Environmentally controlled (EC) poultry shed

An environmentally controlled (EC) poultry shed is a fully enclosed, insulated, windowless poultry house in which temperature, humidity and ventilation are managed mechanically. EC houses are the dominant choice for large commercial broiler integrators and modern layer farms in tropical climates because they decouple bird welfare from outdoor weather, deliver more uniform performance and permit higher stocking density than open-sided sheds (Open Poultry Shed).

Principle

The shed operates under negative pressure: rows of large exhaust fans at one end pull air out of the building, drawing fresh air through inlets at the opposite end. The result is tunnel ventilation with air moving lengthwise across the birds at approximately 500 feet per minute (about 2.5 m/s). High air velocity removes metabolic heat and ammonia and produces an effective wind-chill of several degrees below the air temperature, which protects market-weight broilers from heat stress.

Implementation

A typical EC house is 100-150 m long and 12-18 m wide, with insulated wall and roof panels (50-100 mm polyurethane or rockwool sandwich) to limit solar heat gain. Tunnel inlets at the upwind end carry evaporative cooling pads — cellulose paper honeycombs continuously wetted by recirculating water — that drop incoming air temperature by 8-12 degF (4-6 degC) during the hot season. Light intensity, photoperiod, fan staging, pad pump and emergency-curtain drops are sequenced by an environmental controller responding to temperature and ammonia sensors. Diesel generators back up power, since loss of ventilation in a sealed shed can cause complete flock loss within an hour.

Adoption context

EC houses are paired with high-genetic-merit broiler (Broiler Chicken) and layer strains where the heat-stress penalty in open housing offsets the higher capital cost. They give consistently lower mortality and better feed conversion ratio (Feed Conversion Ratio) than open-sided sheds, and they support higher stocking density (often 13-15 birds/sq m for broilers vs 8-10 in open sheds). Contract-broiler integrators (Contract Broiler Farming) increasingly require EC housing in new agreements. EC infrastructure also works with three-tier cage systems (Three Tier Cage System) for layer farms.

Limitations

Capital cost is two to three times that of an open-sided shed of equivalent capacity, and operating power demand for fans, pads and lighting is significant. Power outages without standby generation are catastrophic. In moderate-climate inland regions where summer heat is shorter, conventional ridge-and-side-vent open-sided sheds with adequate roof height (Shed Height Ventilation) can deliver comparable economics with lower exposure.

References

Environmental Management in the Broiler House. Aviagen.
Tunnel-Ventilated Sheds with Negative Pressure Reduce Thermal Stress. PMC.