The document discusses poultry house ventilation, highlighting its importance for providing fresh air, controlling temperature and humidity, and minimizing air contamination for chickens. It details various ventilation systems, such as natural airflow and mechanical air movement, along with their components, design principles, and the importance of insulation. Additionally, it emphasizes the need for regular maintenance and monitoring to optimize the health and productivity of poultry in confined environments.

1. POULTRY HOUSE VENTILATION
ROTEM SYSTEM

2. WHAT IS VENTILATION
• Ventilation in a poultry house supplies fresh air
that is essential to sustain life. It also helps
reduce the extremes of temperature, humidity
and air contamination to tolerable limits for
confined chickens.
Improved ventilation systems have also made
possible the high density populations of livestock
and poultry in confinement, thus reducing the
building cost per unit housed. This is
economically important since it reduces
production and labour costs.

3. • Ventilation air removes excess heat, moisture,
dust and odours from the building and, at the
same time, dilutes airborne disease organisms.
Properly designed winter systems also conserve
energy by utilising heat generated by the birds.
Providing proper ventilation to poultry is an art
but it can be mastered by any determined and
willing poultry grower. It is a challenge, however,
since poultry houses are different and ventilation
requirements change with time of day, season,
temperature, humidity, wind, bird age and
density.

4. PRINCIPLES OF VENTILATION
• f air is not replaced in an enclosed building where
poultry is confined, the air composition changes. The
concentration of carbon dioxide, ammonia and other
harmful gases will increase to unacceptable levels.
Table 1 indicates the level of some of the gases that
research has shown to be critical and the level that is
desirable. As the ventilation system exchanges the air
in the building, it brings in the oxygen needed to
sustain life and carries out the harmful gases and
undesirable odors caused by respiration and waste
decomposition The system also dilutes airborne
disease organisms and keeps them at a tolerable level
for the birds’ health.

5. COMMON GAS LEVELS IN POULTRY
HOUSE
GAS SYMBOL LETHAL DESIRABLE
CARBON DIOXIDE CO2 ABOVE 30% BELOW 1%
METHANE CH4 ABOVE 5% BELOW 1%
AMMONIA NH3 ABOVE 500PPM BELOW 40PPM
HYDROGEN SULFIDE H2S ABOVE 500PPM BELOW 40PPM
OXYGEN O2 BELOW 6% ABOVE 16%

6. • Ventilation must be used to remove excess
moisture from the house. Proper ventilation
reduces relative humidity, promotes health and
prevents moisture from condensing on the walls
and ceiling. When heated, air expands in volume
and can hold more moisture. The moisture-
holding capacity of air doubles each time the air
temperature is raised approximately 20°F.
(Figures 1 and 2). This characteristic helps remove
moisture from houses during cold weather.

7. MOISTURE REMOVAL THROUGH HEAT

8. MOISTURE HOLDING CAPACITY OF AIR

9. BUILDING INSULATION
• Insulation can dramatically affect the level of
supplemental heat and ventilation requirements. It
reduces heat losses or gains through the walls and
ceiling, controls condensation and reduces the
supplemental heat requirements. The effectiveness of
insulation is measured by its R-value. The higher the R-
value, the more effectively the insulation reduces heat
transfer. The optimum amount of insulation for poultry
housing depends on numerous factors, such as its cost
in relation to fuel cost and local climatic conditions.
Because of these factors, optimum insulation levels
vary for every situation.

10. • Most insulation products need to be protected
with a vapour barrier. Wet insulation loses its
effectiveness and does not regain its original
insulation value when it dries. Structural
framing in insulated walls can also be
damaged without adequate vapor barriers.
Place vapour barriers on the inside surface of
the insulation

11. VENTILATION SYSTEMS
• Ventilation systems are generally divided into two
types:
• (1) natural air flow system and
• (2) mechanical air movement (fans).
Because of varying ventilation requirements, the
two distinctly different systems are sometimes
combined in an attempt to provide comfort to
the chickens during varying climatic conditions at
minimum cost.

12. MECHANICAL VENTILATION SYSTEM
• Mechanical air movement is required to properly
ventilate a house in all extreme climatic
conditions.
These mechanical systems use electric fans as
principal components to exchange air in the
building. They can be divided into two distinct
types:
• (1) negative pressure and
• (2) positive pressure.

13. NEGATIVE(EXHAUST) SYSTEM
• 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
poultry house (Figure 1). Distribute inlets
uniformly around the perimeter of the building.
The location, distribution and size of the fans and
inlets are critical if all areas of the house are to be
ventilated. Design specifications are available
from equipment manufacturers and Extension
engineers.

14. FIGURE 1

15. • The location of the fans and air inlets depends
upon the width of the building. For buildings
up to 40 feet wide, place the fans in one
sidewall. Fans on the sidewall opposite the
prevailing wind will reduce back-pressure on
the fan. The fans provide much better
ventilation if they are spaced uniformly along
the wall. Buildings more than 50 feet wide
need fans on both sidewalls.

16. • Air inlet size is critical to proper functioning of
the ventilation system. The air inlet velocity
must be high enough to ensure fresh air
reaches all portions of the facility. However,
the air velocity must not be so high that the
birds are subject to draughts. Install inlets so
air enters and moves toward the ceiling. This
arrangement allows the cold ventilating air to
be tempered somewhat by mixing with the
warm air already in the house before it comes
into contact with the birds. This helps reduce
draughts.

17. • Uniform air distribution in the poultry house
can only be ensured if the building is airtight
except for the properly sized, uniformly
spaced air inlets. Leaks around doors and
around other openings in the walls or ceiling
must be stopped. For these reasons, as well as
a tendency to short circuit, pressure systems
are difficult to manage in curtain-sided
houses.

18. POSITIVE PRESSURE SYSTEM
• A positive pressure system uses fans to push air
into the building and create a positive pressure.
The pressure difference causes the air to move –
in this case out through louvres or other outlets.
A number of positive pressure systems are used
in the poultry industry. One system pushes warm
air into the house and mixes it with inside air
throughout the house. In another type, the warm
air is pushed the length of the house through
plastic tubes or ducts with outlets. This system
distributes heat and mixes air in the poultry
house.

19. MIXING OF VENTILATION AIR
• Simply passing air through the building does
not ensure proper ventilation (Figure 4).
Proper ventilation introduces fresh air
uniformly, mixes it well with house air and
circulates it properly through the house.

20. IMPROPER AIR MIXING

21. • If old air is allowed to flow into a warm area
without direction or velocity, it will cause fog
and/or create draughts on the birds. In the
summer the air must be given controlled
direction to ensure uniform air distribution and
prevent ‘dead air’ pockets.
Place fans near the ceiling down the centre of the
house and on the extreme ends of the house to
circulate and mix the air. The fans mix the air
within the house to prevent warmer air from
remaining near the ceiling.

22. • The supplemental heat requirements for broiler
housing vary with the insulation level, ventilation
rates, outdoor temperatures and management
practices. The addition of supplemental heat
allows the operator to maintain desired
temperature levels during cold weather and while
the birds are young.
Mixing and circulating the air in enclosed houses
during cold weather utilizes heat generated by
the birds to reduce supplemental heat
requirements and keep litter dry.

23. COMPONENTS OF A MECHANICAL
VENTILATION SYSTEM
• A ventilation system has three principal
components:
• (1) the fans required to move the air through
the building,
• (2) air inlets and outlets and
• (3) a set of controls (thermostats and timers)
to regulate fan operation.

24. • In selecting fans for a specific ventilation system,
the wide range of climatic conditions must be
considered as well as the ventilation system
under which they will be used.
• Generally speaking, it is better to select oversized
rather than undersized fans to supply the
required ventilation. A safety factor is provided in
case any one fan fails to operate. However, you
can save money in both initial and in operating
costs by using correctly sized fans. Operating
costs can be reduced by using efficient motors on
the fans.

25. INLETS AND OUTLETS
• The rate of air exchange is determined by the
fans but the uniformity of air distribution
depends primarily on the location, design and
adjustment of the air inlets.
Air inlet velocities of 600 to 1,000 feet per
minute (fpm) are recommended. A good rule
of thumb for sizing inlets to achieve this
velocity range is

27. • Since ventilation requirements change with
bird age, body weight and outside
temperature (Table 2), slot widths have to
change also. Typical slot width ranges are
between one and six inches. Widths can be
controlled either manually or with static
pressure sensitive automatic controls.

28. CONTROLS
• Fans are usually controlled by thermostats or
thermostats in combination with interval timers. A
single stage thermostat will control one or more single
speed fans by activating the fan when the temperature
rises and stopping it when the air temperature drops to
a selected level. A thermostat with a double throw
switch will control a two-speed fan, automatically
changing from high to low speed as temperature
changes to a selected level. Fans with motor-operated
shutters should be controlled by the same thermostat
to ensure their simultaneous operation.

29. • The interval timer permits intermittent operation of
one or more fans because the fans are not usually
operated continuously in cold weather. Most timers
operate on a 10-minute cycle to approximate the air
delivery of a continuously operating fan. A
continuously operating fan providing the proper
amount of ventilation air would not provide the air
velocities required for proper mixing. A thermostat
interconnected with the timer overrides the system
when more ventilation is needed to remove excess
heat.
Relays are necessary to protect the motors and
thermostats when a group of fans are to be controlled
simultaneously by a single thermostat or timer.

30. GENERAL REQUIREMENT FOR EFFECTIVE INSTALLATION
• Design the system with extreme climatic conditions of the area in mind.
• Follow the design and specifications when you install the ventilation equipment.
• For system balance, the building should be filled with birds to the designed
capacity.
• Insulation of the structure must be based on the intended use and local weather
conditions.
• Insulation should be of the proper type and installed so as to be protected from
rapid deterioration.
• Clean the ventilation system regularly and adjust it seasonally.
• Provide supplemental heat and cooling for extreme climatic conditions.
• All equipment (fans and controls) should be serviced periodically and maintained
in good condition.
• Provide good management for the poultry, the building and the ventilation system.
• A suitable alarm system and/or stand-by electric generating equipment should be
available in case of power failure.

31. ROTEM SYSTEM
• Computerized electronic controllers such as
the Platinum enable farmers to raise high
quality poultry by controlling the environment
accurately and simply. For example, instead of
struggling with individual thermostats for heat
zones and ventilation, Platinum brings these
functions together into one convenient place.

32. FRONT PANNEL