air-conditioning components
7.1 General requirements
7.1.1 Servicing
All air distributing components of the VAC system should be within easy reach and should, for reasons of
hygiene, preferably be arranged so that entering class H1 rooms for cleaning and maintenance can be
avoided.
If the accessibility required for servicing can only be ensured via room class H1, the rooms concerned should
be cleaned and disinfected after every inspection or maintenance, respectively.
7.1.2 Contaminations
Supply air and recirculation air systems in all air distributing areas should be designed, operated and serviced
such that inadmissible contamination of the supply air by inorganic or organic substances, e.g. harmful gases
within the system, are reliably avoided and the air is perceived as odourless. The outdoor air should be taken
as reference if health-related guideline values for the content of germs, biological and chemical components
(e.g. MVOC [microbial volatile organic compounds], endotoxins, allergens) are not yet available. The content
of dusts, bacteria, fungi, and biological components in the supply air should not exceed that of the outdoor air
at the relevant site.
7.1.3 Surfaces and materials within the air flow
Supply air and recirculation air systems in the air-distributing area should be made of materials that neither
emit harmful substances nor represent a nutrient medium for microorganisms. For this purpose it should be
ensured that only such devices and system components are used which do not release any harmful
substances, fibres, and odours into the air flow or the rooms, respectively, and do not stimulate the growth of
microorganisms. Any porous linings within the air flow should be covered with suitable abrasion-proof material
(e.g. glass silk cover). Glass and mineral fibre mats used for insulation should not be in direct contact with the
transported air.
Air distributing surfaces should be designed and manufactured such that a deposit of dirt is not promoted.
7.1.4 Cleaning management planning
All components should be delivered in a cleaned condition and be protected against contamination and
damage during the course of construction. For this purpose a cleaning management plan should be
established for all crafts involved in the construction. The VAC systems should be installed such that all the air
distributing components are in a hygienically impeccable condition at the time of commissioning.
For the subsequent operation it should be ensured that the entire system can be inspected without
considerable technical effort and can be cleaned and disinfected, if required, with justifiable technical effort.
Appropriate openings sufficient in number and size should be provided in order to facilitate access to the
areas to be cleaned.
7.1.5 Labelling
All system components should be visibly and permanently labelled or marked, respectively, so that their
function and coverage area can be recognized clearly and at all times.
7.2 Outdoor air suction, exhaust air plenums, and surroundings
When planning VAC systems it should be ensured that by the type and position of the outdoor air suction the
least polluted outdoor air is taken in. The lower edge of the suction opening for outdoor air should be at least
3 m above the ground; a sufficient distance should also be provided with regard to other reference levels
relevant for air hygiene (horizontal surfaces, buildings, etc.).
Typically, the following influences should be taken into account:
 meteorological conditions (e.g. frequently occurring strong winds);
 flue gas issuers, cooling towers/re-cooling plants (see NOTE);
 odour sources or other sources of disturbance (e.g. sanitary ventilations);
 existing or possibly planned neighbourhood buildings (e.g. tall buildings; see municipal development
plan);
 traffic or proximity of (underground) car parks, parking lots, delivery areas, helicopter landing site;
 high external thermal loads.
In cases of doubt expert opinion can be required.
NOTE Due to the special danger potentials of re-cooling plants, it should be duly considered during the erection of
the cooling towers that the escaping aerosols do neither enter suction openings of ventilation installations nor occupied
rooms through opened windows. Solid deposits or bio-films (bio-fouling, scaling) inside the cooling tower should be
restricted by feed-water treatment appropriate to the given water quality.
Short circuits between exhaust air and outdoor suction air should be avoided by a sufficient distance or by
appropriate technical or structural measures, respectively. As minimum distances the requirements of
EN 13779 should be complied with.
The suction opening should not be freely accessible for unauthorized persons.
The suction of larger air contaminants should be avoided by using a corrosion-resistant wire mesh grating
(maximum mesh size of 20 mm × 20 mm), which should be accessible for mechanical cleaning on the dirt
side.
In the case of danger of icing, suitable measures should be provided for.
Moreover, the floor area behind the suction opening should have the form of a basin (minimum length of
0,5 m) for cleaning and precipitation water, snow, etc., which might enter through the opening.
Exhaust air by which high dust loads, humidity, odours or other polluting emissions are released, in particular
from departments for the treatment of infectious diseases, animal housings, pathology departments, labora-
tories, laundries, and rooms in which radioactive or carcinogenic substances can be released, should be
directed into the open through a separate air duct the end of which is installed on the roof.
7.3 Air ducts
7.3.1 General requirements
In order to facilitate cleaning and maintenance of air ducts, components such as sound attenuators, dampers,
and heat exchangers should preferably be installed inside the VAC-central-plant.
All ductwork should be made from mechanically durable, non-biodegradable materials.
On the inside they should be abrasion-proof, corrosion-resistant, and smooth (e.g. galvanized sheet steel).
Fittings and connectors, bracings, and other built-in parts should be designed so as to avoid local deposits of
particles and enable both manual and mechanical cleaning. Bracings should preferably be installed on the
outside. If an inside installation is required, e.g. due to increased pressure loads, the bracings should have
round profiles.
There should be no sharp edges in order to avoid injuries.
According to EN 12097, connecting and fastening elements, such as threads, shanks of screws, etc., should
not protrude into the air distributing area by more than 13 mm. Internal flanges are to be avoided.
Structural cavities (e.g. installation shafts, areas between double walls or suspended ceilings, respectively,
false floors) should not be used for an unducted air distribution unless they are intended to ensure the
underpressure, if any. This does not apply to coated channels specifically designed and constructed for air
distribution, such as channels made of concrete or brickwork.
Flexible air ducts are permitted only for the connection of air terminal devices and equipment and with them
only up to a length of ≤ 1 m. They should be easily accessible when located in areas of room class H1.
Seals and sealing means should be smooth, abrasion-proof, have closed pores, and be resistant to
disinfectants and ageing. The materials used should pose no health risk. If only certain disinfectants, e.g.
alcohol-based disinfectants, are intended to be suitable, this should be pointed out explicitly in the
manufacturer’s maintenance instructions.
The use of injectable joint sealants should be avoided; it is allowed only in joint areas and only to a small
extent.
Any installations leading through the air duct walls should be constructed such that the tightness requirements
are met. There should be no installations inside the air ducts which do not belong directly to the VAC system.
The maximum specific leakage, q in l/(s ⋅ m ), of operable air duct networks should be in accordance with
L
class C / B (see the following versions A / B) of EN 13779.
The test pressure p should be
Version A: 1 000 Pa
Version B: 400 Pa
and may deviate in exceptional cases if so agreed by the parties concerned.
For ducts in cavities of room class H1 metrological examinations of the specific leakage of the duct network
should be carried out in accordance with EN 12237 and EN 1507.
As a matter of principle, insulating material should be placed on the outside of the air ducts. If condensation
cannot be ruled out the insulating measures should be vapour diffusion tight.
If ductwork is to be removed completely or in parts for cleaning purposes, the required structural provisions
should be planned and described.
Air duct sections which have to be cleaned using vapour or liquids should be designed and constructed such
that they are waterproof and have a slope leading towards a closable water discharge opening.
If the system concept provides for the ventilation channels to be cleaned mechanically, appropriately sized
inspection openings or easily removable duct parts or fittings should be installed for inspection and/or cleaning
purposes. Furthermore, access to the relevant duct parts or fittings should be ensured.
7.3.2 Outdoor air duct
The following additional requirements apply to outdoor air ducts:
 the air duct between outdoor air suction and VAC-central-plant should be designed as short as possible;
 the duct section between outdoor air suction and VAC-central-plant should be provided with cleaning
openings sufficient in number and size enabling a comprehensive inspection and mechanical cleaning of
the inner walls to be carried out;
 basins and discharge openings for cleaning and precip
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