# Ventilation Systems for Poultry Houses: Design and Management ## Key Takeaways - Poultry house ventilation is critical for bird health, growth, and performance, directly impacting respiratory disease, litter quality, and mortality by managing oxygen supply, moisture, ammonia, and temperature. - Minimum ventilation, essential in cold weather, utilizes small fans on timers (e.g., 0.5-1.0 CFM/bird for mature chickens) to continuously remove moisture and gases while preserving heat, requiring careful inlet management for proper air mixing. - Transitional ventilation employs side wall inlets and exhaust fans to manage moderate temperature fluctuations in spring and fall, balancing airflow for temperature control without the high velocities of tunnel ventilation. - Tunnel ventilation, the primary summer cooling system, uses large fans to create high air velocities (400-700 FPM) for wind chill effect, often augmented by evaporative cooling pads in dry climates to reduce effective temperature. - Maintaining optimal air quality requires continuous monitoring of temperature (e.g., 90-95°F for day-old chicks, decreasing with age), humidity (50-70% RH), ammonia (<25 ppm), and static pressure (0.05-0.12 inches of water column) to prevent respiratory compromise and performance degradation. - Effective ventilation management involves daily adjustments based on bird age, outdoor conditions, and sensor data, with specific protocols for winter (moisture removal, heat preservation), spring/fall (temperature swing management), and summer (heat stress mitigation). --- Poultry house ventilation is the single most important environmental factor in bird health, growth, and flock performance. Poor air quality leads to respiratory disease, wet litter, ammonia burns, reduced feed conversion, and higher mortality. This guide covers the principles of poultry barn ventilation design, the different ventilation stages, how to calculate ventilation rates for chickens, and how to manage your system through the seasons. It is written for commercial poultry growers, small flock owners, farm managers, and agricultural students who need practical, actionable information on designing, operating, and troubleshooting ventilation systems. ## At a Glance - **Ventilation has three jobs**: provide fresh oxygen, remove moisture and ammonia, and control temperature. - **Minimum ventilation** runs continuously in cold weather to remove moisture and gases while preserving heat. - **Transitional ventilation** uses side wall inlets and exhaust fans to manage temperature swings in spring and fall. - **Tunnel ventilation** moves high volumes of air for summer heat relief using large fans at one end and inlets at the other. - **A general rule** for minimum ventilation is 0.5 to 1.0 cubic feet per minute per bird for mature chickens, but exact rates depend on house size, bird age, and outdoor temperature. - **Static pressure** should be set between 0.05 and 0.12 inches of water column for most inlet systems. - **Ammonia levels** should stay below 25 parts per million. If you can smell ammonia, you are already above safe levels. - **Monitor daily**: temperature, humidity, ammonia, static pressure, fan operation, and bird behavior. - **Never rely on a single sensor**. Cross check digital readings with your own senses and physical checks. ## Why Ventilation Matters More Than You Think Birds breathe in oxygen and release carbon dioxide and water vapor. Their manure releases ammonia, and their activity generates heat. Without ventilation, a poultry house becomes a closed chamber of toxic gas, excess humidity, and heat. The consequences are not subtle. Poor air quality in poultry houses directly causes: - Respiratory irritation and disease - Wet litter and footpad lesions - Ascites and cardiovascular stress - Reduced feed intake and poor weight gain - Increased mortality - Higher rates of condemnations at processing The hidden cost of under ventilation is that birds look acceptable but perform far below genetic potential. Feed conversion suffers, and the flock takes longer to reach target weight. A ventilation system is not an operating expense that you can trim. It is the machinery of bird performance. ### The Four Main Pollutants Ventilation Removes **Ammonia** comes from microbial breakdown of uric acid in manure. It is heavier than air and concentrates near the floor where birds breathe. At 25 parts per million, ammonia impairs the immune system and damages the cilia in the respiratory tract. At 50 parts per million, feed intake drops visibly. At 100 parts per million, severe eye lesions and respiratory distress appear. Your nose is a useful tool: if you can smell ammonia, levels are likely above 25 parts per million. **Carbon dioxide** is produced by bird respiration and by litter decomposition. Levels above 3000 parts per million indicate inadequate ventilation. High carbon dioxide makes birds lethargic and reduces feed intake. **Moisture** is produced by bird respiration, manure moisture, and spilled water. A mature broiler flock can produce several thousand gallons of water vapor per day. If this moisture is not removed, litter becomes wet, ammonia production increases, and pathogens thrive. **Heat** is produced by bird metabolism. A house full of mature birds generates enormous heat, especially in summer. Without adequate air movement, birds suffer heat stress, pant, reduce feed intake, and die in severe cases. ## Understanding the Three Stages of Ventilation Poultry barn ventilation design is not one system. It is three systems that work together to manage different conditions. Every good ventilation system operates in one of three stages depending on outdoor temperature and bird age. ### Minimum Ventilation Minimum ventilation is the system that runs in cold weather when you need to preserve heat while still removing moisture and gases. It is not optional. Even in the dead of winter, birds produce moisture and carbon dioxide that must be removed. Minimum ventilation uses the smallest fans in the house, running on timers or a cycle controller. The goal of minimum ventilation is to remove moisture and ammonia while maintaining indoor temperature. The air exchange rate is low, typically 0.5 to 1.0 cubic feet per minute per bird for mature birds, and less for young chicks. The system runs in short bursts, often 30 to 60 seconds out of every 5 to 10 minutes, depending on conditions. Critical to minimum ventilation is the inlet system. Inlets must be adjusted so that incoming cold air enters at high velocity and travels along the ceiling before dropping to floor level. This allows the cold air to mix with warm air at ceiling level before it reaches the birds. If inlets are too small or improperly positioned, cold air drops directly on the birds and chills them. ### Transitional Ventilation Transitional ventilation is used in mild weather when minimum ventilation cannot remove enough heat but tunnel ventilation is not yet needed. This stage uses side wall exhaust fans, usually a portion of the tunnel fans, combined with side wall inlets. In transitional mode, the house uses the side wall inlets on one side of the house while fans on the opposite side pull air across the house. This creates air movement at bird level without the high velocities of tunnel ventilation. Transitional ventilation is useful in spring and fall when daytime temperatures are moderate but the house needs more airflow than minimum ventilation provides. The key to successful transitional ventilation is matching inlet opening to fan capacity. If inlets are open too wide for the number of fans running, air velocity drops and air falls to the floor before mixing. If inlets are too small, static pressure rises and fan performance suffers. ### Tunnel Ventilation Tunnel ventilation is the summer cooling system. Large fans at one end of the house pull air through the entire building, creating wind chill effect at bird level. Inlets at the opposite end are fully open. Air velocity should reach 400 to 700 feet per minute at bird level in a well designed tunnel house. Tunnel ventilation works by wind chill. Moving air removes heat from the birds bodies and increases evaporative cooling from panting. At 500 feet per minute air velocity, the effective temperature on the birds can be reduced by 5 to 10 degrees Fahrenheit compared to still air. In very hot climates, tunnel ventilation is often combined with evaporative cooling pads. Air is drawn through wet pads before entering the house, lowering the air temperature by 10 to 20 degrees Fahrenheit. The combination of cool air and air movement keeps birds alive and producing during extreme heat. ## Designing a Poultry House Ventilation System If you are building a new house or retrofitting an old one, the design decisions you make will determine your success for the next 20 years. Poorly designed houses are expensive to operate and difficult to manage. Well designed houses are efficient and forgiving. ### Fan Capacity and Placement The first step in design is determining total fan capacity. For tunnel ventilation, you need enough fan capacity to move air at 400 to 700 feet per minute through the length of the house. Calculate the cross sectional area of the house in square feet, then multiply by the desired air velocity in feet per minute. That gives you the total cubic feet per minute required. 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 feet per minute, you need 160,000 cubic feet per minute of tunnel fan capacity. For minimum ventilation, you need a small portion of that capacity that can run on timers. A common design uses one or two small fans, typically 24 to 36 inch fans, dedicated to minimum ventilation. These fans should be placed evenly along one end or side of the house to distribute airflow. Tunnel fans are typically 48 or 54 inch fans mounted at one end of the house. They should be spaced evenly and have shutters that close tightly when not running. Fan placement should create a smooth column of air without turbulence or dead spots. ### Inlet Design Inlets are as important as fans. The purpose of an inlet is to control where air enters the house and at what velocity. Air entering through a properly adjusted inlet travels along the ceiling at 800 to 1200 feet per minute, mixing with warm ceiling air before dropping to bird level. Standard side wall inlets are hinged boards that open inward. The opening size is controlled by a cable and winch system or by an automatic controller connected to static pressure sensors. Each inlet should be sized to handle a specific amount of airflow based on the fan capacity it serves. A common rule is that each square foot of inlet opening handles approximately 800 cubic feet per minute of air at 0.10 inches of water column static pressure. So a fan moving 10,000 cubic feet per minute needs about 12.5 square feet of inlet opening. Inlet placement matters. Inlets should be located along both side walls, spaced evenly, and positioned so that incoming air travels along the ceiling. In tunnel mode, the tunnel inlets at the end of the house should be large enough to handle the full tunnel fan capacity without creating excessive static pressure. ### Static Pressure and Air Mixing Static pressure is the resistance to airflow measured in inches of water column. It tells you whether your inlets are properly matched to your fans. When static pressure is too low, air enters too slowly and falls to the floor before mixing. When static pressure is too high, fan performance suffers and air velocity through the inlets is too high, creating drafts. For most side wall inlet systems, target static pressure is 0.05 to 0.12 inches of water column. The exact target depends on inlet design and ceiling angle. A steep ceiling pitch allows higher static pressure because the air jet can travel along the ceiling without dropping. A shallow ceiling requires lower static pressure. The jet of air entering through an inlet should travel at least 10 to 15 feet along the ceiling before it loses velocity and drops. If the house is narrow, this is easier to achieve. If the house is wide, you may need higher inlet velocity or additional stirring fans to keep air moving. ### Evaporative Cooling Pads In hot climates, evaporative cooling pads are a standard component of tunnel ventilation systems. Pads are installed at the tunnel inlet end of the house. Water is pumped over the pads, and incoming air is drawn through the wet pad material. As water evaporates, it cools the air. Pad systems require regular maintenance. The water distribution system must be checked for clogged nozzles and even flow. The pad material must be cleaned to remove mineral buildup and algae. Water quality matters: hard water leaves mineral deposits that reduce pad efficiency. Evaporative cooling works best in dry climates. In humid conditions, the cooling effect is reduced because the air is already saturated with moisture. In very humid regions, rely more on air velocity and less on evaporative cooling. ## Calculating Ventilation Rates for Chickens Ventilation rate for chickens is not a fixed number. It changes with bird age, bird weight, outdoor temperature, and house conditions. You must calculate and adjust rates regularly. ### Minimum Ventilation Rate Calculation The minimum ventilation rate is based on moisture removal. The goal is to remove the moisture produced by the birds and their manure while maintaining acceptable indoor humidity, typically 50 to 70 percent relative humidity. A practical starting point for mature birds is 0.5 to 1.0 cubic feet per minute per bird. For young chicks, the rate is lower, often 0.1 to 0.3 cubic feet per minute per bird, because they produce less moisture and need more heat. To calculate the total minimum ventilation rate for your house, multiply the number of birds by the rate per bird. For example, a house with 20,000 broiler chickens at 0.75 cubic feet per minute per bird needs 15,000 cubic feet per minute of minimum ventilation capacity. However, the rate must be adjusted based on outdoor temperature and litter conditions. When outdoor temperature is very low, you run less ventilation to preserve heat. When litter becomes wet, you must increase ventilation to dry it out. ### Timer Settings for Minimum Ventilation Minimum ventilation fans typically run on a timer cycle. The controller cycles the fans on for a set number of seconds and off for a set number of seconds. The on time is adjusted based on conditions. A common starting point is 30 seconds on out of every 5 minutes, meaning the fan runs 30 seconds and is off for 4 minutes 30 seconds. This gives 10 percent run time. If the fan moves 10,000 cubic feet per minute, the actual ventilation rate is 1,000 cubic feet per minute averaged over the cycle. To calculate timer settings, determine the total ventilation rate needed per minute, then divide by the fan capacity to get the fraction of time the fan must run. For example, if you need 1,500 cubic feet per minute and your fan moves 10,000 cubic feet per minute, the fan must run 15 percent of the time. Over a 5 minute cycle, that is 45 seconds on and 4 minutes 15 seconds off. In cold weather, run shorter cycles more frequently to maintain even air distribution. A 5 minute cycle with 30 to 60 seconds on is typical. In very cold weather, you may need to reduce the off time to keep moisture from building up. ### Transitional Ventilation Rates Transitional ventilation is based on temperature control rather than moisture removal. The goal is to maintain a target house temperature by bringing in enough air to remove excess heat. A starting point for transitional ventilation is 2 to 4 cubic feet per minute per bird. This moves more air than minimum ventilation but less than tunnel ventilation. As outdoor temperature rises, you increase the number of fans running and open inlets accordingly. The transition from minimum to transitional ventilation happens when minimum ventilation fans running continuously cannot maintain the target temperature. At that point, you turn on additional fans and adjust inlets. ### Tunnel Ventilation Rates Tunnel ventilation rates are based on air velocity. The target is 400 to 700 feet per minute at bird level. To calculate the required fan capacity, multiply the cross sectional area of the house by the target velocity. For example, a house 40 feet wide with an average height of 8 feet has a cross sectional area of 320 square feet. At 500 feet per minute, you need 160,000 cubic feet per minute of fan capacity. The transition to tunnel ventilation happens when transitional ventilation cannot maintain the target temperature with all transitional fans running. At that point, you open the tunnel inlets fully and turn on tunnel fans. ## Managing Your Ventilation System Through the Seasons Ventilation management is not set and forget. You must adjust your system daily, sometimes hourly, as conditions change. The following guidance applies to broiler and layer houses in temperate climates. ### Winter Management In winter, the primary challenge is removing moisture while preserving heat. The house should be tight, with no unintended air leaks. All fans and shutters should close tightly when not running. Cracks around doors and openings should be sealed. Run minimum ventilation continuously, adjusting timer settings based on indoor humidity and ammonia levels. Target indoor relative humidity of 50 to 60 percent. If humidity rises above 70 percent, increase ventilation. If humidity falls below 40 percent, you can reduce ventilation to save heat. Check ammonia levels daily, especially in the morning when the house is coldest. Ammonia levels above 25 parts per million require increased ventilation. If ammonia persists despite increased ventilation, the litter may be too wet or too deep, and you may need to remove some litter. Be careful not to over ventilate in winter. Excess ventilation wastes heat and increases fuel costs without improving bird health. The goal is to remove moisture and gases, not to cool the house. ### Spring and Fall Management Spring and fall are the most challenging seasons for ventilation management. Outdoor temperatures swing widely between day and night. A house that needs minimum ventilation in the morning may need transitional ventilation by afternoon. The key to successful spring and fall management is to anticipate changes and adjust early. Check weather forecasts and adjust your ventilation plan accordingly. If a warm day is forecast, start transitional ventilation early rather than waiting for the house to overheat. Use temperature controllers to automate the transition between stages. Modern controllers can be set to start additional fans as temperature rises and to shut them off as temperature falls. However, you must still monitor the system and make manual adjustments when conditions are unusual. ### Summer Management In summer, the challenge is heat removal. Tunnel ventilation should be running whenever outdoor temperature exceeds the target house temperature. In very hot weather, combine tunnel ventilation with evaporative cooling. Start tunnel ventilation early in the day, before the house heats up. It is easier to keep a house cool than to cool it down once it has overheated. Run tunnel fans at full capacity during the hottest part of the day, typically from mid morning to late afternoon. Use evaporative cooling pads when outdoor temperature exceeds about 85 degrees Fahrenheit and humidity is below 70 percent. In humid conditions, run tunnel fans without cooling pads to maximize air velocity. Monitor birds for signs of heat stress: panting, spreading wings, reduced activity, and clustering near drinkers. If birds are panting heavily, increase air velocity or start evaporative cooling. In extreme heat, reduce feed during the hottest part of the day to lower metabolic heat production. ## Monitoring Air Quality in Poultry Houses You cannot manage what you do not measure. Regular monitoring of air quality in poultry houses is essential for bird health and performance. The following parameters should be checked daily, and some continuously. ### Temperature Temperature should be monitored continuously using sensors placed at bird level. Place sensors every 50 to 100 feet along the house, at least one per room or section. Check sensor accuracy regularly by comparing readings with a calibrated thermometer. Target temperature depends on bird age. Day old chicks need 90 to 95 degrees Fahrenheit. The target decreases by about 5 degrees per week as birds grow. Mature birds are comfortable at 65 to 75 degrees Fahrenheit, with some variation by breed and management system. ### Humidity Relative humidity should be monitored continuously. Target range is 50 to 70 percent. Below 50 percent, litter becomes dusty and respiratory irritation increases. Above 70 percent, litter becomes wet and ammonia production increases. Humidity sensors should be placed away from drinkers and water lines to avoid false readings. Check sensors regularly and recalibrate as needed. ### Ammonia Ammonia should be checked at least twice daily, more often if levels are a concern. Use a handheld ammonia meter or gas detection tubes. Place the sensor at bird level, not at human height, because ammonia is heavier than air and concentrates near the floor. If ammonia exceeds 25 parts per million, increase ventilation immediately. If ammonia remains high despite increased ventilation, investigate the cause. Wet litter, deep litter, and leaking drinkers are common causes of high ammonia. ### Carbon Dioxide Carbon dioxide is a good indicator of overall ventilation adequacy. Levels above 3000 parts per million indicate insufficient air exchange. Measure carbon dioxide at bird level using a handheld meter. ### Static Pressure Static pressure should be monitored continuously when using side wall inlets. A static pressure sensor connected to the inlet controller automatically adjusts inlet openings to maintain the target pressure. Check the sensor regularly and verify that inlets are actually moving when the controller calls for adjustment. ### Fan Operation Check fans daily for proper operation. Look for belts that are worn or slipping, shutters that stick, and fan blades that are dirty. Clean fan blades and shutters regularly to maintain airflow. A dirty fan blade can reduce airflow by 30 percent or more. ## Common Ventilation Mistakes and How to Avoid Them Every poultry grower makes ventilation mistakes, especially when learning. The following are the most common problems and how to correct them. ### Inlet Misadjustment The most common ventilation mistake is improper inlet adjustment. Inlets that are too small create high static pressure and high air velocity, causing drafts. Inlets that are too large create low static pressure and low air velocity, causing air to fall to the floor before mixing. The solution is to match inlet opening to fan capacity. When you turn on a fan, observe the static pressure and adjust inlets until the pressure is in the target range. Check inlet adjustment whenever you change the number of fans running. ### Relying on Timers Instead of Sensors Some growers set minimum ventilation timers and never adjust them. This is a mistake because conditions change constantly. A timer setting that was correct in the morning may be wrong by afternoon. Use timers as a starting point, but adjust based on sensor readings and bird behavior. Check humidity and ammonia levels daily and adjust timer settings accordingly. ### Ignoring Air Leaks Air leaks are a major source of ventilation inefficiency. Unsealed cracks, gaps around doors, and poorly fitting shutters allow cold air to enter in winter and hot air to enter in summer. This creates drafts and makes the ventilation system work harder. Inspect the house regularly for air leaks and seal them promptly. Pay special attention to fan shutters, which are common sources of leakage. ### Over Ventilating in Cold Weather Some growers over ventilate in winter because they are worried about ammonia and moisture. This wastes heat and increases fuel costs without improving bird health. The goal of minimum ventilation is to remove moisture and gases while preserving heat. If humidity is in the target range and ammonia is below 25 parts per million, you are ventilating adequately. Do not increase ventilation just because you can. ### Under Ventilating in Warm Weather The opposite mistake is under ventilating in warm weather. Some growers wait until the house is visibly hot before turning on tunnel fans. This is inefficient and stressful for the birds. Start tunnel ventilation early in the day, before the house heats up. It is much easier to keep a house cool than to cool it down. ### Neglecting Fan Maintenance Dirty fans move less air. Worn belts slip and reduce fan speed. Shutters that stick reduce airflow and create drafts. Regular maintenance is essential for ventilation system performance. Clean fan blades and shutters at least monthly, more often in dusty conditions. Check belts and replace them when worn. Lubricate fan motors according to manufacturer recommendations. ### Ignoring Bird Behavior Your birds are the best indicator of ventilation adequacy. Birds that are panting are too hot. Birds that are huddled are too cold. Birds that are spread out and active are comfortable. Learn to read bird behavior and adjust ventilation accordingly. If birds are panting, increase ventilation. If birds are huddled, reduce ventilation or adjust inlets to eliminate drafts. ## Recordkeeping for Ventilation Management Good recordkeeping helps you identify problems early and make better management decisions. Keep a daily log of the following: - Outdoor temperature and humidity - Indoor temperature and humidity at multiple locations - Ammonia levels - Carbon dioxide levels - Static pressure - Number of fans running and their settings - Timer settings for minimum ventilation - Bird behavior observations - Feed and water consumption - Mortality Review your records weekly to identify trends. For example, if ammonia levels have been creeping up over several days, the litter may be getting wetter and you need to increase ventilation. If indoor temperature has been running higher than target, you may need to transition to the next ventilation stage earlier. Records also help you troubleshoot problems. If a flock performs poorly, your ventilation records can show whether environmental conditions were within acceptable ranges. ## Troubleshooting Ventilation Problems When birds are performing poorly, the ventilation system is often the culprit. Use the following troubleshooting guide to identify and correct problems. ### Birds Are Panting Panting indicates heat stress. Check that tunnel ventilation is running at full capacity. Check that tunnel inlets are fully open. Check that evaporative cooling pads are working properly. Increase air velocity by turning on additional fans. If birds are still panting with full tunnel ventilation, the house may have an airflow obstruction. Check for curtains that are closed, partitions, or equipment blocking the airflow path. Remove obstructions and ensure a clear path from inlets to fans. ### Birds Are Huddled Huddling indicates chilling. Check for drafts caused by improper inlet adjustment or air leaks. Check that minimum ventilation is not over ventilating. Reduce ventilation rate and adjust inlets to ensure incoming air mixes at the ceiling before reaching the birds. ### Ammonia Levels Are High High ammonia indicates inadequate ventilation or wet litter. Increase ventilation first. If ammonia remains high, check for wet litter caused by leaking drinkers, high humidity, or excessive manure moisture. Fix the source of moisture and increase ventilation to dry the litter. ### Litter Is Wet Wet litter is caused by excessive moisture in the house. Increase ventilation to remove moisture. Check drinkers for leaks and adjust drinker pressure to minimize water spillage. If litter is already wet, you may need to remove the wet litter and replace it with fresh litter. ### Temperature Is Uneven Across the House Uneven temperature indicates poor air distribution. Check that inlets are evenly adjusted and that fans are working properly. Check for obstructions that block airflow. In tunnel houses, check that the air velocity is uniform across the width of the house. ### Static Pressure Is Too High or Too Low High static pressure indicates that inlets are too small for the number of fans running. Open inlets wider or turn off some fans. Low static pressure indicates that inlets are too large. Close inlets or turn on additional fans. ## When to Call a Veterinarian or Extension Agent Most ventilation problems can be solved with adjustments and maintenance. However, some situations require professional assistance. ### Call a Veterinarian If - Mortality is suddenly elevated above normal levels - Birds show signs of respiratory distress, such as gasping, coughing, or nasal discharge - Birds are lethargic and not eating or drinking - You suspect an infectious disease outbreak - Birds have eye lesions or swollen heads, which may indicate high ammonia exposure or respiratory disease A veterinarian can help diagnose disease, recommend treatment, and advise on biosecurity measures. Early intervention is critical to minimize losses. ### Call an Extension Agent If - You are designing a new ventilation system or retrofitting an existing one - You are consistently unable to maintain target temperature or humidity despite correct procedures - You need help calculating ventilation rates for your specific house - You are experiencing unexplained poor performance that you cannot diagnose - You want to learn about new ventilation technology or management practices Extension agents have access to research and technical resources that can help you improve your ventilation system. They can also connect you with other growers who have solved similar problems. ### Call an Equipment Dealer or Manufacturer If - Fans are not operating properly despite maintenance - Controllers are malfunctioning - Sensors are giving inconsistent readings - You need replacement parts or upgrades Keep contact information for your equipment dealers handy and do not hesitate to call for technical support. ## Frequently Asked Questions ### How often should I run minimum ventilation in winter? Minimum ventilation should run continuously on a timer cycle, typically 30 to 60 seconds on and 4 to 5 minutes off. The exact settings depend on bird age, bird number, outdoor temperature, and indoor humidity. Adjust the timer settings to maintain indoor relative humidity between 50 and 60 percent. If humidity rises above 70 percent, increase the on time. If humidity falls below 40 percent, decrease the on time. ### What is the ideal ammonia level in a poultry house? Ammonia should be kept below 25 parts per million at bird level. At this level, ammonia is barely detectable by smell. If you can smell ammonia, levels are likely above 25 parts per million and you need to increase ventilation. Chronic ammonia exposure damages the respiratory tract and increases susceptibility to disease. ### How do I know when to switch from minimum to transitional ventilation? Switch from minimum to transitional ventilation when minimum ventilation fans running continuously cannot maintain the target house temperature. This typically happens when outdoor temperature rises above about 50 to 60 degrees Fahrenheit, depending on bird age and heat production. Start by turning on one additional fan and adjusting inlets. Add more fans as needed to maintain temperature. ### What static pressure should I maintain for side wall inlets? Target static pressure is typically 0.05 to 0.12 inches of water column, with 0.08 to 0.10 being common for many houses. The exact target depends on inlet design, ceiling angle, and house width. Higher static pressure creates higher inlet air velocity, which helps air travel along the ceiling before dropping to bird level. Adjust static pressure based on observed air mixing and bird comfort. ### How much air velocity do I need in tunnel ventilation? Target air velocity is 400 to 700 feet per minute at bird level. Higher velocities provide more cooling effect but require more fan capacity and increase static pressure. In hot climates, aim for the upper end of the range. In moderate climates, 400 to 500 feet per minute may be sufficient. Measure air velocity at multiple locations to ensure even distribution. ### Can I use fans to dry wet litter? Yes, increasing ventilation is the primary method for drying wet litter. However, you must also fix the source of moisture. Check for leaking drinkers, high water pressure, and excessive humidity. Increase minimum ventilation to remove moisture, and consider stirring the litter to aid drying. If litter is severely wet, remove it and replace with fresh litter. ### How do I clean and maintain evaporative cooling pads? Clean cooling pads at least monthly during the cooling season. Remove the pads and rinse them with clean water to remove dust and debris. Use a mild detergent if there is mineral buildup or algae growth. Check the water distribution system for clogged nozzles and ensure even water flow across the entire pad. Replace pads when they become worn or clogged beyond cleaning. ### What is the best way to measure air quality in my poultry house? Use a combination of continuous monitoring and spot checks. Install temperature and humidity sensors at bird level throughout the house, connected to your controller. Use a handheld ammonia meter or gas detection tubes for daily ammonia checks. Use a carbon dioxide meter for periodic checks. Cross check sensor readings with your own senses: if the air smells bad or feels stuffy, something is wrong. ## Related Farming Guides This section will be populated with links to related farming guides programmatically after generation. Check back for additional resources on poultry management, animal health, and farm infrastructure. ## 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](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.