Natural ventilation, Artificial ventilation, Air conditioning

1. BASIC CIVIL ENGINEERING
Building Ventilation
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2. BUILDING SERVICES
 Building Services are the systems installed in a building
to make occupant comfortable, functional, efficient and
safe.
 The building services might include-
ventilation, air conditioning, water supply, drainage,
plumbing, electrification etc.
 These are basic building services those are both basic
and vital for the daily running of building.
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3. 1.VENTILATION
 Ventilation may be defined as the process of supplying
fresh air from outside into a room & removing used up
air from inside the room
 Ventilation is the continuous process of admitting fresh
air and removing vitiated air.
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4. NECESSITY OF VENTILATION
 To create air movement so as to remove the vitiated air
or replace it by fresh air.
 To prevent and undue concentration of bacteria carrying
particles.
 To prevent and undue concentration of body odour,
fumes, dust & other industrial by products.
 To prevent flammable concentration of gas vapour or
dust in case of industrial building.
 To remove product of combustion & in some cases
to remove body heat & heat librated by the electrical
and mechanical equipments 4

5. TYPES OF VENTILATION
 The system of ventilation is basically divided into two
groups-
I. Natural ventilation or aeration
II. Mechanical or artificial ventilation
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6. NATURAL VENTILATION
 It is also called as aeration.
 Natural ventilation is the process of supplying fresh air
to and removing air from an indoor space without using
mechanical systems.
 In turn, this fresh air helps force the warm, dirty air
inside of the building out through the opening in the
roof.
 Natural ventilation is generally considered suitable for
houses & flats (i.e. for small buildings) and not suitable
for big offices, large factory or workshop.
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7.  Points considered while providing natural ventilation-
a) Doors and windows should be located to provide the
maximum inflow of air.
b) The height of building should be sufficient to allow air
movement.
c) Inlet opening should not be obstructed by trees,
partitions etc.
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8. MECHANICAL OR ARTIFICIAL VENTILATION
 In this system of ventilation some mechanical
arrangement is adopted to provide enough ventilation
to room.
 The outside air is supplied into building by positive
ventilation.
 If the supply of outside air is by means of mechanical
devices such as fan then it is termed as positive
ventilation. And for this purpose centrally located
supply fan of centrifugal type is used.
 The process of removal of the air & its disposal
outside by means of device is termed as exhaust of
air. and for this purpose wall or roof located exhaust
fans of propeller type are used.
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9.  Centrifugal type fan
 propeller type fan
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10. METHODS OF MECHANICAL VENTILATION
A. Extract or exhaust system
B. Supply or Plenum system
C. Combination of exhaust and supply system
D. Air conditioning
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11. A. EXTRACT OR EXHAUST SYSTEM
 In this system partial vaccum is created inside the
room of exhausting or removing the vitiated inside
air by means of propeller type fans.
 The extraction of air from inside permits the fresh
air to flow from outside to inside& thus it is possible
to provide fresh air to room by doors and windows.
 This system is more useful in removing smoke,
dust, and odour etc. from kitchen, latrines, industrial
plants etc.
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12. B. SUPPLY OR PLENUM SYSTEM
 In this system the space is filled with air by means
of fan but no special provision is made to remove it.
 In plenum ventilation the air inlet is selected inside
of building where the air is purest.
 In this opening the screen or filters may be fixed &
a fine stream of water may be impugned in the path
of incoming air.
 The disinfection of incoming air is achieved by
adding ozone @ the point of inlet.
 These ventilation systems are costly and are used
for factories , big offices , theatres etc.
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13. C. COMBINATION OF EXHAUST AND SUPPLY
SYSTEM
 This is also called as balance system
 As the name indicates it is the combination of
supply system and exhaust system.
 It uses input fans and exhaust fans to supply and
extract the air inside the room.
 This system gives better result as it enables full
control over air movement.
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14. D. AIR CONDITIONING
 This is most effective system of artificial ventilation
in which provision is kept for humidifying , heating,
cooling & filtration etc. Of the air to meet the
possible requirements.
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15. FUNCTIONAL REQUIREMENTS OF VENTILATION
SYSTEM
1. Rate of supply of fresh air-
 the quantity of fresh air to be supplied is depends
on the use of building
 supply rate is decided by considering several
factors like no. Of occupants, period of working, age
of occupants etc.
2. Temperature of air-
 The incoming air of ventilation should be according
to need of climate (i.e. Incoming air should be cool
during summer and hot during winter.)
 Inside and outside temp. difference should not be
greater than 8 degree cel.
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16. 3. Humidity-
 The relative humidity within the range of 30 to 70%
@ a working temp ( 21)is considered as desirable .
 When working is required to be done at high temp.
low humidity & greater air movements are
necessary for removing greater portion of heat
from the body.
4. Purity of air-
 it is essential that the ventilated air should be free
from the impurities such as odour, organic matter,
dust & unhealthy fumes of gases like CO, CO2
 Impurities depends on habits of occupants ,
volume of room, surrounding conditions etc.
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17. 5. Air movement-
 At the building where peoples are working the air
has to be changed or moved to cause proper
ventilation.
 The rate of change will depends on the volume of
structure, type of activity in premises, no. Of
persons in premises , velocity of fresh incoming air,
the quantity of heat , moisture and odour in a room
.
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18. 2.AIR CONDITIONING
 It may be defined as the process of treating air so
as to control simultaneously its temp. Humidity,
purity& distribution to meet the requirements of
conditioned space.
 The requirements of conditioned space may include
comfort and health of human beings, need of
certain industrial processes, efficient working of
commercial premises.
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19. PURPOSE OF AIR CONDITIONING
 It helps in preserving and maintaining health,
comfort and convenience of occupants of
residential building.
 In commercial premises such as theatres , bank,
shops it is done to improve working condition &
maintain comfort.
 It helps in improving the quality of products in
certain industrial processes such as artificial silk,
cotton cloth etc
 In other cases of industries it provides comfortable
working conditions for workers resulting in increase
in production. 19

20. CLASSIFICATION OF AIR CONDITIONING
1. Classification based on season-
 Summer air conditioning
 Winter air conditioning
 Composite air conditioning
2. Functional classification-
 Comfort air conditioning
 Industrial air conditioning
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21. CLASSIFICATION BASED ON SEASON
1. Summer air conditioning-
• In summar outside temperature is more than inside temp.
Hence cycle of operations involved air cooling,
dehumidifying,air distribution and air cleaning.
• 2. Winter air conditioning-
• In winter outside temp is less than inside temp.and hence
cycle of operations involves air heating, humidification, air
distribution and air cleaning.
• 3. Composite air conditioning-
• In this air conditioning required to be done for the whole
year irrespective of the outside temp. Variations hence the
cycle of operation involves humidifying together with air
distribution and air cleaning. 21

22. Cycles of operations in air conditioning-
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23. FUNCTIONAL CLASSIFICATION
 1. Comfort air conditioning-
 This system aims at giving maximum human
comfort to the occupants of the conditioned space.
 2. Industrial air conditioning-
 In this system such a atmosphere conditions are
created ,controlled and maintained that are best
suited to the needs of industry during material
processing , manufacturing, storage etc
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24. PRINCIPLES OF COMFORT AIR CONDITIONING
1.Temperature control-
 comfortable zone- temp. Range which is suitable
for most of the peoples.
 The comfortable zones are different for summer
and for winter due to different clothing worn in two
seasons and due to changes in body.
 The effective temp zones for summer and winter
ranges between 20°C-23°C & 18°C-22°C.
 A temp of 21°Cto 22.5°C is required for comfortable
conditions regardless of outside temp.
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25. 2. Air velocity control-
 high velocity of conditioned air may causes greater
temp. Difference between outside & inside
 A velocity of 6 to 9 m/sec is considered as desirable.
3. Humidity control-
 In case of winter air conditioning is humidification( i.e.
Addition of moisture to heated air)
 In case of an summer air conditioning is dehumidification
(i.e. extraction of moisture from cooled air)
 During summer season 40-50%and for winter season
50-60% is most comfortable.
 Avg value of relative humidity between 40-60% is
desirable.
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