The document discusses ventilation for poultry housing. It explains that ventilation is needed to manage temperature, humidity and air quality for optimal bird performance. It describes different ventilation types including minimum, transitional and tunnel ventilation suited for different weather. Key parameters for fan selection and sizing of fans, inlets, cooling pads are discussed. Potential problems with uneven ventilation or temperature are also summarized if the ventilation system is not designed or operated properly.

1. BY AYESHA AIMAN

2. By
Dr. Naeem Tahir
ASM
Jadeed Sales Office
Faisalabad.
2

3. The bird!
Homoeothermic
Body temperature---------------105-107˚F(41-42˚C)
Upper lethal body temp.-----------------115˚F(46˚C)
Environment comfort zone--------70-75˚F(21-23˚C)
3

4. Where is the most heat coming
from?
18%
ceiling
2%side wall
80%bird
4

5. Methods of heat loss:
Conduction Convection Radiation
5
Higher wind speeds increase sensible heat loss
and reduce latent heat loss in broilers.

6. Objective of Fan System
A System that delivers fresh air into the poultry house
and removes obnoxious gases from the poultry house

7. Fan Operation
At a Glance
Fan System is For
 Moving FRESH AIR INTO a house and moving
STALE AIR OUT of the house;
 Sending UNWANTED heat, EXCESS moisture,
ammonia, OUT of the house; and
 AIR MIXING to get heat, moisture, ammonia INTO
THE AIR that leaves the house.

8. 8
Objectives of Fan Operation
o Maintain uniform temperature
o Provide fresh air
o Remove undesirable gases
o Remove moisture
o Keep the litter dry
o Keep uniform condition in the house

9. What is ventilation ?
Ventilation means moving the right
amount of air at the right time and in
such a way to manage temperature,
humidity and other environmental
factors for optimum bird
performance

10. Types of ventilation:
Minimum ventilation
Transitional ventilation
Tunnel ventilation
10

11. VENTILATION PARAMETERS:
Tunnel fans capacity.
Cooling pads area.
Minimum ventilation fans.
Air inlets.
Climate controller.
Insulation.
11

12. Ventilation
For ventilation purposes
weather can be divided
into three types

13. Weather types
1. Winter
2. Summer / Monsoon
3. Moderate

14. Types Of Ventilation
1. Winter => Minimum ventilation
2. Summer / Monsoon =>Tunnel ventilation
3. Moderate weather =>Transitional ventilation

15. Relative Humidity
Moisture holding capacity of
air at certain temperature.
OR
A ratio of the quantity of water vapor in the
air compared with the total that can be held
at a given temperature
Important Terminology

16. Relative Humidity
 Warm air significantly hold more water
than cold air
 Water holding capacity of air doubles
with each 11oC increase in temperature

17. Important Terminology
Dew Point Temperature
Temperature at which water vapors are
transformed back to liquid

18. Static Pressure
When we run the exhaust fans a
negative pressure is created inside
the house. To measure the
difference of outside and inside
pressure we use the term ‘Static
Pressure’. It is mentioned in Pascal
or inches.

19. CFM
 Volume of air being moved by a fan or
entering an air in let

20. Air inlet & Air jet
 A controllable opening generally located
at the eave controlling the velocity of air
 Air that is allowed to travel adjacent to a
smooth surface, generally a ceiling or
side wall.

21. Throw
 The distance an air jet will travel before
its maximum speed is decreased to 75
feet per min.
 Less than 75 fpm the air moves
aimlessly

22. Measures of Poultry House
 Length 450 ft
 Width 45 ft
 Height 8 ft

23. Fan Calculation
 Volume of House
 Cross Section of House
 Desire Air Velocity
 Fan Capacity

24. Fan Calculation
Volume of House = Length x Width x Height
= 450 x 45 x 8
= 162000 cub. ft

25. Fan Calculation
Cross Section of House
Width X Height
45 X 8 = 360 sq. ft

26. Fan Calculation
Desire Air Velocity
Length of the house
Mostly we recommend (length + 50-75)
500 ft/min
Fan Capacity
18000 cfm
22500 cfm

27. Fan Calculation (1)
Cross Section x Air Velocity ÷ Fan Capacity = No of Fans
360 x 500 ÷ 22500 = 8

28. Fan Calculation (2)
Volume of House ÷ Fan Capacity = No. Fans
162000 ÷ 22500 = 7.2
= 8

29. Air Exchange ≤ 1
Air Exchange = House Vol. ÷ Tot. Fan Capacity
= 162000 ÷ 180000
= 0.9-min

30. Air Velocity Calculation
Air Velocity = Tot. Fan Capacity ÷ Cross Section
= 180000 ÷ 360
= 500 ft/ min

31. Pad Area Calculation
 Pad Size (2``, 4``, 6`` )
 Total Fan Installed
 Air Velocity for Pad

32. Pad Area Calculation
Pad Size Air Velocity
2`` 150 ft/min
4`` 250 ft/min
6`` 350-400 ft/min

33. Pad Area Calculation
Pad Area = Tot. Fan Capacity ÷ Air Speed
= 180000 ÷ 250/400
= 720 sq.ft ( 4``)
= 450 sq.ft ( 6`` )

34. MINIMUM VENTILATION /
WINTER VENTILATION

35. Fan Calculation for Minimum
Ventilation
No. of Fans = _______________________Avg. body weight × No of birds× CFM requirement per kg
CFM of Fan

36. Example
 Avg body weight = 2.5 kg
 Cfm required = 0.5 /kg
 Cfm of fan = 9000
 No. of Fans = (2.5 x 30000 x 0.5)/9000
 No. of Fans = 4.16
 5 fans will be needed for winter
ventilation

37. Operating time for Fan
Operating Time = _______________Total CFM Requirement
Total Fan Capacity

38. Example
 Total cfm requirement = 37500
 Total fan capacity = 9000 x 5 = 45000
 Operational time = 37500/45000=0 .83
= 0.83 x
60 sec
= 49.9 sec
 It means that in 1 min fan should be on for 50 sec
and off for 10 sec.
 To get reasonable operational time, we multiply by 4
50 x 4 = 200
 It means in 4 min fan should be on for 3 min & 20
sec and off for 40 sec

39. Inlet Calculation
 Inlet area (sq. in.) = Total cfm required ÷4
= 37500/4
= 9375 sq inch
= 65.10 sq ft
 No. of Vents = Area Required/Area of Vent
= 65.10/ 1m x 0.4 m
= 65.10/ 3.2808 x 1.3123
= 65.10/4.30
= 15. 13
 16 inlets will be required

41. Inlet Calculation on basis of
CFM
No. of inlets = capacity x average weight x
0.5cfm(per
kg)/2000cfm
= 30000 x 2.5 x0.5 /2000
=18.75
This formula suggests 19 inlets should be
used

42. Transitional Ventilation Fans
Vol. of House x 40 % ÷ Fan Capacity = No.of Fans
162000 x 40 % ÷ 22500 = 2.88
= 3

43. Transitional Inlets Calculation
 For each 10000 cfm we require 15 sq.ft inlet area
 Size of each vent
Length Width Area
46`` 6`` 1.91 sq.ft
46`` 8`` 2.55 sq.ft

44. Transitional Inlets Calculation
No.of fans x capacity ÷ 10000 x 15 = Inlet Area
3 x 22500 ÷ 10000 x 15 = 100.5 sq.ft
Inlet Area ÷ Size of Inlet = No.of Vents
100.5 1.91 52.61 (54)
100.5 2.55 39 (40)

45. Minimum Ventilation Fan
Number of birds in the house
Body weight
Cfm per Kg.
Fan Capacity

46. Minimum Ventilation Fan
No.of birds X B.W. X cfm/kg ÷ Fan capacity
30000 X 1.8 X 0.5 ÷ 9000 = No. of fans
= 3
= 3

47. Side wall Fan spacing
Length of house ÷ (No. of fans X 2) = feet from wall
400 ÷ ( 3 X 2 ) = 67 ft
67 X 2 = 134 ft

48. Side wall Fan spacing
67 134 134 67

49. A B CCC
FansPads
Cool Air

50. Estimated effective temperature reduction
when air temp is 85-90˚F:
Air velocity Bird age
Ft/min 1 week 4 weeks 7 weeks
100 -4 -2
200 -12 -5 -2
300 -22 -10 -4
400 -15 -7
500 -18 -10
50
Air Velocity Bird Age

51. Minimum Ventilation Rates per bird
Week Days Cfm/Bird
1 1-7 0.10
2 8-14 0.25
3 15-21 0.35
4 22-28 0.50
5 29-35 0.65
6 36-42 0.70
7 43-49 0.80
8 50-56 0.90

52. Age (days) Max Airspeed Max Airspeed
(m/s) (fpm)
0 – 14 days 0 - 0.5m/s 0 - 100fpm
14 – 21 days 0.5 – 1.8m/s 100 – 350fpm
Air speed for Young Birds

53. How a bird releases
heat?
 A bird releases excess body heat in 2 ways:
 1. To the air around it – Sensible Heat – 11BTU/kg or 5BTU/lb.
 The cooler the air the greater the amount of heat loss. The warmer the air,
the smaller
 the amount of heat loss
 2. Through evaporation of moisture from respiratory system – Latent
 Heat – 15BTU/kg or 7BTU/lb.
 the amount of heat a bird loses through the
evaporation of moisture off of its respiratory
 system depends on the relative humidity of
the air it breathes

54. 3 Areas Where Broilers Release Heat
1. Head,
2. Legs,
3. Under wing

55. Heat Loss & Air Speed
o Without airspeed evaporative cooling is potentially
dangerous and as air velocity increases, the importance of
relative humidity to a bird decreases
o If the temperature of the air moving over a bird is equal to
its body temperature essentially no heat will be lost to the air. It
is not an either/or situation.
o A producer needs to utilize both air movement and
evaporative cooling during hot weather to keep birds
comfortable and productive.

56. Wind Chill Effect – Effective Temperature
Any wind-chill curve is an estimation!!
– Effective temperature (what a bird perceives the
temperature to be) is a function of:
1. Air temperature
2. RH
3. Bird Age
4. Stocking Density
5. Wind Speed
6. Amount of radiant Heat – roof or side walls
As a result it is very difficult to come up with a chart/formula
that accurately predicts effective temperature!

57. How much does the air heat up?
1. Amount of heat added to the air in a house
the more heat added to the house, the hotter the house will be
2. How quickly we exchange the air in the house.
the faster the air exchange rate, the cooler a house will be
Remove heat from the house by:
rapidly exchanging the air in the house.
If we don’t exchange the air rapidly large temperature
differences can occur between the inlet and exhaust ends of
the house.

58. Fan Timer Setting
Cfm per bird X No. of birds ÷ Fan capacity
0.5 30000 ÷ 27000
= 0.55 (55%)
= 0.55x60= 33 sec.
or
0.55x300=
165 sec. On and 135 sec. Off

59. Tunnel Ventilation

60. Tunnel Ventilation

61. Transitional Ventilation

62. Minimum Ventilation

80. Ventilation with end fans side inlets

81. Side inlets and side fans

85. Potential problems:
 Not uniform temperature in the house:
 Proper insulation of the house.
 First go on tunnel ventilation, then
cooling.
 Increased heating cost:
 Center house brooding.
 Proper insulation.

86. Potential problems:
 Uneven ventilation:
 Excessive leakage near the
 pads area,
 doors,
 windows, and air inlets.
 Litter caking :
During Winter:
 Improper minimum ventilation.
 Requires proper air inlets opening along with proper no. of 36”
fans.
During Summer:
 Low air movement.
 Proper ventilation. (First go on tunnel ventilation, then cooling).
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