Management of Poultry House Ventilation by Dr.Muhammad Ashiq Toor

2. Dr MuhammadAshiq Toor
DVM , B s c (Zoology)
Islamia University of Bahawal Pur (IUB) (2010 – 2015)
+92-344-499-7375
+92-300-364-2402
Managing Poultry House Ventilation

3.  Generally divided into two types:
 (1) Natural air flow system
 Natural air currents are allowed to enter into the
house.
 Fit for areas where outside temperature does not
exceed 33°C.
 House width may be maximum around 30 feet for this
system.
 Conventional farms are built on this principle
 (2) Mechanical air movement (fans).
 Mechanical systems use electric fans as principal
components to exchange air in the building. They can
be divided into two distinct types(Positive pressure
and negative pressure).

4.  In the positive pressure system, fans are
arranged to push fresh air in to the building.

5.  In the negative pressure system, fans are
arranged to expel air from the building. In
doing so, they create a partial vacuum or
negative pressure inside the house. The
pressure difference pulls fresh air through
inlets into the house.
 The location, distribution and size of the fans
and inlets are critical if all areas of the house
are to be ventilated.
 We may term this system best fit for our
climatic conditions.

6.  To discuss this system in changing climatic
conditions we may mainly divide it in to;
 1-Cold Weather Ventilation (Minimum
ventilation)
 2-Hot Weather Ventilation (Tunnel
ventilation)
 3-Optimum weather ventilation
(Transitional ventilation)

7.  Minimum ventilation is used to provide fresh air
inside the house during cold weather. It removes
excessive moisture and minimize the heat loss.
 Fans exhaust air out of the house by creating a
slight negative pressure inside the house. Due to
the negative pressure, fresh air is pulled into the
house through some planned air inlets.
 The air inlets are installed either in the ceiling or
high on the house side wall. These inlets are
designed to direct air across the ceiling allowing
it to mix with warmer air located there and to
heat up before coming into contact with the
birds.

8.  Most important tools are exhaust fans and air
inlets(vents) and other accessories to operate
fans and vents properly.

9. Exhaust fans
Expel air out of
the building. In
market there are
different types of
fans available with
varying capacity.
Normally for
minimum
ventilation 9000
CFM capacity fans
are used but we
may also use fans
of any capacity.

10.  Though this topic belongs to tunnel ventilation but
to ensure continuity we have to discuss # of fans to
be installed in a house first. Formula to calculate
number of fans is as follows.
No Of Fans = Cross Section x Desired velocity
CFM of one fan
 (Cross section= width * height of the house)
 Desired velocity in our climatic conditions must be
more than length of the house to get less than 1
minute air change.
 CFMs of air expelled by a single fan depends upon
the size and efficiency of fan recommended by the
manufacturer.

11. Controllers: It is an
electronic device that
collect information from
different sensors and
execute scheduled tasks.
Static pressure switch
provide information to
controller and controller
operates power track to
open or close vents
accordingly.

12.  Area for vents=Total no of fans x cfm of one fan x 40%
700 f.p.m
 Total no of vents=total area for vents
Area of one vent
 (40% of total ventilation is maximum limit of
minimum ventilation).
 (Air should pass across the vent at a speed of 700
fpm).
 We can purchase vent of any dimension from
market. Greater the area of vent, Less would be the
number of vents and vice versa

13. Static pressure sensor:
sensor is installed with
controller to sense static
pressure and give feed
back to controller so that it
may open or close the vent
according to static
pressure to avoid chilling.
Power track : it is an electrical
device attached mechanically
to vents and on the
information of controller,
Operates the vents according
to the static pressure.

14.  Tunnel Fans : Off
 Min. Ventilation Fans : on
 Cooling Pad : Closed
 Vents : Open
 Evaporative Cooling : Off
 Tunnel door : Closed

15.  Knowing how much to ventilate during cold
weather minimum ventilation value of 0.588 cubic
feet per minute per kg body weight is suggested.
Ventilating too little can lead to poor air/litter
quality, resulting in bird health and performance
issues. Ventilating too much can lead to drafty
conditions and high heating costs.
 Static pressure is of importance to avoid chilling
and its desired value is dependant upon width of
house. As a rule of thumb the width of house in
meters is equal to the static pressure required in
Pascal.

16.  Calculate total live weight in house by
multiplying average weight in kilograms with
number of birds present in house.
 By multiplying total live wt with 0.588, we will
have total cfms required to ventilate house.
 Adjust the fan runtime by dividing total cfms on
cfm of one fan.

17.  Lets say width of house is 45 feet.
 Divide 45 by 3.2808 to convert it into meters.
 45/3.2808 gives 13.71.
 So 13.71 Pascal pressure is required.
 Divide 13.71 by 249 to convert it into inches
of water column.
 So 0.055 inches of water column static
pressure is required to pull the air up to the
center of house.

18.  Let suppose we have a house of Length 500 ft, Width
45 ft, Total number of birds are 40,000 and average
weight of the bird is 500 grams. Capacity of one
minimum ventilation fan is 9000 CFM. Outside
temperature is 2 Degree Centigrade. How to calculate
its ventilation?
 Calculation of minimum ventilation:
 40,000 x 500= 20,000 kilograms
1000
 20,000 x 0.588= 11760 CFM required
 11760 = 1.30 Fans
9000

19.  1.30 fans mean that we may operate one fan
continuously and one fan on 30% timer. We
may also operate 2 fans on 65% timer or
operate 3 fans on 43% timer.
 Static pressure:
 45 / 3.2808 = 13.71 Pascal
 13.71 / 249 = 0.055 inches of water
column(1’’ of water column =249 Pascal)

20. Age wise recommended
minimum ventilation Per Bird
rates.
Some studies recommend
typical minimum
ventilation rates per bird
depending upon the age
of the broilers.

21.  Fall and spring are transitional seasons when
difference between day and night temperature may
range from 15 to 20 degree centigrade. So this is a
difficult time for farmers to manage poultry house
ventilation.
 Farmer must be alert to need for ventilation setup
changes and manage the transition smoothly.
 Transitional ventilation goal is to maintain in house
optimum temperature that support best bird
performance.
 In transitional weathers wind chill is required at day
time but may hurt bird performance at night. So keep
on switching between minimum and tunnel
depending upon outside temperature is necessary.

22.  Transitional ventilation fills gap between hot
weather and cold weather ventilation needs.
 Maintaining in house temperature that
support best bird performance during
changing weathers.
 Switching between minimum ventilation and
tunnel ventilation to get wind chill when
required in any part of day and stopping
when required.
 Switching between side wall fans and tunnel
fans as required.

23.  Side wall fans
 Tunnel fans
 Inlets/vents
 Static pressure switch
 Temperature sensors
 Controllers
 Power track
 Tunnel doors
 Tunnel air inlets

24.  Tunnel Fans : Occasionally On
 Min. Ventilation Fans : On
 Cooling Pad : Occasionally Open
 Vents : Occasionally Open
 Evaporative Cooling : Off
 Tunnel door : Occasionally Open

25.  For keeping the birds cool during hot weather,
we use tunnel ventilation.
 Tunnel ventilation system in the broiler house
consists of large air inlets at one end and fans at
the opposite end. The fans used in one end pull
air the length of the house at a velocity of 500 ft
per minute or more.
 This system removes excessive heat from the
building very fast and make a wind chill that
provides the birds additional cooling.
 Evaporative cooling system is also used for
cooling the house, when tunnel ventilation
system alone is not sufficient enough.

27.  Main goal of Tunnel ventilation is cooling
birds.
 Maintain end to end temperature difference
as low as possible.
 Maintaining low humidity during extreme hot
and humid weather.
 Get rid of immense heat dissipated by the
birds.
 To obtain wind chill effect as per requirement
of the birds.

28.  Tunnel Fans : On
 Min. Ventilation Fans : off
 Cooling Pad : Open
 Vents : Closed
 Evaporative Cooling : On
 Tunnel door : Open

29. Exhaust fans:
Expel air out of the
building and combination
produces velocity of air in
the house.
Number of fans are
determined through cross
section of the house and
desired velocity.
No of fans = Cross Section x Desired Velocity
CFM of one fan

30.  Cooling pads: it is a pad
made up of cellulose with
different flute angles.
When we pour water
upon pads and air pass
through the wet flutes,
air cools down due to
addition of humidity.
That cooled air is pulled
in a single direction by
exhausts fans through
out the house.
 Air velocity across the
pad must be 350fpm
with operation of all fans.

31. When we have desired # of fans what may be the pad area
to support these fans properly in extreme hot weather.
Area of cooling Pad= Total no of fans x CFM of one fan
350 fpm
Total No of pads=total area for pads
Area of one pad
 (Air should pass across the cooling pad at a speed of
350 fpm).
 Number of pads may be determined by dividing total
area required by area of 1 pad.

32. End to end temperature
difference
•In tunnel ventilation end to end temperature difference
must be as low as possible.
•Higher the air velocity lower would be the end to end
difference.
•In the given diagram the end to end difference is almost
2 degree with an air velocity of 550 fpm.

33. Thank You
For
Attention.