The document discusses ventilation systems for buildings. It describes the importance of ventilation for maintaining oxygen levels and removing impurities from indoor air. It provides recommendations for ventilation rates based on space volume and occupancy. Both natural ventilation utilizing wind and stack effects, and mechanical ventilation using fans and ductwork are covered. Key components of mechanical ventilation systems like fans, filters, ducts and diffusers are defined. Design principles for sizing ventilation ducts based on air flow rates are also presented.
3. BUILDING | SERVICES | TWO
(BLD60503)
Ventilation
Requirements
The effect of air on
health and comfort
depends upon:
Movements;
Humidity and
Temperature
6. BUILDING | SERVICES | TWO (BLD60503)
Ventilation system
Ratio Main Elements in Dry atmospheric
Oxygen
21%
Carbon
dioxide
0.03%
Nitrogen
Neon
Helium
Hydrogen
Water
Vapour
79%
7. BUILDING | SERVICES | TWO (BLD60503)
Ventilation
Requirements
Air change important for two reasons:
1.Maintain a satisfactory level of
oxygen content – essential for life
2.To remove impurities
9. BUILDING | SERVICES | TWO (BLD60503)
Ventilation System
Rate of air change = ratio of fresh air
supplied each hour to volume of the
enclosed space
10. BUILDING | SERVICES | TWO (BLD60503)
Ventilation System
Example:
A private office of 30 m3 volume designed for 2
persons:
Recommended m3/hour per person is 43
43/30 x 2 = 2.86 air change per hour
11. BUILDING | SERVICES | TWO (BLD60503)
Ventilation System
Ordinary
conditions
Fresh air supply
of 30 -35m3 per
person per hour
• 1.5 air
changes per
hour for family
of 4
Normal living
room 45 m3:
13. BUILDING | SERVICES | TWO (BLD60503)
Ventilation System
Ventilation rates requirements:
Normally based on recommendations
by authorities or code of practice e.g:
•Department of Occupational Safety & Health
(DOSH)
•Malaysian Standard Code of Practice
14. BUILDING | SERVICES | TWO (BLD60503)
Ventilation System
Apart from fresh air,
movement of air over surface
of body necessary to remove
surplus
•heat,
•water vapour,
•carbon dioxide and
•organic vapours from body
15. BUILDING | SERVICES | TWO (BLD60503)
Ventilation System
Desirable
characteristics of
atmosphere:
•Cool
•Dry
•Diverse in
temperature in
different parts and at
different times
•Moving
Undesirable
characteristics of
atmosphere:
•Hot
•Damp
•Uniform and
Monotonous
•Still
16. BUILDING | SERVICES | TWO (BLD60503)
Ventilation System
Desirable
characteristics of
atmosphere:
•Air change
•Proper means of
ventilation
Undesirable
characteristics of
atmosphere:
•Cubic space
•Excessive cubic
space
17. BUILDING | SERVICES | TWO (BLD60503)
Ventilation System
Ventilation principles:
To prevent undue
concentrations of
odours,
Bacteria carrying particles and
Noxious gases
18. BUILDING | SERVICES | TWO (BLD60503)
Ventilation System
Ventilation principles:
To remove heat from products of
combustion
Body heat and heat from
electrical equipment, motors,
heat from solar radiation etc
19. BUILDING | SERVICES | TWO (BLD60503)
Ventilation System
Ventilation principles:
To remove fumes, dust etc
produced by industrial process
20. BUILDING | SERVICES | TWO (BLD60503)
Ventilation System
Ventilation principles:
To maintain the relative humidity
within reasonable limits
21. BUILDING | SERVICES | TWO (BLD60503)
Ventilation System
Ventilation principles:
Percentage saturation
= Weight of moisture in the air/weight
of moisture if air were saturated at
the same temperature x 100%
Relative humidity (RH)
= Vapour pressure of moisture
present/ Vapour pressure if air were
saturated at the same temperature x
100%
22. BUILDING | SERVICES | TWO (BLD60503)
Ventilation System
Ventilation principles: Relative Humidity
23. BUILDING | SERVICES | TWO (BLD60503)
Ventilation
principles:
To create
air
movement
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Natural Ventilation
• Natural ventilation systems rely on pressure
differences to move fresh air through buildings.
• Pressure differences can be caused by wind or the
buoyancy effect created by temperature
differences or differences in humidity.
27. BUILDING | SERVICES | TWO (BLD60503)
Passive stack ventilation (PSV)
PSV Consist of
Extract grilles at ceiling height
Ducts to terminal at roof
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Passive stack ventilation (PSV)
Types of vent
30. BUILDING | SERVICES | TWO (BLD60503)
Building Regulation
Habitable or
occupiable rooms
located on an
external wall
Requirements
require a window
opening with
permanent
background ventilation
Natural Ventilation System
Non-habitable
rooms in domestic
buildings
Maybe ventilated
mechanically or
by passive stack
ventilation system
31. BUILDING | SERVICES | TWO (BLD60503)
Building Regulation
Rooms with no
openable
windows in non-
domestic buildings
Requirements
Mechnical ventilated
or air-conditioning
Natural Ventilation System
Kitchen,bathrooms
,utility rooms etc
Open window and
mechanical extract
ventilation or by
passive stack
ventilation system
32. BUILDING | SERVICES | TWO (BLD60503)
Mechanical Ventilation System
Artificial methods of preserving the
purity and controlling the temperature
of the atmosphere.
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Mechanical Ventilation System
Method:
Extract
Supply
Combined extract and input
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Extract system
• Cheap to install and operate
• Definite volume of air is removed from
buildings
• Air entering to replace cannot be controlled.
• Draughts are created
39. BUILDING | SERVICES | TWO (BLD60503)
• Air delivered under pressure.
• Include air heater battery with automatic
control over temperature of air delivered
into rooms
• An air filtration device
Supply system
40. BUILDING | SERVICES | TWO (BLD60503)
• Easy to install in existing buildings
• Can be included when designing new
building.
• Eliminates draughts by building up
pressure inside the spaces
Supply system
41. BUILDING | SERVICES | TWO (BLD60503)
Combined supply & extract system with propeller
fans
42. BUILDING | SERVICES | TWO (BLD60503)
Combined supply & extract system with propeller
fans
56. BUILDING | SERVICES | TWO (BLD60503)
Filters
Viscous or Wet
Filter made of
•A bank or rows of
corrugated metal sheets
with surface coated in
non-flammable, non-
toxic odourless oil
66. BUILDING | SERVICES | TWO (BLD60503)
Factors influencing the size of ducts for air
transport are:
The volume of flow rate of the air
The friction of the air against the walls of the
ducts and any turns and protrusions.
The pressure available for the movement of
air.
68. BUILDING | SERVICES | TWO (BLD60503)
Calculation of air volume flow rate:
Q = Room volume x air changes per
hour/time in seconds
Where
• Q is the volume of flow rate in m3/s
Ventilation duct design