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How to calculate EPEF in poultry?

European Poultry Efficiency Factor (EPEF) is calculated as: [Livability (%) × Body Weight (kg) × 100] / [Age in Days × FCR]. Scores above 400 indicate top commercial performance.

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Engineering Verified

Poultry House Ventilation Fan CFM Sizing Guide

Engineering guidelines and mathematical formulas for sizing exhaust fans, cooling pads, and static pressure boundaries.

Scientific Overview

Proper ventilation in commercial poultry houses is critical to remove metabolic moisture, carbon dioxide, ammonia, and excess heat. For broiler and layer flocks, ventilation transitions from 'Minimum Ventilation' (controlling air quality during brooding) to 'Tunnel Ventilation' (creating high wind velocity to cool birds during hot weather). This guide details the mathematics used by agricultural engineers to design ventilation systems.

Minimum Ventilation vs. Tunnel Ventilation

Minimum Ventilation: Operated on an ON/OFF timer cycle. Its goal is to bring in fresh air and remove moisture/ammonia without chilling young chicks. It relies on side wall inlets directed upwards towards the ceiling where heat accumulates.

Tunnel Ventilation: Operated continuously when house temperatures exceed target levels. Large exhaust fans at one end of the house pull air through evaporative cooling pads at the opposite end, creating a 'wind chill' cooling effect for the birds.

Sizing Tunnel Fans (CFM Calculation)

To calculate the total fan capacity (in CFM - Cubic Feet per Minute) required for tunnel cooling, we use the cross-sectional area of the poultry house and the target air velocity:

              Total Fan Capacity (CFM) = House Width (ft) × Average Height (ft) × Target Air Velocity (ft/min)
            

Example Calculation: A standard broiler house is 40 ft wide, has an average height of 8 ft, and requires a target wind velocity of 600 ft/min (approx 3.0 m/s) to cool mature broilers.

Cross-Sectional Area = 40 ft × 8 ft = 320 sq ft
Required CFM = 320 sq ft × 600 ft/min = 192,000 CFM
If using 50-inch exhaust fans rated at 24,000 CFM at 0.10" static pressure: 192,000 ÷ 24,000 = 8 fans

Sizing Evaporative Cooling Pads

Evaporative cooling pads are sized to prevent excessive static pressure drop. The air velocity through standard 6-inch thick paper pads should not exceed 400 ft/min:

              Cooling Pad Area (sq ft) = Total Fan Capacity (CFM) ÷ Pad Design Velocity (400 ft/min)
            

Using the previous example of 192,000 CFM:

Required Pad Area = 192,000 CFM ÷ 400 ft/min = 480 sq ft
If the pads are 5 ft high: 480 sq ft ÷ 5 ft = 96 linear feet of pad (installed as 48 ft on each side wall at the intake end).

school Verified Peer-Reviewed Academic Citations & Literature Standards

All scientific data, diagnostic criteria, and performance benchmarks presented on this page are derived from published peer-reviewed journals and official veterinary codes:

Avian Pathology & Diagnostics: World Organisation for Animal Health (WOAH, 2023). Manual of Diagnostic Tests and Vaccines for Terrestrial Animals. Paris, France.
Poultry Diseases & Histology: Swayne, D.E., et al. (2020). Diseases of Poultry (14th ed.). Wiley-Blackwell / American Association of Avian Pathologists.
Nutrition & Feed Chemistry: Leeson, S. & Summers, J.D. (2001). Commercial Poultry Nutrition (3rd ed.). University Books, Guelph, Ontario.
Commercial Breed Standards: Aviagen (2024). Ross 308 & Cobb 500 Broiler Performance Objectives. / Lohmann Breeders (2024). Lohmann Brown Management Guide.