Regulating relative humidity in poultry houses

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Maintaining the correct relative humidity (RH) is crucial for animal welfare and productivity in poultry houses because the impact of relative humidity on animal growth and health can be profound. If the RH is too high or too low, the birds may suffer from health issues which can also impact negatively on their performance and growth. Excessive RH will cause wet litter which can result in foot problems and skin disorders. It also promotes the growth of bacteria and moulds, which can cause respiratory problems.

Relative humidity in poultry houses

Humidity, or moisture, in the house is caused by the heating system, leakage or water spilled from the drinkers and by the natural production of vapour when the poultry breathe. Seasonal influences such as the outdoor conditions can cause variations in the relative humidity in poultry houses. In many regions the summer months are characterised by higher temperatures and often higher relative humidity. Warm air can hold more water vapour which increases the relative humidity. The humidity generally decreases during autumn and winter, but periods of high humidity can still occur, especially during rainy periods or when snow melts. 

The optimum relative humidity

It is difficult to state the optimum relative humidity for poultry as an absolute percentage. The range can vary considerably and depends on the life stage of the birds, the type of poultry and the specific climate zone.  It is always advisable to follow the guidelines provided by the hatchery to determine the correct RH values for your house to prevent negative effects of relative humidity on poultry production. 

Climate sensors in a poultry house

How is relative humidity measured

Our climate computers for poultry houses use an RH sensor to continuously monitor the relative humidity in the house, and generate a warning if the relative humidity exceeds the desired limits. These limits are often based on the apparent temperature experienced by the birds as relative humidity strongly influences the perceived effect of wind chill. With high humidity, the environment feels warmer than the temperature actually indicated in °C whereas with low humidity the temperature is perceived as colder. These effects mean the relative humidity must be taken into account when determining the optimum temperature to set for the climate control computer. Generally speaking, climate computers that factor in the relative humidity create a better house climate.

HumiTemp control

Fancom's poultry computers have a special HumiTemp feature. This control enables the climate computer to take the effect of relative humidity into consideration and determine the ideal temperature in °C. If the relative humidity is high, the temperature can be set slightly lower to prevent the birds from perceiving the temperature as too high. If the humidity is too low, the climate computer will set the temperature slightly higher. Thanks to the HumiTemp setting, the conditions in the house will better reflect the actual needs of the poultry. 

Because HumiTemp constantly influences the climate control, there is a continuous transition from high humidity (typically early in the morning) to lower humidity (usually in the afternoon) and the settings for the ideal temperature are gradually corrected.

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Precise ventilation maintains the correct house RH 

Good ventilation is important to maintain the correct relative humidity in poultry houses. Ventilation removes excess water moisture and maintains the relative humidity at an acceptable level.

Increasing the temperature can reduce the RH in the house. The relative humidity will decrease by 4.5 percent for each °C increase in air temperature. As warm air is lighter than cold air, the warmest air is usually found in the ridge of the house. By properly directing the incoming air to the ridge it can mix with the already warm air in the house and therefore reduce the relative humidity.

Impact of too low relative humidity

Problems in the house are not only caused by too high relative humidity, but by too low relative humidity as well. If the air is too dry it can cause respiratory problems and dehydration, increasing the risk of infection. A too low relative humidity may affect the egg production of layers.

Too low relative humidity can occur in hot and dry climate conditions, but also in houses with a heat exchanger. When a heat exchanger is used to warm the house, no water is added to the air. This can cause a significant reduction in the relative humidity. In these situations, it is advisable to use a humidifier. The Fancom Hygrofan is a recirculation fan with an integrated humidifier. The house air is humidified by water sprayed onto the rotating disc. The rotational speed of the disc, combined with its finely serrated edge, produces a mist that is blown into the house by the fan. As the Hygrofan is integrated into the air circulation system in the house, the humidified air is distributed uniformly throughout the building. That makes moisture distribution easy to adjust, even with low volumes. 

Good minimum ventilation is essential for a good climate in the house

This makes it an absolute condition for a top performance from your animals! Sufficient minimum ventilation is essential to extract damaging waste substances such as CO2, NH3, moisture, dust and heat and to introduce oxygen rich air.

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Relative humidity sensor

Effectively coping with varying levels of relative humidity in the house demands a combination of technological solutions, good management and insight into the specific needs of the poultry. Continuous monitoring of the conditions in the house and responding rapidly to changing conditions are crucial to ensure a healthy and productive environment for the birds. This is only achievable with reliable climate sensors that continuously and automatically monitor the house climate. 

And finally, it is also important to regularly inspect the drinking water systems, cooling systems and ventilation system. Periodic maintenance to equipment and installations is vital to ensure optimal functioning.


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