Tunnel ventilation for poultry houses in hot, humid climates
How tunnel ventilation and evaporative pads cool birds in hot-humid regions, why humidity limits pad cooling, and what to ask bidders before you buy fans and pads.
By HatchMatch Group Editorial Desk · Last updated 2026-10-13
In short
Short answer: tunnel ventilation cools poultry by moving air at speed along the length of the house, creating a wind-chill effect on the birds; evaporative pads at the inlet end lower the incoming air temperature. In humid climates the pads cool less because the air is already close to saturation, so air speed, fan performance at real static pressure and airtight houses matter more. Ask every bidder to state the design air speed, airflow and static pressure behind their design.
Key takeaways
- Tunnel ventilation brings air in through large openings at one end of the house — usually through evaporative cooling pads — and exhausts it with fans at the opposite end.
- Evaporative cooling depends on how dry the incoming air is.
- Fan airflow at the static pressure the house will actually run at, not only at zero pressure, from independent test data where available.
- Heat stress reduces feed intake and growth in broilers and egg output in layers, and can raise mortality during heat waves.
- Use the ventilation calculator for a planning airflow estimate and the poultry house energy calculator for running cost.
Short answer: tunnel ventilation cools poultry by moving air at speed along the length of the house, creating a wind-chill effect on the birds; evaporative pads at the inlet end lower the incoming air temperature. In humid climates the pads cool less because the air is already close to saturation, so air speed, fan performance at real static pressure and airtight houses matter more. Ask every bidder to state the design air speed, airflow and static pressure behind their design.
What is tunnel ventilation?
Tunnel ventilation brings air in through large openings at one end of the house — usually through evaporative cooling pads — and exhausts it with fans at the opposite end. The air moving past the birds removes heat. It is used in hot weather; in cool weather the house switches to minimum ventilation through side or ceiling inlets to control moisture and air quality without chilling the birds.
Why does tunnel ventilation underperform in humid climates?
Want these figures for your own site, capacity and country? A HatchMatch specialist builds the budget with you — no buyer fees.
Start freeEvaporative cooling depends on how dry the incoming air is. When relative humidity is high, less water evaporates and the temperature drop through the pads shrinks, while the extra moisture can raise heat stress. That puts more weight on air speed. Common causes of poor performance are fans that lose airflow once pads are wet and static pressure rises, air leaks that let air bypass the pads, undersized pad area that raises pressure, and dirty or scaled pads and shutters.
What should buyers ask fan and pad suppliers?
- Fan airflow at the static pressure the house will actually run at, not only at zero pressure, from independent test data where available.
- The design air speed in the bird zone and how many fans run at each stage.
- Pad area, thickness and the assumed air velocity through the pad.
- How the controller stages fans, pads and inlets, and which sensors it uses.
- Power demand at full tunnel and whether the standby generator can carry it.
- Water quality requirements for pads and the cleaning and replacement schedule.
How does this connect to welfare and production results?
Heat stress reduces feed intake and growth in broilers and egg output in layers, and can raise mortality during heat waves. A ventilation design is therefore a production decision, not only a building one. Agree measurable acceptance tests at commissioning, such as air speed readings along the house and static pressure at full tunnel.
Next steps
Use the ventilation calculator for a planning airflow estimate and the poultry house energy calculator for running cost. For the wider climate package, see poultry house climate control. For commercial projects from USD 250,000, submit a project brief; our team structures one comparable RFQ and approaches suitable suppliers on your behalf.
Frequently asked questions
- What is tunnel ventilation?
- Tunnel ventilation brings air in through large openings at one end of the house — usually through evaporative cooling pads — and exhausts it with fans at the opposite end. The air moving past the birds removes heat. It is used in hot weather; in cool weather the house switches to minimum ventilation through side or ceiling inlets to control moisture and air quality without chilling the birds.
- Why does tunnel ventilation underperform in humid climates?
- Evaporative cooling depends on how dry the incoming air is. When relative humidity is high, less water evaporates and the temperature drop through the pads shrinks, while the extra moisture can raise heat stress. That puts more weight on air speed. Common causes of poor performance are fans that lose airflow once pads are wet and static pressure rises, air leaks that let air bypass the pads, undersized pad area that raises pressure, and dirty or scaled pads and shutters.
- What should buyers ask fan and pad suppliers?
- - Fan airflow at the static pressure the house will actually run at, not only at zero pressure, from independent test data where available. - The design air speed in the bird zone and how many fans run at each stage. - Pad area, thickness and the assumed air velocity through the pad. - How the controller stages fans, pads and inlets, and which sensors it uses. - Power demand at full tunnel and whether the standby generator can carry it. - Water quality requirements for pads and the cleaning and replacement schedule.
- How does this connect to welfare and production results?
- Heat stress reduces feed intake and growth in broilers and egg output in layers, and can raise mortality during heat waves. A ventilation design is therefore a production decision, not only a building one. Agree measurable acceptance tests at commissioning, such as air speed readings along the house and static pressure at full tunnel.
More buyer questions are answered in our poultry procurement FAQ — also available in Español, Français, Português, Deutsch, العربية, Русский, Türkçe, Tiếng Việt.
From this article to a procurement-ready RFQ
HatchMatch Group is an independent sourcing desk — not a manufacturer or EPC contractor. These are the four steps we actually use with commercial poultry and hatchery buyers. If you are still deciding scope, start with what commercial poultry equipment includes and how suppliers are compared.
- 1. Plan the projectCapacity, climate and house layout in one guided workflowOpen
- 2. Build the RFQScope, specifications and comparable line itemsOpen
- 3. Submit the requestReviewed manually before HatchMatch contacts any supplier on the buyer's behalfOpen
- 4. Track and compareFollow status and normalise supplier responsesOpen
Prefer the numbers first? Start with the poultry project cost calculator or browse the project planning guides.
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