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Chapter 4

Air Control in ABuilding

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Chapteroutline

To feelcomfort

Fresh air:At the correcttemperature,

Right amount of moisture,Free from odours and

pollutant

Ventilation ;Process changing the air from

outside to the air in theroom/internal space of a

uilding

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Airsupplies

VENTILATION

!uppl" o#"gen forhuman reath

Control air humidit" and

air $elocit"

Remo$e :

a% caron dio#ide from human reathing

% odours

c% microorganism

d% cessi$e heat energ"

e% 'ater $apor

f% particles such us smo(e and dust

g% $olatile organic compound from sources

such as cleaning

h% comustion products from heating andcoo(ing

i% o)one gas from photocopier and laser

printer

*% methane gas and deca" products from

ground condition

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Ventilationre+uirement

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or(edample4%-

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.umidit"

Rate at'hichuildingmaterial

dr".0121T

3

2urailit"of

uildingmaterials

.eatalance

n

humanod"Comfort

of humanod"

Can causecondensatio

n inuilding

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.umidit"

Saturation

!aturated air is the air that contain the ma#imumamount of 'ater $apour possile at that

temperature%

Saturated Vapour Pressure (SVP)

Vapour pressure increase at the amount of 'ater$apour increase and at the saturation, the $apourpressure reach a stead" $alue called the saturate$apour pressure

!VP is the $apour pressure of 'ater $apour in anair that contain the ma#imum amount of $apourpossile at that temperature

Water vapor- can e de5ned as a sustance in the gases

state 'hich might e li+ue5ed " compression%6 For e#ample, it formed naturall" in the spaceao$e li+uid 'ater 'hich is left open to the air%

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!aturated

air atdi7erenttemperature

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!peci5cation ofhumidit"

!ome of the properties of watervapour:

Moisture content (nit ! "#$%# or dr& air)

Vapour pressure (nit ! Pasca')

Vapour pressure is the partial pressure e#erted "

the molecules of a $apour% The unit is Pascal ew point (nit ! o or "

2e' point is the temperature in 'hich a 5#edsample of air ecomes saturated%

*e'ative +u,idit& (nit !)

The relati$e humidit" of a sample of air comparesthe actual amount the moisture in the air 'ith thema#imum amount of moisture the air can containat that temperature%

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or(edample4%9

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.igrometer

."grometr" or Ps"chometr" is themeasurement of humidit"

.air and paper h"grometer

2e' point h"grometer

et and dr" ul h"grometer

&lectric h"grometer

http://'''%lael%pl/en/re(

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Ps"chometric chart

Ps"chometric chart is a set of graph'hich are comined and sho'ed therelationship et'een the di7erent$ariales used to specif" humidit"

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Ps"chometric chart

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Ps"chometric chart

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or(edample4%

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Condensation in auilding

Condensation in a uilding occurs 'hene$er 'arm

moist air meets surface that are or elo' the de'point of that air

-% !urface condensation

a%occurs on the surface of 'alls, 'indo's, ceilingand =oor%

%1t occurs as a 5lm of moisture or as a eads of'ater

9% 1nterstitial condensationoccurs 'ithin the construction of a uilding as

sho'n in 5g% 4%>

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Causes ofCondensation

ONENSATIO

N

0oisturesources

se of

uilding

Ventilatio

n

Temperature

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Remedies

forCondensation

*EMEIESONENSATIO

N

Ventilation

1nsulation

.eating

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T+an% &ou

for &ourattention

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