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Chapter 4

بسم الله الرحمن الرحيم

In The Name Of God The Most Merciful The Most Compassionate

 

Thesis البحث

 

 

Ch4: Natural Ventilation

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Bibliography		 Natural Ventilation is the process by which spaces exchange indoor air with outdoor air without the use of any mechanical system. This can be induced by wind effects, by which  air is driven though or out of the space via windows or other openings. Air movement can also be induced by buoyancy, due to the difference in density (due to temperature differences) between the air outside the space and the air inside. The less the density of the air, the higher it will rise. This will create a low pressure region in the lower areas of the space for the denser air from outside to replace and fill (2). These two factors for natural ventilation to occur are discussed in more detail in the following sections;

Natural ventilation must fulfill the following  criteria:

1. Provide  Oxygen and remove Carbon dioxide:

2. Remove Odour

Air Space per person (m )

Min Ven. Requ. Adults l/s

Min Ven, Requ. Child l/s

13.4

3.3

5.7

5.7

7.5

9.9

2.8

11.8

13.7

Table 4.2: Minimum required ventilation to dilute odour per person per m of the space (10)

3. Remove Bacteria

4. Remove  Hazardous Gases

Pollutant

Ambient air

Long term

Level (mg/m )

  Avg. Time (years)

 

Short term

Level (mg/m )

Avg. Time (h)

  Occupational

Level (mg/m )

  Avg. Time (h)

SP

75

1

260

24

5

8

CO

-

-

10

8

55

8

HCHO

-

-

-

-

0.12

continuous

NO2

100

1

-

-

9

instantaneous

NO

-

-

-

-

30

8

Rn

0.015WL

1

-

-

1WL

instantaneous

O3

-

-

235

1

0.2

8

1 WL = 1.3 X 10 Me V/l of air.

Table 4.3 Maximum Recommended indoor air pollutants (1)