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Smoke ventilationthrough façades
4RWASmoke and Heat Ventilation Systems
update
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Contents
Preface
Research results confirm custom and practice
Design basis for smoke ventilation through façades
Applications
The right solution for every building
Planning and design
DIN 18232 Part 2
Window design types
Systems
Fulfilling design and regulatory requirements of buildings
Conclusion
Publication notes
Smoke ventilationthrough façades
Smoke ventilationthrough façadesPage 2
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Preface
Smoke ventilationthrough façadesPage 3
In addition to building regulations, the relevant standard in Germany for the calculation and planning
of smoke and heat ventilation systems is DIN 18232.
The absence and lack of activity at European level has enabled work to continue very successfully on
DIN 18232 Part 2, which deals with the design of natural smoke and heat ventilation systems. Since
the beginning of 2003 the draft has been available as a White Paper for publication. The results are
of considerable importance for architects, planners and façade fabricators in Germany, Europe and
throughout the world.
This revision was not only urgently required for scientific reasons but also for a long-needed regulation
relating to smoke ventilation through the walls of buildings. The previous standard only covered the
ventilation of smoke from buildings through roofs. The revised addition now contains wide-ranging
standard and specification details of how effective smoke ventilation can be achieved through openings
in a building’s vertical exterior skin.
Excellent examples for well-designed smoke and heat ventilation concepts in major buildings of the
last few decades include the Commerz Bank high-rise building in Frankfurt and the Alexander plaza
radio tower in Berlin.
A vast number of buildings are and have been constructed featuring smoke ventilation through windows
in the vertical façades. Nevertheless many questions concerning this type of application remained
unanswered, and now these have been dealt with in great detail in the revised standard. In addition
to the normal references relating to the components used, Appendix C of the standard particularly
deals with the aerodynamic assessment of the building window openings, providing valuable assistance
to consultants and architects in the planning and design of buildings. It has been unclear in the past
how to design smoke ventilation through the walls of buildings, particularly where wind plays a role,
in order to ensure that escape and rescue routes or relevant parts of the building can be kept reliably
free of smoke in the event of an emergency. All too often the discussion has centered on how wide a
window leaf must be opened to achieve an aerodynamically efficient cross-section and, above all,
which type of opening is best. The standard provides answers to these questions, which are also
illustrated in this publication.
Research results confirmcustom and practice
Design basis for smoke ventilationthrough façades
Applications
Smoke ventilationthrough façadesPage 4
Applications
Smoke ventilationthrough façadesPage 5
The natural smoke ventilation of buildings through façades has been a custom and common practice
for many years and is a method used in the most diverse type of buildings. Examples of this include
residential buildings with staircase and lobbies that act as escape and or rescue routes, office and
administration buildings, sports centers, atriums, shopping centers, public buildings such as airports,
railway stations and exhibition centers, as well as commercial halls. Natural smoke ventilation through
the roof is not always possible due to the construction and design of the building.
The revision of DIN 18232 Part 2 has given full consideration to this common practice of natural
smoke ventilation through vertical building openings and thus formed the basis for planning and
designing smoke ventilation systems in exterior walls.
The great benefit of smoke ventilation through the façade is the possibility of being able to use a whole
range of different window designs. This gives the designer an extraordinary amount of scope to design
smoke ventilation systems with freedom and imagination backed by the assurance of proven reliability
of electrically driven smoke and heat ventilation systems.
The right solution for every building
“This standard applies to the design and installation of natural smoke ventilation systems for buildings
requiring smoke ventilation describing the requirements for roof mounted ventilation in DIN 18232-
1 for single-storey buildings and top storey sections of multi-storey buildings, as outlined in Part 1.
In addition Part 2 of this standard also provides informative notes for the design and installation of
natural smoke ventilation systems for buildings with smoke ventilation through the exterior walls.
This standard contains tables and calculation methods for designing low-smoke layers to comply with
the requirements for various safety limits. This standard contains notes and definitions that must be
complied with when using these design rules and for the installation of natural smoke ventilation
systems.”
Note:
The regulations in building regulations relating to smoke ventilation systems, for example in the form
of smoke ventilation openings of a specific size in staircases or at a specific distance from fire walls,
are not affected by this. Special verifications are required for deviations from this standard.
(Original text of DIN 18232 Part 2)
As a result of the rewording of the applications for DIN 18232 Part 2, it is now possible for the first
time to plan and design smoke ventilation systems through the vertical surfaces of buildings to a
standard. This method, which has been acknowledged and used successfully for decades in many
thousands of projects, is now reflected in the standard.
Terminology definitions:
● Smoke section area AR
● Low-smoke layer d
● Fire development time "t = t1 + t2"
● Rate of fire spread
● Design group
● Smoke ventilation area Aw
● Air supply area Azu
To produce a design that complies with DIN 18232 the designer must start by finding all the parameters.
Smoke section area AR
The building is split into sections. These are split into smoke section areas AR where possible and
necessary. The maximum AR is 1600 m². Larger smoke section areas are possible but in this case the
aerodynamic smoke ventilation area AW
must be increased in size by 10% of the 1600 m² of the AW
area for every additional 100 m² of area.
The resulting smoke section areas are separated from each other by smoke aprons. The appropriate
rules governing the use of smoke aprons are also set out in DIN 18232 Part 2.
DIN 18232 Part 2
AR <= 1600 m2
AR > 1600 m2 => Division with smoke aprons
1600 m2 < AR < 2500 m2 is possible if, for every additional 100 m2 of AR , Aw is increased by 10% of Aw1600
Planning anddesign
Smoke ventilationthrough façadesPage 6
Smoke-layer d
Low-smoke layer is at least d = 2.5m
Fire development time
To define the required smoke ventilation area AW in DIN 18232 Part 2, a fire development time is
defined, which applies exclusively for the needs of this standard. This is made up of two times – first
of all the time from the fire creation to the fire alarm and then the time from the fire alarm to the actual
fire fighting. The appropriate details are provided in section 5.6 of the standard, and on the basis of
these details it is possible to calculate the fire development time required for a specific project.
Rate of fire spreadIn addition to the fire development time a fire spreading rate is also defined. This contains an assessment
of the expected fire on the basis of the substances stored in the area, the presence of a sprinkler system
and the possibility of a fire alarm system.
Now the design group required for calculating the AW
value can be taken from Table 2 "Design groups".
Planning anddesign
Expected firedevelopment time (see 5.6)
≤ 5
≤ 10
≤ 15
≤ 20a
> 20
particularly low
Design group for afire spreading rate
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3
4
5
mediuma particularly high
Table 2: Design groups
3
4
5
5b
5b
min
a Average values without special verification; if these average values are used they require design group 5.
b In these cases the safety aims of this standard cannot be achieved solely by the natural smoke ventilation system. Othermeasures are required to achieve the safety aims.
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5b
Smoke ventilationthrough façadesPage 7
Smoke ventilation area Aw
The smoke ventilation area is found using the
design group, room height and the height of the
low-smoke layer from the corresponding Table
3 (from DIN 18232 Part 2): Required smoke
ventilation area AW [m²] per smoke section.
This full smoke ventilation area is then split into
an appropriate number of façade openings (na-
tural smoke ventilation) using the corresponding
regulations provided by the standard. The façade
openings found in this way should be installed with a maximum distance from the top of the façade
opening to the ceiling of 0.50 m in at least two facing exterior walls in a smoke section. The façade
openings should be completely inside the smoke layer; the bottom of the discharge opening should
be at least 0.5 m above the limit of the calculated low-smoke layer (as shown in Table 3, DIN 18232
Part 2).
Calculation of the AW value for normal wall openings using the flow rate coefficient and the clear
window opening b · a.
Aw = b · a · cv
The opening angles specified in Table C.1 are subject to a maximum tolerance of ± 5°. The standard
regards a turning leaf as identical to a tilting leaf.
This means that the following conditions apply: To find an AW value, a smoke and heat ventilation
system opening must always open at least 25°. Opening angles of over 60° improve the AW
value only
slightly.
Air supply area Azu
The air supply areas must be fully contained in the low-smoke layer. The top of the air supply opening
must be at least 1.0 m away from the smoke layer limit. This distance may be reduced to 0.5 m around
doors or windows with a maximum width of 1.25 m. If windows are used as air supply openings, turning
leafs that open inwards represent the best solution. In any event it must be ensured that the incoming
air does not stream straight into the layer of smoke gas and that this impulse does not cause any eddying
of the smoke gas. The air supply must be fed into the building close to the floor and as far away as
possible from the smoke gas layer.
Table C.1:
Flow rate coefficients for different opening types
Opening type
Completely open area
Louvers
Tilt or turn leaf
Tilt or turn leaf
Tilt or turn leaf
Flow rate coefficient cv
0.65
0.65
0.5
0.4
0.3
Opening angle
90°
≥ 60°
≥ 45°
≥ 30°
Planning anddesign
Smoke ventilationthrough façadesPage 8
The following are regarded as air supply openings:
Independent air supply devices, gates, doors or windows if they are labeled on the inside and outside
as air supply openings for natural smoke ventilation systems using signs that comply with DIN 4066
and can be opened from the outside without being destroyed (for example no breaking of window panes
or demolishing of wall or gate areas). This does not apply if the plant fire service can create the
appropriate air supply openings. It must be possible for the air supply areas to be opened immediately
(for example automatically, by the plant fire service, by operational or organizational precautions) after
the natural smoke ventilation system has tripped.
Actuation in windy conditions
The spread and ventilation of smoke gases depends to a large extent on the air flow in the room. The
room air flow, in turn, is influenced by the exterior wind pressure exerted on the natural smoke
ventilation and air supply areas. This means that the influence of the wind must be taken into
consideration for smoke ventilation through façades. In the studies and calculations, a reference speed
of smooth air flow of 3.7 m/s was used. This value corresponds to the annual mean value of the wind
speed in many parts of Germany measured at a height of 10 m. The studies show that the opening of
the natural smoke ventilation and air supply areas in the side walls, which is dependent on the wind
direction, is unavoidable. Since these areas must also always be in the side sheltered from the wind,
both the natural smoke ventilation and air supply areas must be installed on at least two opposite
sides of buildings. Smoke and heat ventilation openings and air supply openings must always be located
in the same building wall.
This means that we are now faced with the following two tripping scenarios:
● Wind speed < 1 m/s – open all natural smoke ventilation devices
● Wind speed > 1 m/s – open only the natural smoke ventilation devices and air supply openings on
the side sheltered from the wind
Summary:
Any type of window used in a façade can be used as a natural smoke ventilation device. If it opens upwards
and outwards it offers benefits from an air flow point of view. Top hung window leafs that open at the bottom
and inwards are suitable for use as air supply openings. These offer the best air supply properties.
Table 1:
Correction factors cz for various types of air supply openings
Opening type
Door or gate openings, machine grills
Opening louvers
Tilt or turn leaf
Tilt or turn leaf
Tilt or turn leaf
Tilt or turn leaf
90°
90°
≥ 60°
≥ 45°
≥ 30°
0.7
0.65
0.65
0.5
0.4
0.3
Correction factor czOpening angle
Air supply areas are calculated as follows: Air supply area Azu
= 1.5 · Aw of the largest A
R
The opening angles set out in Table 1 are subject to a maximum tolerance of ± 5°. This means that the
air supply area for each air inlet is calculated as follows: Azu = a · b · cz
Planning anddesign
Smoke ventilationthrough façadesPage 9
Bottom hung outward openingOptimal efficiency when used as a natural smoke
ventilation device.
Bottom hung inward openingMost commonly used window design in Europe.
Ideal for day to day ventilation.
Top hung outward openingHighly suitable for natural ventilation purposes
and replacement inlet air.
Top hung inward openingIdeal for use as a natural smoke ventilation
device since the air supply is guided towards the
floor and thus produces little smoke eddying.
Horizontal centre pivotThis leaf type offers good flow properties for
ventilation purposes. Its design ensures large free
opening areas.
Multi bladed louvresIdeal for use in natural smoke ventilation canbe used for exhaust or replacement inlet air.good flow properties with a high efficiencylevel. Short operating times and large freeopening areas. Also suitable for day to dayventilation.
The most various types of window forms and hanging styles used in exterior walls.
Window design typesPlanning anddesign
Smoke ventilationthrough façadesPage 10
Natural smoke ventilation operating mechanisms
All conventional window design types can be controlled using operating mechanisms that have been
time-tested and in use for many years. The following electric motor systems dominate this field:
● Direct openers with rack, spindle or chain drive units
● Scissor drive systems
Depending on the size and weight of the window and its installation position, additional mechanical
interlocks are used in combination with these mechanisms in order to maintain the security and weather
ability of the window system.
Supporting regulations
● Powered windows, see ZH 1/94 and ZVEI publication "RWA aktuell No. 3"
● Maintenance of electric cable function, see specimen cable system directive (MLAR), which has
now come into force in all states in Germany.
Vertical centre pivotVery suitable for use as discharge leafs for natural
smoke ventilation and ventilation purposes.
Side hung inward or outward openingThis type of leaf can be used as a natural smoke
ventilation discharge device and for air supply
purposes.
Planning anddesign
Smoke ventilationthrough façadesPage 11
Systems Fulfilling design and regulatoryrequirements of buildings
Smoke ventilationthrough façadesPage 12
Systems
Wind direction
Replacement inlet
air openings for
Make up air
Natural smoke ventopenings
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Smoke ventilationthrough façadesPage 13
The technical specification for the control system,
its power supply device and selected actuator drive
units for the buildings smoke and heat ventilation
scheme must fulfill at least the minimum regulatory
requirements and appropriate standards of the
country of installation.
The control system and actuator drive units of
electrically driven smoke and heat vent systems
provide the perfect blend of assured performance
and aesthetically pleasing designs fulfilling all the
requirements of large building complexes to provide
reliable natural smoke ventilation.
Innovative technology
Electric motor driven systems for smoke and heat ventilation systems offer the perfect solution,
particularly for smoke ventilation through building façades operating windows vents and louvres in
the exterior walls. The following contains a description of the system components and the technical
benefits of the system as a whole.
Systems
Smoke ventilationthrough façadesPage 14
Automatic alarmsSmoke sensors, temperature sensors or differential thermal sensors aredesigned to detect a fire as quickly as possible and to activate the smoke
ventilation system automatically.
Natural ventilation, manual and automaticModern smoke and heat ventilation systems can be connected andoperated for natural ventilation by a range of control options, includingmanual push button or key operated switches with automatic functionsincluding wind, rain and temperature sensing. Integration with BMS
systems for modulating control via bus system signaling is also an option.
Actuator drive unitsThe most important component of the system is the electromechanicaldrive unit; (actuator) used to drive open and close windows, vents andlouvres.
Smoke and heat vent control systemControl systems and power supply devices are normally based on amodular expandable system having the flexibility to offer multi smokegroup zoning. Important essential features of any control system shouldinclude primary and secondary power supplies, overriding emergencycontrol, continuous monitoring of systems for fault or malfunction andremote indicating facilities.
Automatic control and sensorsThe actuation of smoke and heat ventilation openings may be dependenton the wind direction and speed so that in the event of a fire, the side ofthe building that is sheltered from the wind is used to ventilate the smoke.
Manual control deviceThe electrical manual control device provides for manual operation ofthe smoke and heat vent system (usually for fireman use) it also indicatesthe operating condition of the system.
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Publication notes
System benefits
The main benefit is the combination of the smoke and heat ventilation functions in the event of a fire
as well as every day natural ventilation.
The smoke and heat ventilation system manufacturer or installer acts as an integrator for both functions
and offers a low cost complete solution.
The exchange of data with other systems using the building control system and bus systems allows
the full use of data and enables complex system solutions to be produced.
The electric smoke and heat ventilation system has a self-monitoring and diagnostic system and reports
on faults or malfunctions automatically.
If the building is extended or undergoes a change of use, the electric smoke and heat ventilation system
can be easily adjusted.
Research into this field is an ongoing process. To date, scientific studies have shown that effective
smoke ventilation through façades is extremely efficient and the design of such systems can be set in
a standard. The publication of DIN 18232/2 represents the first step in this objective and has been
drawn up using the results of investigations carried out by the smoke and heat ventilation specialist
group within the ZVEI at the Institute of Industrial Aerodynamics in Aachen. Further research projects
have also been commenced so that the findings of the investigations are not only sound enough to
provide the necessary design calculation basis for the German DIN 18232 but can also be used as a
major contribution to the finalization of the European standard.
The research continuesConclusion
Publication notes
Publisher: ZVEI specialist group for electrically driven smoke and heat ventilation systemsEditor: Working group for public relationsPhotos: Copyright by: Getty-Images, Creatas, R. Sprang, J. Hempel, GEZEIllustrations: Copyright by: Werbung & Design Armin MeierEdition: First edition, issue date 11/2004Reprinting: Even in extract form and use in digital media only with the written consent of the publisher.
ZVEI have taken every care to ensure that the information contained in this publication is accurate,but regret that they cannot accept liability in respect thereof.
Systems
Smoke ventilationthrough façadesPage 15
Presented by ZVEI member:m
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ZVEIFachverband SicherheitssystemeStresemannallee 19D 60596 Frankfurt am MainPhone: +49-69 / 63 02-250Fax: +49-69 / 63 02-288E-mail: [email protected]
More publications and information areavailable from ZVEI member companies ordirect from the ZVEI (see address below).
Brandschutz-Technik und Rauchabzug GmbHLangbehnstrasse 13 · D 22761 HamburgTel: +49-40 / 89 71 200 · Fax: +49-40 / 890 23 73www.BTR-Hamburg.de · [email protected]
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