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FUNCTIONS OF VENTILATION:-

•  Natural ventilation & air movement could be conideredunder t!e !eadin" o# $tructural control%

• 'ue to !uman com#ort( it deerve a e)arate ection

• It !a t!ree di##erent #unction:-* Su))l+ o# #re! air

, Convective coolin"

.!+iolo"ical coolin"

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SU..L/ OF F0ES1 AI0

•T!e re2uirement o# #re! air u))l+ are "overned b+ t!e t+)e o#

occu)ation( number & activit+ o# t!e occu)ant b+ t!e nature o#

an+ )roce carried out in t!e )ace

•In number o# air c!an"e )er !our

•T!e )roviion o# )ermanent ventilation i o)enin" 3!ic!

cannot be cloed4ma+ be com)ular+

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CONVECTION COOLIN5

•T!e e6c!an"e o# indoor air 3it! #re! out-door air can )rovide coolin"

•T!e movin" air act a a !eat carr+in" medium

•A ituation 3!ere t!i convective coolin" i a )ractical

 )ro)oition( arie in moderate or cold climate7 8!en t!e

internal !eat "ain i carr+in" a tem)erature increae( but alo

in 3arm climate( 3!en t!e internal !eat "ain or olar !eat

"ain t!rou"! 3indo3 3ould arie t!e indoor tem)erature even

!i"!er t!an t!e out-door air tem)arature

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.0OVISION FO0 VENTILATION:

STAC9 EFFECT:

 

VENTILATION 'UCT A00AN5EENT

  Internal bat!room on t+)ical intermediate

#loor

  *vertical

  ,!ori;ontal

Fi"ure !o3 ome duct arran"ement #or

multitor+ buildin"

T!e tac< e##ect relie on

t!ermal #orce et u) b+

denit+ di##erence bet3een t!e

outdoor & indoor air 

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'UCT 'ESI5N 50A.1:

'ELIVE0/ 0ATE FO0 'UCT LEN5T1S IN'ICATE'

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T!e motive #orce i t!e tac< )reure multi)lied b+ t!e cro

ectional area 7#orce in N ( area in m,=t!e tac< )reure can be

calculated #rom t!e e2uation-

  >>?, 6 ! 6 @t

  !!ei"!t o# tac< in m

  @ttem)erature di##erence in de"ree c

Suc! !a#t ue #or t!e ventilation o# internal ( 3indo3le room 7bat!room & toilet=

in Euro)e

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.1/SICAL COOLIN5:

T!e movement o# air )a t!e

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1ere 3e mut e6tend t!i anal+i &e6amined !o3 t!e #lo3

o# air t!rou"! a buildin" 3ill be in#luence b+ 3!at #actor

8!en movin" air tri

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T!e )reure i )ro)ortionate to t!e air velocit+( a

e6)reed b+ t!e e2uation:

  . 3 >B*, 6 v,

8!ere .33ind )reure Nm,

  v3ind velocit+ mec

A e)aration la+er i #ormed bet3een t!e ta"ment air & t!e

 buildin" on t!e !and t!e laminar air #lo3 on t!e ot!er !and