Pressure Differential Systems differential systems... · Consideration in EN 12101-2:2003 •...

I.F.I. Institut für Industrieaerodynamik GmbH

III. International FDBES CAD ForumOctober 19.-21. 2007 Miedrzyzdroje 1/22

Pressure Differential Systems

German point of view to EN 12101-6Considaration of the influence of aerostatic pressure differential

in high rise buildings

I.F.I. Institut for Industriel Aerodynamics GmbHInstitut at the University of Applied Sciences

Welkenrather Straße 120Germany - 52074 Aachen

Dipl.-Ing. B. Konrath

notified Test, Inspection and Certification Body no. 1368in accordance with Construction Products Directive



∆ptherm = (ρTR - ρ0) · g · hTR

Aerostatic pressure distribution

aerostatic pressure differenceinside/outside

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-150 -100 -50 0 50 100 150

pressure (Pa)

build

ing

heig

ht (m

)

winter 24/-20 °C

summer 24/35 °C

(1)



measured and with equation (1) calculated pressure difference between staircase and ambient in a 38 storey tall building (ti = +20 °C ta = 8 °C)

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-60 -50 -40 -30 -20 -10 0 10

pressure difference (Pa)

flor (

- )

dp in-out eastsidedp in-out westsidedp theoretical




pressure differential between staircases and ambient for a 200 m high rise building (ambient temperature at ground level t = 5 °C, measured and calculated (without wind influence) with equation (2))


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-100 -80 -60 -40 -20 0 20 40 60 80 100 120 140 160 180 200

pressure / Pa

stor

ey

measured pressure differential (staircaise -ambient)pressure difference calculated from measured temperatures

measuring points in staircaseexternal measuring points



high suction on the leeward side due to flow displacement

wake with strong three dimensional flow closing only in a large distance from the building

strongly modelled horse shoe vortex resulting in high over speed at the edge regions at the ground level

stagnation point in 2/3 of the height

local flow separation at façades

Flow field around buildings

Plate shaped high rise building, wind flow perpendicular to the longitudinal axis



Plate shaped high rise building, wind flow parallel to the longitudinal axis

weakly modelled horse shoe vortex, thus a low over speed at the edge regions at ground level

windward side(wind stagnation, i.e. over pressure)

leeward side (suction)

wake closes downstream in only a short distance from the building

separated flow (zones of highest suction)

reattaching flow




Tower high rise building

separating flow, due to short length no reattachment at the building sides

suction at leeward side is lower than at the plate shaped high rise with wind flow perpendicular to the longitudinally axis because the wake is less pronounced

widely two-dimensional flow pattern with quick closing wake

weakly modelled horse shoe vortex, thus small over speed at the edge regions at ground level due to displacement




(2)smpMM /3,7)10/100(10,u100,u =⋅= α

windprofile

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0 2 4 6 8 10speed (m/s)

heig

ht (m

)







typical wind induced pressure differential for a high rise building with square cross section and windows opened at the windward and leeward side


wind wind



Pressure distribution in staircases

22

22TR

vv

AV

p

v

p&

⋅

∆=

∆=

ρρζ

staircase type 1: ζ = 25 staircase type 2: ζ = 56

(3)



building height 160 m, ambient temperature +30°C, inside temperature +22°C

pressure difference staircase - ambient

Zeta = 25

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0 50 100 150pressure difference / Pa

stor

eypressure difference staircase - ambient

Zeta = 50

0

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0 50 100 150pressure difference / Pa

stor

ey

Pressure distribution in staircases



static pressure in safety lobbies and fire fighting lobbies influenced by other vertical shafts

Pressure in lobby



Pressure difference in smoke layer

ρα

Tr

pAV ∆⋅⋅⋅=

2.

hgRG

TrTrtherm ⋅⎟⎟

⎠

⎞⎜⎜⎝

⎛−⋅⋅=

TT1p∆ ρ

fire storey

over-pressure relief

staircase

lobby

(4)

(5)



hgRG

TrTrtherm ⋅⎟⎟

⎠

⎞⎜⎜⎝

⎛−⋅⋅=

TT1p∆ ρ ⎟⎟

⎠

⎞⎜⎜⎝

⎛−⋅⋅⋅=

TT12

32 h

. 2/3

RG

TrgbV α

in flow vs door height fire room temerature 100°C

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0,5

1

1,5

2

-3,0 -1,0 1,0 3,0air speed / m/s

heig

ht /

m

neutral level in half height

neutral level at the top

pressure distribution vs door height fire room temerature 100°C

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1,5

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-4,0 -2,0 0,0 2,0 4,0 6,0pressure difference / Pa

heig

ht /

m

neutral level in half height

neutral level at the top

Pressure difference in smoke layer

(5)(6)



Consideration in EN 12101-2:2003

• buoyancy experienced by hot gases on the fire storey,

• thermal expansion of hot gases in the fire zone,

• stack effect throughout the building

• wind pressure forces and

• HVAC systems.

Main driving forces on „pattern of movement“



Demand: door pressure difference min. ∆p = 50 Pa

reasonable pressurizationdemand (subordinated to the opening force): 15 Pa ≤ ∆p ≤ 65 Pa

reasonable general demand:

F ≤ 100 N

Caution if wide and/or tall doors on escape ways are used!!!!

Consideration in EN 12101-2:2003



Demands of the German building regulations und high rise guidelines:

• over-pressure in staircase min. ∆p = 15 Pamax. ∆p = 100 N / 2m²

• necessary staircase volume flow rate = 20.000 m³/h• safety staircase volume flow rate m³/h

V&5,1hbkV ⋅⋅=&

• airflow from lobby to the fire storey under consideration of out flow of fire gases

Consideration in German high rise guidelines



Possibilities for calculation

Computer software for multizone buildings (zone-link-models)

Consideration of 3D-modeling based on the fundamental equations

• different leakages,• fan characteristic curve,• flow components characteristic curve, etc.

Druckdifferenzen

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0 50 100 150 200 250 300Druck (Pa)

Höh

e (m

)

TR-außenTR-außen (RS)TR->SCHTR->SCH (RS)Lobby->FlurLobby->Flur (RS)

Pressure difference in a 150 m high building



Technical notes

• At buildings with small height a pressurization with simple systems is possible. An active pressure control system is normally not necessary.

• Medium-rise buildings need active controlled pressurization systems.

• Buildings with heights of 100 m and more must have a pressurization concept which considers the influences of other vertical shafts to the horizontal pressure distribution. Normally the pressure control of the other shafts has to be considered.

• Active control systems, possibly large out flowing areas will become necessary, must work quickly so that the door opening forces after closing are small.

• Facades must close automatically in case of fire to control the pressure situation inside the building.



Conclusions

• Aerostatic and aerodynamic effects play a big part on the pressurization of staircases.

• For buildings with small height the stack effect has not to be taken into account.

• Pressure differences depending on natural wind have to be considered. The effect on low rise buildings however is less strong.

• At buildings with a height above 60 m the building concept must consider the physical effects. Pressurization control is usually necessary.

• At buildings with an height of 100 m and more a general view to the whole building with quick working active pressure control systems is unavoidable.

• The EN 12101-6:2003-09 does not take into account the fundamentals of physics.

• The EN 12101-6:2003-09 does not include a test regulation as a requirement for CE marking.



Thank You very much for Your Attention.

Dziękuję bardzo za uwaga.

If you have any questions I will do my best to answer them.



notified Test, Inspection and Certification Body no. 1368in accordance with the Construction Products Directive

I.F.I. Institut for Industriel Aerodynamics GmbHInstitut at the University of Applied Sciences

Welkenrather Straße 120Germany - 52074 Aachen

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Pressure Differential Systems differential systems... · Consideration in EN 12101-2:2003 •...

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