As chicken broilers grow, they produce gaseous waste products which accumulate and have a harmful effect on the quality of air in a broiler house. The main contaminants are dust, ammonia, carbon dioxide, carbon monoxide and excess water vapour. If the ventilation system allows these to reach unacceptable levels then they can be directly harmful to the birds.

There are three systems used in the production of broiler meat.

1 Naturally ventilated open-sided houses;

2. Open-sided houses with extractor fans;

3 Forced fan ventilation.

Naturally ventilated houses

These houses are built in well-drained and naturally ventilated locations, preventing direct sunlight penetrating houses during the hottest part of the day. Orientation should be east–west lengthwise. A high roof pitch of 30–40 degrees aids in natural ventilation and height of the building reduces radiation of heat from the underside of the roof reaching the birds.

The goblin type roof and the open side would be used to control the environmental conditions of the house.

Open-sided houses with extractor fans

This category of house is similar to the previous, but with the addition of free-standing or cooling/extractor fans and possibly with water fogging system for use in reducing heat stress. Fans should be provided at the rate of one/1,000 birds and be thermostatically controlled in appropriate blocks or sections. The fan should be angled down five degrees to actually blow the breeze onto the birds.

Tunnel ventilation: forced fan ventilation

Modern poultry production gives rise to this system. A controlled environment for birds is the latest technology to guarantee food security.

This is known exclusively as tunnel ventilation system. Essentially, air is drawn by the electric-powered fans over the bird in a manner to achieve controlled, effective ventilation. Air speed is calculated to ensure correct ventilation of the floor area; such systems employing exhaust fans are referred to as negative pressure systems.

Tunnel systems consist of banks of extractor fans located at the rear end of the poultry house, extracting downwind. At the other end (front) of the house are inlets. The inlets are fitted with evaporating cooling pads over which passes re-circulated water, which in hot weather is used to achieve evaporative cooling. The system also gives the birds the benefit of the wind chill effect. Installations of timer-controlled fans enable the house to achieve minimum ventilation rate when weather is cold in the same controlled manner.

With the use of a computer, this system will monitor the environmental conditions for you. If the system malfunctions in terms of fans or cooling, then the system automatically lowers the curtains and opens the inlets to facilitate cool air coming in.

— Ebony Park HEART Academy