Calculator
Ventilation
Tunnel wind speed = total fan CFM ÷ house cross-section. Typical breeder target is about 2.0–2.5 m/s (400–500 ft/min) — set your own standard.
1. House & fan capacity
What to measure
Use the fan's rated CFM at the working static pressure (e.g. 0.10" water column), not free-air CFM. Target 2.50 m/s = 492 ft/min.
Expected wind speed
3.15 m/s
619 ft/min
Fans needed for 2.5 m/s
7
Installed fans are enough
Total fan capacity
200,000 CFM
Required 158,916 CFM
Air exchange
0.53 min
Time to replace all house air (aim ≤ 1 min in tunnel)
Cross-section
323 ft²
30.0 m²
House volume
105,944 ft³
3,000 m³
2. Actual reading vs standard
Actual 1.80 m/s · 354 ft/min · Standard 2.50 m/s · 492 ft/min. Measure with an anemometer at bird level, in the middle of the house, averaging several points across the width.
Fans needed to reach standard
9
Turn on 3 more fans
Speed per fan
0.300 m/s
59.1 ft/min
Gap to standard
0.70 m/s
138 ft/min
Of standard
72%
Assumes each fan adds the same speed: 1.80 m/s ÷ 6 fans = 0.300 m/s per fan; 2.50 ÷ 0.300 = 8.33 → 9 fans. Low readings with all fans on point to dirty shutters, loose belts or air leaks.
3. Cooling pad area
Cooling pad area needed
39.7 m²
About 40 m² · 428 ft²
Total airflow
4,528 m³/min
159,905 CFM
Area per side
19.9 m²
2 sides
Pad length per side
9.9 m
at 2.0 m high
Pad area = (fan capacity × fans) ÷ air speed through pad: (566 × 8) ÷ 114 = 39.7 m².
Cobb standard wind speed by flock age
Recommended air speed at bird level (ventilation) based on age, for broilers and broiler breeders. Use this chart to set the target speed in section 1 and the standard speed in section 2 for the age of your flock.
