Identity

A hybrid structural configuration that bridges the gap between passive natural ventilation and fully sealed mechanical environmental control. It utilizes a dual-mode environmental strategy, acting as an open-sided shed during moderate weather and shifting to negative-pressure mechanical cooling via lateral curtains during heat waves.

Overview

The Semi-EC House, also known as a curtained tunnel, is an intermediate housing structure well-suited for transition zones and contract farming networks. It relies on manually or automatically adjusted curtains combined with evaporative cooling pads and forced air to manage internal climates. This allows the system to effectively handle moderate heat stress in the flock at a fraction of the capital cost of fully enclosed systems.

Structured Facts

Classification

Hybrid Mechanical-Natural System / Environment-Controlled (EC) Housing.

Purpose

To mitigate environmental volatility at a moderate capital cost and handle moderate heat stress during hot seasons.

Design & Construction

Architecturally constructed with standard widths ranging from 10.0 to 12.0 meters, allowing for a higher structural capacity compared to traditional open sheds. The lateral walls are equipped with lateral wire mesh and manual or automated winch-operated fabric curtains. Axial exhaust fans are installed at one end of the shed to draw air through wet evaporative cooling pads located at the opposing end.

Environmental Controls

• Temperature: Operates in mechanical mode when ambient thermal stress exceeds 30°C to 35°C.
• Ventilation: Dual-mode strategy. Uses natural cross-ventilation during cool hours and negative-pressure mechanical ventilation during extreme heat.
• Air Speed: Target air velocity of 200 to 300 ft/min (~1.0 to 1.5 m/s).

Capacity & Layout

Standard configurations house 10,000 to 12,000 broilers or 5,000 to 6,000 layers.

Equipment Integration

Inlet Deflector Curtains, Evaporative Cooling Pads, Tube Feeders, Automatic Nipple Drinkers, Bell Drinkers.

Advantages

Bridges the gap between passive and mechanical environments at a moderate capital cost. Integrators incentivize these setups with adjusted growing charges (GC) policies (e.g., standard production incentives of up to INR 8.50 to 9.00 per kg) to offset the installation costs. Offers an improved target FCR of 1.58.

Limitations

Suffers from a severe lack of structural airtightness. High static pressure variability (0.01 to 0.05 inches of water column) results in air leakage through curtain seams, pulley points, and structural joints. Bypass air leads to uneven cooling, localized stagnant hot zones, and increased bird mortality near curtain leaks.

Biosecurity Features

Drafty leaks can draw dust and outside pathogens into the house, increasing respiratory risks.

Maintenance

Winch systems must be lubricated with silicone-based sprays. The building envelope must be inspected for air leaks quarterly, and any tears in curtains or wall joints must be sealed to maintain negative pressure control.

Quantitative Data

• Bird Capacity: 10,000 to 12,000 broilers or 5,000 to 6,000 layers.
• Stocking Density: 1.0 sq ft (~0.09 m²) per broiler; 1.5 to 2.0 sq ft per layer.
• Temperature Range: Switches to mechanical cooling at > 30°C to 35°C.
• Air Speed: 200 to 300 ft/min (~1.0 to 1.5 m/s).
• Dimensions: Standard width 10.0 m to 12.0 m.

Relationships

• Equipment: Inlet Deflector Curtains, Evaporative Cooling Pad.
• Environmental Parameters: Static Pressure Variability (0.01 to 0.05 in H₂O).
• Breeds: Cobb 430 Y.
• Diseases: Heat Stress.
• Production Systems: Contract Farming Integration Frameworks (IB Group, Kalyan Hatcheries).
• Calculators: Growing Charges (GC) rates.