Shed cooling system

Performance goal: Shed cooling (evaporative cooling and fogging) systems provide shed cooling without causing a risk to meat chicken health.
Description: The rapid growth of modern meat chickens is associated with increased susceptibility to heat stress. Modern Australian meat chicken sheds usually have fogging and/or evaporative cooling systems to maintain optimal shed temperature. Relative humidity, location and environmental conditions must all be considered when selecting the most suited cooling system for a specific meat chicken farm.
Performance criteria: Adequate coolers are installed in sheds to maintain the optimal temperature for chicken performance. See Tables 25 and 26 (below) for optimal temperature recommendations.
Minimum requirements
Water for cooling comes from sources that have been treated to drinking water standards.
Regular maintenance – coolers are flushed and cleaned as per the manufacturer’s recommendation.
Birds cannot access to cooling water. Stored cooling water is protected in the supply tank or sump recovery from direct sunlight to reduce algae growth.
Online temperature, relative humidity and ventilation are monitored.
Automatic and remote cooling system control.
Evaporative cooling pads: Cooling pads (compared to foggers) usually work best when temperatures need to be lowered in high-humidity conditions. Monitor relative humidity carefully when in operation. Pad space surface area must match the fan capacity to ensure correct airflow and evaporation. Pad area should always be in line with the tunnel inlet opening. The cool pad house should be a minimum of 0.6–1 m wide to allow for easy access for maintenance and cleaning. The water recovery system must be above ground to ensure easy access for maintenance and cleaning. Large evaporative pads should have booster pumps to ensure water distribution across the pads. Avoid placing any structures or shading in front of cooling pads that will cause a pressure increase.
Fogging systems: Foggers (compared to cooling pads) are a better option when you need to cool down drier areas, where the air can absorb more moisture. Monitor relative humidity carefully when in operation. Install the fogging lines in a loop throughout the shed. The location of foggers depends on the shed and ventilation system. High pressure = low water use, low pressure = high water use – i.e. a balance between pressure and flow. High pressure is usually associated with higher costs for pumps, pipes and running costs. However, it uses water more efficiently. Install an automatic drain valve on each line to drain the water to the outside of the shed when the pump is off. The pump is controlled by both temperature and humidity. Foggers start running at 28°C. Moisture is never directly added to the inlet opening when the air velocity is more than 3m/s. The inlet area fogging nozzles are positioned where the air velocity is under 3m/s to prevent floor and bird wetting.
Best practice options
Flow meter installed on cooling systems determine water used for cooling.
Foggers and their water lines are flushed and sanitised after each batch. If water is hard, foggers and lines are treated with an additional de-scaler.
High-pressure water foggers are used.
Evaporative cooling pad: Pads must be allowed to dry out once each day. If algae growth is a problem, an algicide is used in the water supplied to the cooling pads. Pads are be washed monthly to remove dust and sediment. The entire system is flushed monthly to remove the mineral salts and dirt that accumulate in the pipes and reservoir.

Other information

Table 25. Temperature curve based on House Relative Humidity Guidelines (reproduced from Cobb, 2018)

Bird age or stocking density	Relative humidity
	30%	40%	50%	60%	70%
0 days	34°C	33°C	32°C	31°C	30°C
7 days	32°C	31°C	30°C	29°C	28°C
14 days	29°C	28°C	27°C	26°C	25°C
28kg/m²	25°C	24°C	23°C	22°C	21°C

Table 26. Temperature guide based on stocking density (reproduced from Cobb, 2018)

Density (kg/m²)	Target temperature (°C)
28	22–24
30	21–23
32	20–22
34	19–21
36	18–20
38	17–19
40	16–18
42	15–17
42+	14–16

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