Comprehensive Design Guide for Layer House Ventilation Systems
Scientific Calculation × Equipment Selection × Practical Case Studies
Download the Fully Automated Layer House Ventilation Calculator via the end link. This tool auto-computes critical parameters including seasonal airflow, equipment sizing, and pressure optimization. Results require field validation and professional assessment.
I. Core Ventilation Parameter Calculations
1. Ventilation Requirement (CFM)
- Basic Formula:
Total Airflow (m³/h) = House Volume × Air Changes per Hour- House Volume (m³) = Length × Width × Average Height
- Air Change Standards: SeasonChanges/HourTargetWinter5-8Maintain minimum ventilationSpring/Autumn10-15Balance temperature & humiditySummer60Emergency cooling (full air replacement in 1 min)
- Precision Calculation (Weight-Based):
Total Airflow = Body Weight (kg) × Bird Count × Ventilation Coefficient- Ventilation Coefficients:
- Chicks: 3.68 m³/h/kg
- Adults: 4.76 m³/h/kg (base) | Hot season: 7.6 m³/h/kg
- Ventilation Coefficients:
2. Fan Quantity Calculation
N = Total Airflow (m³/h) ÷ [Single Fan Capacity (m³/h) × Efficiency Factor (0.9)] Case Study: 100m×12.5m×4m house, summer demand
- Total Airflow = 35,000 birds × 2kg × 7.6 m³/h = 532,000 m³/h
- Using 50-inch fans (43,500 m³/h):
N = 532,000 ÷ (43,500 × 0.9) ≈ 13.5 → Install 14 fans
II. Key Ventilation Design Principles
1. Air Velocity Control
| Scenario | Velocity | Effect |
|---|---|---|
| Minimum Ventilation | ≥1 m/s | Prevent cold air stagnation |
| Cooling Ventilation | 1.5-2.5 m/s | Reduce perceived temperature by 3-5℃ |
| Tunnel Ventilation | 2.5-3 m/s | Emergency cooling (>28℃) |
2. Inlet Design
- Area Calculation:
Inlet Area (m²) = Total Airflow (m³/h) ÷ 3600 ÷ Inlet Velocity (m/s)- Inlet Velocity Standards:
- Cross Ventilation: ≤5 m/s
- Tunnel Ventilation: 3.5-4 m/s
- Inlet Velocity Standards:
- Layout Requirements:
- Inlet height ≥ 80% of eave height
- 150m inlet length per 10,000 birds (10cm width)
3. Cooling Pad Sizing(cooling system)
- Pad Area Formula:
Pad Area (m²) = Total Airflow (m³/h) ÷ [3600 × Pad Air Velocity (m/s)]- Pad Air Velocity:
- 15cm pad: 1.5-2 m/s (ideal)
- 10cm pad: 1-1.5 m/s
- Pad Air Velocity:
- Case Study: 14×50-inch fans (609,000 m³/h)
Pad Area = 609,000 ÷ (3600 × 2) ≈ 84.6 m²
III. Critical Environmental Metrics
1. Effective Temperature Control
| Age (days) | Temp (℃) | RH (%) | Air Velocity (m/s) |
|---|---|---|---|
| 1-7 | 33→31 | 50 | ≤0.2 |
| 8-21 | 29→25 | 60→65 | 0.5-1.0 |
| 22-35 | 21→20 | 70→75 | 1.5-2.0 |
| 36+ | 18 | 80 | 2.0-2.5 |
Effective Temp Formula:
Effective Temp = Dry Bulb Temp – 3×Air Velocity + 0.1×(RH-50)
2. Negative Pressure Control
- Optimal Range: 12-25 Pa (0.05-0.1 in H₂O)
- Measurement: 1m height at house center
IV. Equipment Selection & Maintenance
1. Fan Performance Specifications
| Model | Airflow (m³/h) | Power (kW) | Coverage Area (m²) |
|---|---|---|---|
| 36-inch | 16,980 | 0.37 | 800-1,000 |
| 48-inch | 33,960 | 1.1 | 1,500-1,800 |
| 50-inch | 42,500 | 1.5 | 1,800-2,200 |
2. Ventilation Mode Switching
| House Temp (℃) | Mode | Fans Used | Inlet Opening |
|---|---|---|---|
| <18 | Cross Ventilation | ≤30% | 10-20% |
| 18-25 | Transition | 30-70% | 30-50% |
| >25 | Tunnel Ventilation | 100% | Full Open |
V. Troubleshooting & Optimization
Common Issues:
- **>3℃ Temp Difference**:
→ Check inlet uniformity; add airflow guides - NH₃ >20ppm:
→ Verify minimum ventilation; inspect manure belts - Poor Pad Cooling:
→ Clean pad pores; ensure water flow ≥4L/min·m²
Efficiency Upgrades:
- Variable Frequency Drives: Reduce energy use by 30%
- Auto Pressure Control: Maintain 12 Pa dynamically
Appendix: Quick Reference Tools
| Parameter | Formula/Value | Application |
|---|---|---|
| House Cross-Section | Width × Avg. Height | Air velocity calculation |
| Ventilation Coefficient | 4.76 m³/h/kg (adults) | Precision airflow |
| Fan Efficiency | 0.9 (post-maintenance) | Fan quantity calculation |
| Pad Air Velocity | 1.5-2 m/s (15cm pad) | Pad sizing |
Case Verification: 100m×12.5m house, 35,000 layers
- Summer Airflow: 532,000 m³/h → 14×50-inch fans
- Pad Area: 84.6 m² → 8×10.5m² pads
- Result: 26℃ indoors at 32℃ outdoors (65% RH)
Immediate Actions:
- Download Ventilation Calculator Excel Template → [Click Here]
- Get Negative Pressure Tuning Guide → [Scan QR Code]
(Complies with GB/T 30435-2021 & ISO 15999 Standards)
About Broiler House Ventilation Systems you can see this:
Complete Guide to Ventilation and Cooling Pad System Design for Broiler Farms
Download the Fully Automated Layer House Ventilation Calculator
Self-calculating spreadsheet for precision airflow planning:
