# Cooling Systems for Poultry Houses: Combating Heat Stress ## Key Takeaways - Heat stress in poultry commences when the Temperature-Humidity Index (THI) exceeds 80, necessitating proactive intervention before visible signs like panting manifest. Birds rely on panting and wing spreading to dissipate heat, but these mechanisms become insufficient when ambient temperatures approach their normal body temperature of 105-107°F, especially in high humidity. - Evaporative cooling, primarily through cooling pads or fogging systems, is highly effective in reducing air temperature by 10-20°F, but its efficacy is significantly diminished when relative humidity surpasses 80%. Tunnel ventilation, achieving air speeds of 400-600 feet per minute, forms the foundational airflow strategy, crucial for dissipating body heat even at temperatures above 90°F. - Water management is critical, with birds increasing intake substantially during heat events; ensuring adequate flow rates (2-4 oz/min per nipple for mature birds) and cool water temperatures (below 90°F) is paramount. Electrolyte supplementation can aid in maintaining fluid balance by replacing minerals lost through panting. - Passive cooling strategies such as roof insulation (R-19 or higher), reflective roof coatings, and shade structures reduce solar heat gain, while night purging utilizes cooler nighttime air to flush accumulated heat from the house structure. - Monitoring bird behavior (panting, wing spreading, reduced activity) is a more sensitive indicator of heat stress than temperature alone, and an emergency plan addressing airflow, water, and vulnerable bird prioritization should be in place before heat waves. - Common errors include relying solely on temperature, operating evaporative cooling in high humidity, neglecting fan maintenance (which can reduce airflow by 30-50%), and failing to clean cooling pads, all of which compromise effective heat stress mitigation. --- Heat stress is one of the most costly and dangerous challenges facing poultry producers, regardless of whether you raise broilers, layers, or breeding stock. When birds cannot dissipate heat effectively, their feed intake drops, egg production falls, growth rates slow, and in severe cases, mortality can spike within hours. This guide explains how heat stress develops in poultry, how to evaluate your current ventilation and cooling setup, and how to install, operate, and maintain the cooling systems that keep your flock healthy during hot weather. It is written for commercial farmers, small flock owners, and farm employees who want practical, actionable guidance on cooling chicken coops and poultry houses effectively. ## At a Glance - **Heat stress begins before you see panting.** Birds start experiencing heat stress when the temperature-humidity index (THI) rises above 80. Take action before birds show visible distress. - **Evaporative cooling is the most effective tool** for most poultry houses, but it only works when relative humidity is below about 80 percent. - **Tunnel ventilation is the foundation.** No cooling system can overcome poor airflow. Install or verify tunnel ventilation before adding pads or foggers. - **Air speed matters more than temperature alone.** Moving air at 400 to 600 feet per minute across the birds removes body heat effectively even when air temperature is above 90 degrees Fahrenheit. - **Cooling pads lower temperature by 10 to 20 degrees Fahrenheit** when sized and maintained correctly. Dirty or clogged pads reduce performance dramatically. - **Fogging and misting systems work best in dry climates.** They add moisture to the air, so they are counterproductive in humid regions. - **Water is the first line of defense.** Cool, clean drinking water helps birds regulate body temperature. Check flow rates and water temperature daily during heat events. - **Monitor birds, not just thermometers.** Panting, wing spreading, and reduced activity are earlier signs of heat stress than mortality. - **Have an emergency plan before the heat wave arrives.** Know which birds to move, how to increase airflow, and when to call for help. ## Understanding Heat Stress in Poultry Birds do not sweat. Unlike mammals, poultry have no sweat glands, so they rely on other methods to shed excess body heat. They pant, which evaporates moisture from the respiratory tract, and they hold their wings away from their bodies to expose cooler skin surfaces. They also reduce feed intake because digesting feed generates body heat, and they drink more water to replace what they lose through panting. These coping mechanisms work well in mild heat but fail quickly as temperatures climb. A chicken's normal body temperature is around 105 to 107 degrees Fahrenheit. When ambient temperature approaches that range, the bird cannot lose heat to the environment through radiation or convection. It must rely almost entirely on evaporative cooling from panting. If the air is humid, evaporation slows, and the bird's internal temperature rises even faster. Heat stress in poultry is not a single event. It exists on a continuum from mild discomfort to acute heat stroke. The temperature-humidity index (THI) gives you a practical way to assess risk. You calculate THI using dry bulb temperature and relative humidity. When THI is below 80, birds are generally comfortable. When THI reaches 80 to 85, birds begin to show signs of stress. Above 85, feed intake drops sharply, and mortality risk increases. Above 90, death losses can occur rapidly if you do not intervene. Several factors make heat stress worse. High stocking density means more birds generating body heat in the same space. Poor insulation allows radiant heat from the roof to penetrate the house. Dark feather colors absorb more solar radiation than light colors. Large birds have a harder time shedding heat than small birds because their surface area to volume ratio is lower. Broilers in the final weeks of growout are especially vulnerable. Heavy laying hens also struggle because egg production generates additional metabolic heat. The economic impact of heat stress extends beyond mortality. Even when birds survive, they perform poorly. Broilers gain less weight and convert feed less efficiently. Layers produce smaller eggs and lay fewer of them. Fertility drops in breeding flocks. Immune function weakens, making birds more susceptible to disease. These losses often exceed the cost of installing and operating a proper cooling system. ## Evaluating Your Current Ventilation System Before you purchase any cooling equipment, you need to understand how air moves through your poultry house. Cooling systems only work when they have a steady supply of fresh air moving across the birds. If your ventilation system is undersized, poorly maintained, or improperly configured, no amount of cooling equipment will solve the problem. Start by measuring your house dimensions and calculating the total floor area. For tunnel ventilation, you need enough exhaust fan capacity to move air at the recommended velocity. Most poultry houses aim for 400 to 600 feet per minute (fpm) of air movement during hot weather. To calculate the fan capacity needed, multiply the cross-sectional area of the house by the desired air speed. For example, a house that is 40 feet wide with an average ceiling height of 8 feet has a cross-sectional area of 320 square feet. To achieve 500 fpm, you need fans that can move 160,000 cubic feet per minute (cfm) total. Check the condition of your fans. Dirty fan blades, worn belts, and loose shutters reduce airflow significantly. A fan that is running but moving little air is worse than no fan at all because it gives you a false sense of security. Clean fan blades and shutters before each hot season. Replace worn belts and check that all fans are turning in the correct direction. Measure actual airflow with an anemometer rather than relying on fan ratings. Inspect your air inlets. In tunnel mode, the house should have large openings at one end to let air in and fans at the opposite end to pull air out. The inlet area should be roughly equal to the fan capacity, typically about 1 square foot of inlet area for every 600 to 800 cfm of fan capacity. If inlets are blocked by debris, nests, or equipment, airflow will suffer. Consider the condition of your house structure. Cracks and gaps in the walls and ceiling allow air to enter where you do not want it, which disrupts the tunnel airflow pattern. Seal leaks around doors, vents, and utility penetrations. Check that the ceiling is smooth and free of obstructions that would disrupt airflow. Trusses, hanging feeders, and other equipment can create turbulence that reduces effective air speed at bird level. ## Tunnel Ventilation as the Foundation Tunnel ventilation is the backbone of any poultry house cooling strategy. It works by pulling air lengthwise through the house at high velocity, creating a wind chill effect that helps birds shed heat. Even when air temperature is above 90 degrees Fahrenheit, moving air at 500 fpm can make birds feel as if the temperature is 10 to 15 degrees cooler. To set up tunnel ventilation, you need exhaust fans mounted at one end of the house and large inlet openings at the opposite end. The fans pull air through the house, and the inlet area must be sized to match fan capacity. If the inlets are too small, the fans create negative pressure that reduces airflow. If the inlets are too large, air velocity drops because the fans cannot move enough air to fill the space. Run tunnel fans whenever the temperature inside the house reaches about 75 to 80 degrees Fahrenheit, depending on bird age and size. For young chicks, start tunnel ventilation at a lower temperature because they cannot regulate their body temperature well. For mature birds, you can wait until the temperature approaches 80 degrees. The goal is to keep the temperature rise through the house below 5 degrees Fahrenheit from inlet to exhaust end. Monitor the temperature gradient across the house. In a properly ventilated tunnel house, the temperature at the exhaust end should be no more than 5 degrees warmer than at the inlet end. If the gradient is larger, you need more airflow, more inlet area, or both. A temperature gradient of 10 degrees or more indicates serious ventilation problems that cooling systems cannot overcome. During extreme heat, run all tunnel fans even if the temperature seems manageable. The air movement itself provides cooling benefit. You can also consider running some fans even when the house is empty before placing a new flock, to cool the building structure and reduce heat buildup in the walls and litter. ## Evaporative Cooling Systems Evaporative cooling is the most effective method for lowering air temperature inside a poultry house. These systems work by passing air through wet pads or by spraying fine water droplets into the air. As water evaporates, it absorbs heat from the air, lowering the temperature. The cooling effect depends on the difference between the dry bulb and wet bulb temperatures, which is a measure of how much moisture the air can absorb. ### Cooling Pads Cooling pads, also called evaporative pads or cellulose pads, are installed at the air inlet end of a tunnel ventilated house. Water is distributed over the top of the pads and flows down through the material. Incoming air passes through the wet pads, and evaporation cools the air before it enters the bird zone. Proper pad sizing is critical. The pad area must match the total fan capacity of the house. A general rule is to provide about 1 square foot of pad area for every 250 to 350 cfm of fan capacity. If the pads are too small, air velocity through the pads becomes too high, which reduces cooling efficiency and increases static pressure. If the pads are too large, you waste water and may not achieve the desired temperature drop. Install pads on the outside of the inlet openings, not inside the house. This keeps the pad frame and water distribution system accessible for maintenance. The pad housing should include a gutter system to collect and recirculate water. A sump tank stores water and houses the pump. The pump should be sized to deliver about 0.5 to 1.0 gallons per minute per linear foot of pad. The water distribution system must deliver water evenly across the entire top of each pad. Clogged distribution holes create dry spots that reduce cooling performance. Inspect the distribution pipes regularly and clean or replace clogged nozzles. Cooling pads can lower incoming air temperature by 10 to 20 degrees Fahrenheit when conditions are favorable. The actual temperature drop depends on relative humidity. In dry conditions with humidity below 50 percent, you can achieve the maximum cooling effect. When humidity rises above 70 percent, the cooling benefit diminishes significantly. Above 80 percent relative humidity, evaporative cooling provides little benefit and can actually make conditions worse by adding moisture to the air. ### Fogging and Misting Systems Fogging systems use high-pressure pumps to force water through fine nozzles, creating a mist of tiny droplets that evaporate quickly in the air. Misting systems use lower pressure and produce slightly larger droplets. Both systems cool the air by evaporation, similar to cooling pads, but they do not require the large pad installation. Fogging nozzles are typically installed along the length of the house, often near the ceiling or along the side walls. The system operates in short bursts controlled by a timer or thermostat. When the fog is on, water droplets evaporate and cool the surrounding air. The system should run only when relative humidity is low enough for evaporation to occur. The main advantage of fogging is flexibility. You can install it in houses that do not have a tunnel ventilation setup, and you can run it in short cycles to provide intermittent cooling. The main disadvantage is that it adds moisture to the litter and can increase humidity inside the house. In humid climates, fogging can make conditions worse by raising the dew point and reducing the birds' ability to cool themselves through panting. If you use a fogging system, run it in short bursts of 10 to 30 seconds with longer intervals between bursts. This allows the water to evaporate before the next burst begins. Running the system continuously saturates the air and leaves water dripping on the birds and litter. Monitor relative humidity closely and shut the system off when humidity exceeds 75 to 80 percent. ### Sprinkler and Spray Systems Sprinkler systems deliver larger water droplets directly onto the birds. This is a different approach from evaporative cooling. The water wets the birds' skin and feathers, and the water evaporates directly off the bird, removing body heat. This is similar to how sweating works in mammals. Sprinklers are most useful for mature birds in houses where evaporative cooling is not practical. They are common in hot, dry climates and in houses with open or semi-open designs. The system should wet the birds thoroughly but not saturate the litter. Run sprinklers for short periods, typically 1 to 3 minutes, followed by a longer dry period to allow the water to evaporate off the birds. The main risk with sprinklers is that wet litter promotes ammonia production and foot pad lesions. Use sprinklers only when temperatures are extreme and other cooling methods are insufficient. Monitor litter moisture closely and adjust the frequency of sprinkling based on how quickly the litter dries. ## Passive Cooling Strategies Not all cooling requires mechanical equipment. Several passive strategies can reduce heat load and make your cooling systems more effective. ### Roof Insulation and Reflectivity The roof is the largest surface exposed to solar radiation. A dark metal roof absorbs heat and transfers it into the house. Light colored or reflective roof coatings can reduce heat gain significantly. White or silver reflective coatings can lower roof surface temperature by 20 to 40 degrees Fahrenheit compared to dark surfaces. Insulation under the roof reduces heat transfer into the house. The recommended R-value for poultry house roofs varies by climate, but R-19 or higher is common in hot regions. Proper insulation keeps the house cooler during the day and helps retain heat during cold weather, so it pays for itself year round. ### Ridge Vents and Cupolas Ridge vents run along the peak of the roof and allow hot air to escape naturally. As hot air rises, it exits through the ridge vent, drawing cooler air in through lower openings. This natural convection works best when there is little wind and the house is not running tunnel ventilation. Cupolas serve a similar function on houses with a peak. They provide an opening at the highest point of the roof where hot air can escape. Some cupolas include fans to actively exhaust hot air. These are most useful in houses that do not have a full tunnel ventilation system. ### Shade and Landscaping Trees and shade structures on the south and west sides of the house reduce solar heat gain. Deciduous trees provide shade in summer and allow sunlight through in winter after they lose their leaves. However, trees should not be so close that they block ventilation openings or interfere with fan airflow. Shade cloth over the roof or above outdoor runs can reduce radiant heat load significantly. Use shade cloth with 50 to 80 percent shade factor, depending on your climate and the house design. The cloth should be mounted several inches above the roof surface to allow air movement between the cloth and the roof. ### Night Purging In many climates, nighttime temperatures drop below daytime highs. You can use this cooler air to remove heat stored in the house structure. Run ventilation fans at night to pull cool air through the house and flush out accumulated heat. This reduces the starting temperature for the next day and helps birds recover from daytime heat stress. Night purging is most effective when the nighttime temperature drops at least 15 to 20 degrees below the daytime high. In regions where nights stay hot, this strategy provides less benefit. Run tunnel fans at low to medium speed during the night, or run circulation fans to mix the air. ## Water Management for Heat Relief Water is the most critical nutrient during heat stress. Birds increase their water intake dramatically when temperatures rise. A laying hen that drinks about 0.5 gallons per day in moderate weather may drink twice that during a heat wave. Broilers show similar increases. Ensure that water flow rates are adequate for your flock size and bird age. Nipple drinker systems should provide a minimum flow rate of about 2 to 4 ounces per minute per nipple for mature birds. Check flow rates at the end of each line, not just at the beginning. Water pressure drops along the length of the line, so the last nipples may deliver less water than the first. Water temperature matters. Birds prefer cool water, and cool water helps lower body temperature. In hot weather, water in uninsulated pipes can reach 90 degrees Fahrenheit or higher. Insulate water lines where they run through hot areas, especially near the ceiling. Flush water lines regularly to remove water that has been sitting in the sun. Some producers run a continuous small flow through the lines during extreme heat to keep water fresh and cool. Add electrolytes to drinking water during heat stress events. Electrolyte supplements replace minerals lost through panting and help birds maintain fluid balance. Follow the manufacturer's dosage recommendations. Do not leave electrolyte solutions in the lines longer than the recommended time, as they can promote bacterial growth. Check drinker height and adjust it so birds can drink easily without stretching. During heat stress, birds may be reluctant to move, so water must be easily accessible. Provide extra water drinkers or supplementary water sources during extreme heat events, especially for young birds or birds at high stocking density. ## Managing Bird Density and Feeding Schedules Stocking density directly affects heat load. More birds in a house means more body heat generated and more competition for cooling. During hot weather, reduce stocking density if possible. This may mean marketing broilers at a lighter weight, moving birds to another house, or delaying placement of a new flock until temperatures moderate. For broilers in the final week of growout, consider early marketing. The last few days of growth produce the largest birds, which are the most vulnerable to heat stress. Marketing a day or two early can reduce mortality risk significantly. Calculate the potential weight gain against the risk of heat losses before making this decision. Feeding schedules influence heat production. Digestion generates metabolic heat, so feeding during the hottest part of the day adds to the birds' heat load. Shift feeding to the cooler morning and evening hours. For broilers, use a feed program that provides the majority of the daily ration during cooler periods. For layers, consider feeding a larger portion of the daily ration in the evening so that egg formation occurs during cooler hours. Feed form also matters. Pelleted feed generates less heat during digestion than mash because birds eat pellets faster and spend less energy eating. However, the heat of digestion is similar regardless of feed form. The main benefit is that birds consume their ration more quickly, reducing activity during hot periods. Avoid feed outages during heat waves. Birds that have been without feed may overeat when feed is restored, which can cause digestive upset and increased heat production. Keep feed lines full and check feed delivery schedules to ensure you have adequate supply. ## Monitoring and Recordkeeping You cannot manage what you do not measure. A proper monitoring system tells you when conditions are becoming dangerous and helps you evaluate whether your cooling systems are working. Install temperature sensors at multiple locations in the house. At minimum, place sensors at the inlet end, the middle, and the exhaust end. Sensors should be at bird level, not at ceiling height. Ceiling temperatures can be 10 to 20 degrees warmer than bird level, so ceiling sensors give a false sense of security. Relative humidity sensors are equally important. You need to know humidity to calculate THI and to decide whether evaporative cooling will be effective. Place humidity sensors away from cooling pads and foggers so they measure the house environment, not the local effect of the cooling equipment. Keep records of temperature, humidity, and THI at regular intervals during heat events. Record which cooling equipment was running, what fan settings were used, and any changes you made. Also record bird behavior, feed intake, water intake, and mortality. These records help you identify patterns and improve your response over time. A simple recordkeeping system can be as basic as a notebook or spreadsheet. More sophisticated systems use data loggers that record conditions automatically and send alerts when thresholds are exceeded. Regardless of the system you use, the key is consistency. Record data at the same times each day so you can compare conditions day to day. Review your records after each heat event. Ask yourself what worked, what did not, and what you would do differently next time. This review process is how you refine your heat stress management plan. ## Emergency Response Plan Every poultry house needs an emergency plan for extreme heat events. When temperatures spike and cooling systems fail, you may have only minutes to act. A written plan ensures everyone on the farm knows what to do. Start by identifying the conditions that trigger emergency response. This could be a THI above 90, a temperature above 100 degrees Fahrenheit, or visible signs of heat stress in a significant percentage of birds. Define these triggers clearly so there is no confusion about when to act. Your emergency plan should include steps to increase airflow immediately. This means running all available fans, opening all inlets, and possibly using portable fans to supplement the fixed system. If you have access to a generator, verify it is in working condition and has fuel. Power outages during heat waves are especially dangerous, so a backup power source is essential. The plan should also include water emergency measures. Flush water lines to provide cool water. Add ice to water tanks if necessary. Provide supplemental water sources such as extra drinkers or pans if the main system fails. Know which birds are most vulnerable and prioritize them. Young chicks, heavy broilers, and birds near peak egg production are at highest risk. If you need to move birds to a cooler location, move the most vulnerable ones first. Designate a person to monitor the flock continuously during a heat event. This person should check birds every 15 to 30 minutes and report any changes immediately. Heat stress can progress from mild distress to death in under an hour, so vigilance is critical. ## Common Mistakes in Poultry House Cooling Several recurring mistakes undermine cooling efforts. Being aware of these can help you avoid them. **Relying on temperature alone.** Many producers check only temperature and ignore humidity. A temperature of 95 degrees with 30 percent humidity is much less dangerous than 90 degrees with 80 percent humidity. Always consider THI, not just temperature. **Running evaporative cooling in high humidity.** Cooling pads and foggers add moisture to the air. When relative humidity is above 80 percent, these systems provide little cooling and can worsen conditions. Shut them off and rely on airflow alone. **Ignoring the temperature gradient.** A house that is comfortable at the inlet end but dangerously hot at the exhaust end has an airflow problem. Check the gradient regularly and increase airflow or adjust inlets if the gradient exceeds 5 degrees. **Neglecting fan maintenance.** Dirty fans can lose 30 to 50 percent of their airflow. Clean fans before each hot season and check them periodically during the summer. Replace worn belts and lubricate bearings according to the manufacturer's recommendations. **Incorrect pad maintenance.** Cooling pads must be clean and properly wetted to work. Over time, pads accumulate dust, minerals, and algae. Clean pads according to the manufacturer's instructions and replace them when they become worn or clogged. Check that water distribution is even across the entire pad surface. **Forgetting about the birds.** Equipment can fail, and conditions can change faster than sensors detect. Look at the birds. Panting, wing spreading, reduced activity, and crowding near drinkers are early signs of heat stress. If birds are panting heavily, take action even if your sensors say conditions are acceptable. **Waiting too long to act.** Heat stress is easier to prevent than to reverse. Once birds are severely stressed, recovery is difficult. Take action at the first signs of heat stress, not after birds start dying. ## When to Call a Veterinarian or Extension Agent Most heat stress can be managed with proper cooling systems and good husbandry. However, there are times when you need professional help. Call a veterinarian if you see signs of disease along with heat stress. Respiratory distress, nasal discharge, swelling of the face or wattles, and sudden drops in feed or water intake can indicate infectious disease. Heat stress weakens the immune system, making birds more susceptible to infections. A veterinarian can help you distinguish between heat stress and disease and recommend appropriate treatment. Call a veterinarian or extension agent if you experience unexpected mortality patterns. If birds are dying despite your cooling systems running properly, or if mortality is concentrated in one area of the house, you may have an equipment failure or a disease problem that requires investigation. Call an extension agent if you are designing a new poultry house or retrofitting an existing one. Extension agents can provide guidance on fan capacity, pad sizing, and system design based on local climate conditions. They can also help you evaluate the cost effectiveness of different cooling options. Call a veterinarian immediately if you suspect a reportable disease. [Avian influenza](/knowledge/bacteria/avian-bacteria/avian-influenza-cdc-global-surveillance) and other reportable diseases can cause sudden death losses that mimic heat stress. If you see signs of respiratory disease, neurological signs, or a sudden spike in mortality, contact your veterinarian or state animal health officials right away. Do not wait to see if the problem resolves on its own. ## Cost Considerations and System Selection The right cooling system for your operation depends on your climate, house design, bird type, and budget. There is no single best system for every farm. Tunnel ventilation is the most cost effective investment you can make. It provides the foundation for all other cooling methods and is relatively inexpensive to install compared to evaporative systems. The main costs are fans, inlets, and the electricity to run them. For most producers, tunnel ventilation pays for itself through improved performance in the first year or two. Cooling pads are the next step for operations in hot, dry climates. The installation cost is moderate, and operating costs include water, electricity, and periodic pad replacement. Pads typically last 3 to 5 years with proper maintenance. The performance benefit is significant, with temperature drops of 10 to 20 degrees possible in dry conditions. Fogging systems are less expensive than cooling pads and can be added to existing houses more easily. They work well in dry climates but are not suitable for humid regions. Operating costs include electricity for the high pressure pump and water. Nozzles require regular cleaning and replacement. Sprinkler systems are the simplest and least expensive option. They use standard water pressure and inexpensive nozzles. They are most effective for mature birds in hot, dry climates. The main drawback is the potential for wet litter and the associated foot pad and ammonia problems. When comparing systems, consider both first cost and operating cost. A cheap system that does not perform well is more expensive in the long run than a more expensive system that works reliably. Also consider the value of the birds you are protecting. The cost of a cooling system is small compared to the value of a full house of broilers or layers. ## Seasonal Preparation Checklist Prepare your cooling systems before hot weather arrives, not during the first heat wave. A preseason checklist helps you identify problems while there is still time to fix them. Inspect and clean all fans. Remove dust from blades, shutters, and housings. Check belts for wear and replace if cracked or glazed. Lubricate bearings and check that motors are operating properly. Verify that all fans are turning in the correct direction. Clean cooling pads and check their condition. Remove any debris, mineral deposits, or algae. Replace pads that are worn, torn, or clogged. Check the water distribution system and clean nozzles and distribution pipes. Verify that the pump is operating correctly and that the sump tank is clean. Inspect water lines and drinkers. Flush lines to remove sediment and biofilm. Check water flow rates at the end of each line. Adjust drinker height for the current bird size. Insulate water lines that run through hot areas. Check the house structure. Seal any cracks or gaps in the walls and ceiling. Verify that inlets are operating correctly and can open fully. Clean inlet shutters and check that they seal tightly when closed. Test backup systems. Run your generator and verify it can power all critical equipment. Check fuel levels and have extra fuel on hand. Test alarm systems to ensure they function and that someone will hear them. Review your emergency plan with all farm employees. Make sure everyone knows the triggers for emergency response, the steps to follow, and who is responsible for each task. Practice the plan so that everyone knows what to do without having to think about it. ## Frequently Asked Questions **At what temperature do chickens start experiencing heat stress?** Chickens begin to show signs of heat stress when the temperature humidity index reaches about 80. This can occur at temperatures as low as 75 degrees Fahrenheit if humidity is very high, or at temperatures above 90 degrees if the air is very dry. The birds' age, size, and acclimation also matter. Young chicks and large mature birds are more sensitive than growing birds. Watch the birds rather than relying on temperature alone, and take action at the first signs of panting or wing spreading. **Is it better to use cooling pads or foggers in my poultry house?** The choice depends on your climate and house design. Cooling pads are more effective in hot, dry climates because they can lower incoming air temperature by 10 to 20 degrees Fahrenheit. They work best in tunnel ventilated houses where all incoming air passes through the pads. Foggers are less expensive and easier to retrofit but are less effective and can raise humidity. In humid climates, neither system works well, and you should focus on maximizing airflow instead. **How much airflow do I need in a tunnel ventilated poultry house?** Most poultry houses aim for 400 to 600 feet per minute of air velocity at bird level during hot weather. To calculate the fan capacity needed, multiply the cross sectional area of the house by the desired air speed. For example, a house that is 40 feet wide with an average height of 8 feet has a cross sectional area of 320 square feet. To achieve 500 fpm, you need fans that can move 160,000 cfm. Check actual airflow with an anemometer rather than relying on fan ratings. **Can I cool my poultry house with just ventilation, without evaporative cooling?** Yes, in many cases ventilation alone is sufficient. Moving air at 400 to 600 fpm creates a wind chill effect that helps birds shed heat even when air temperature is above 90 degrees Fahrenheit. In dry climates, ventilation alone can keep birds comfortable at temperatures up to about 95 degrees. Above that, evaporative cooling provides additional benefit. In humid climates where evaporative cooling is not effective, maximizing airflow is the best strategy. **How often should I clean my cooling pads?** Cooling pads should be inspected weekly during the cooling season and cleaned whenever they show signs of dust buildup, mineral deposits, or algae growth. Most manufacturers recommend a thorough cleaning at the start and end of each season. Between cleanings, check that water is distributed evenly across the entire pad surface and that there are no dry spots. Pads typically last 3 to 5 years with proper care, but heavy use or poor water quality can shorten their life. **What should I do when the power goes out during a heat wave?** Power outages during heat waves are extremely dangerous because birds lose both ventilation and cooling. Have a backup generator that can power all critical fans and pumps. Test the generator monthly and keep fuel on hand. If the power goes out, start the generator immediately and verify that all fans are running. If you do not have a generator, open all doors and windows to maximize natural airflow, and consider moving birds to shaded areas or using portable fans powered by a vehicle or battery system. **How can I tell if my birds are heat stressed before they start dying?** Watch for panting, which is rapid open mouthed breathing. Birds may hold their wings away from their bodies to expose more skin. They reduce feed intake and increase water intake. They become less active and may crowd near drinkers or in areas with better airflow. As stress increases, birds may show pale combs and wattles, and they may stagger or collapse. Monitor these signs regularly during hot weather and take action at the first signs of distress. **Should I reduce feed during hot weather?** Yes, reducing feed during the hottest part of the day can help reduce metabolic heat production. Shift feeding to the cooler morning and evening hours. For broilers, use a program that provides the majority of the daily ration during cooler periods. For layers, feed a larger portion of the daily ration in the evening. Do not withhold feed entirely for extended periods, as this can cause digestive upset and reduce performance. The goal is to shift feed intake to cooler times, not to reduce total intake. ## Related Farming Guides This section will be populated with links to related farming guides on poultry housing, ventilation, and flock management. Check back for additional resources on broiler production, layer management, and seasonal preparedness. ## Related Clinical & Scientific Guides * [Poultry Farm Fencing: Materials, Design, and Predator Exclusion](/knowledge/animal-farming/poultry/poultry-farm-fencing-materials-design-predator-exclusion) * [Broiler House Wind Speed and Airflow Measurement](/knowledge/animal-farming/poultry/broiler-house-wind-speed-airflow-measurement) * [Broiler House Heating Systems: Types and Efficiency](/knowledge/animal-farming/poultry/broiler-house-heating-systems-types-efficiency) ## References - FAO Poultry Production: https://www.fao.org/poultry-production-products/en/ - USDA APHIS Poultry Health: https://www.aphis.usda.gov/livestock-poultry-disease/avian - WOAH [Avian Influenza](/knowledge/bacteria/avian-bacteria/avian-influenza-cdc-guidelines-poultry-pandemic-preparedness): https://www.woah.org/en/disease/avian-influenza/ - FAO Animal Production and Health: https://www.fao.org/animal-production/en/ - WOAH (World Organisation for Animal Health): https://www.woah.org/en/home/ > This article is educational and is not a substitute for veterinary diagnosis, treatment, public-health guidance, or regulatory reporting.