Ventilation & Cooling Systems

Why Ventilation and Cooling Matter

Heat stress is one of the biggest threats to dairy production and profitability. When Temperature-Humidity Index (THI) exceeds 68, cows begin experiencing heat stress that reduces feed intake, milk production, and reproduction. Effective ventilation and cooling systems can mitigate these effects and maintain production through summer months.

Types of Ventilation Systems

Natural Ventilation

Relies on building design, wind, and temperature differences to move air. Works well in mild climates but may be insufficient during extreme heat or calm conditions. Lower cost but less controllable.

Tunnel Ventilation

Large fans at one end of the barn pull air through at high velocity. Creates significant air movement over cows but requires sealed buildings and may have temperature gradients.

Cross Ventilation

Fans pull air across the barn width. Common in newer freestall barns; provides uniform air movement throughout the building.

Hybrid/Combination Systems

Natural ventilation supplemented with fans when conditions require additional air movement. Balances energy costs with cooling effectiveness.

Cooling Technologies

High-Volume Low-Speed (HVLS) Fans

Large ceiling fans (18-24 ft diameter) move massive air volumes at low speed. Energy-efficient but provide relatively low air velocity directly over cows.

Panel/Box Fans

Traditional high-speed fans mounted over stalls or in feedline areas. Provide targeted high-velocity air movement where cows spend the most time.

Sprinkler/Soaker Systems

Wet the cows' hide so evaporation provides cooling. Most effective when combined with fans for evaporation. Requires proper drainage and water management.

Evaporative Cooling Pads

Water-saturated pads cool incoming air through evaporation. Works best in dry climates; less effective in humid conditions.

Shade Structures

Block direct solar radiation, which can add significant heat load. Important for outside areas like holding pens and dry lots.

Key Design Considerations

Air Velocity Goals

Target 5-8 mph air velocity over resting cows during heat stress. Higher velocities provide more cooling but require more energy.

Critical Areas

Prioritize cooling in holding pens (where cows crowd before milking) and freestall resting areas where cows spend the most time.

Water Availability

Sprinkler systems increase water consumption significantly. Ensure adequate supply and consider drainage/manure handling implications.

Energy Costs

Cooling systems can add substantial electricity costs during summer. Evaluate energy-efficient options and consider demand charges.

Do You Need Cooling Upgrades?

Consider improvements if:

• Milk production drops significantly in summer
• Cows show visible heat stress signs (panting, reduced lying time)
• Conception rates decline during hot months
• Current ventilation was designed for a smaller herd
• Building modifications have changed airflow patterns

Cost Considerations

Panel fans cost $500-1,500 each plus installation. HVLS fans range from $8,000-15,000 per fan. Complete sprinkler systems may cost $50-100 per cow. Tunnel or cross-ventilation retrofits can exceed $100,000 for larger barns. Weigh costs against summer production losses to determine ROI.