Swine Barn Cooling Systems: Design and Management

By Dr. Zubair Khalid, DVM, MS, PhD · 2026-08-14

Key Takeaways

• Heat stress significantly reduces swine performance, lowering feed intake, growth rates, and feed efficiency by 10-20% and 5-10% respectively, and severely impacts reproduction, reducing conception rates and litter sizes. Pigs experience heat stress starting around 70°F (sows) to 75°F (finishing pigs), with the Temperature Humidity Index (THI) above 74 indicating mild stress and above 84 indicating severe stress.
• Adequate ventilation is foundational; tunnel ventilation with air speeds of 500-700 feet per minute at pig level is crucial for removing heat, moisture, and gases, with capacity requirements ranging from 500-800 CFM per finishing pig to 800-1000 CFM per sow.
• Evaporative cooling, primarily through cooling pads and high-pressure fogging, is most effective in dry climates by utilizing water evaporation to lower air temperature; cooling pads can reduce incoming air temperature by 10-20°F, while fogging systems require high pressure (800-1200 psi) and extremely clean water to prevent nozzle clogging.
• Drip cooling systems, delivering 0.5-1.5 gallons per hour per sow directly to the neck and shoulders, are highly effective and cost-efficient for gestating sows and farrowing crates, targeting individual animals without excessively wetting piglets.
• Water quality is paramount; hard water (above 100 ppm) and iron (above 0.3 ppm) necessitate water treatment (softening or reverse osmosis) to prevent scale buildup, pad degradation, and nozzle clogging, requiring weekly cleaning of pads and nozzles during hot seasons.
• A robust emergency plan, including backup power, spare parts, and a written response protocol for signs of severe heat stress (panting, lethargy), is critical, as pigs can succumb to heat stroke within hours without intervention.

Heat stress costs swine producers more money each year than most other environmental challenges combined. When pigs get hot, they eat less, grow slower, convert feed less efficiently, and struggle to reproduce. Sows abort or farrow smaller litters. Boars produce poorer semen. Finishing pigs take days longer to reach market weight. This guide explains how to design, install, operate, and troubleshoot swine barn cooling systems so you can protect your herd and your bottom line during hot weather.

This article is written for swine producers, farm managers, and animal care staff who want practical, actionable information on pig barn cooling systems. It covers the science behind heat stress, the main types of evaporative cooling for pigs, step-by-step design and management guidance, common mistakes, monitoring practices, and decision thresholds for when to call in professional help.

At a Glance

Understanding Heat Stress in Pigs

Pigs cannot sweat. They have very few functional sweat glands, so they rely on other methods to shed body heat. They pant, they seek cooler surfaces, they wallow in mud or water, and they reduce their activity. When the air temperature approaches their body temperature, these natural methods stop working well.

The thermoneutral zone is the range of temperatures where a pig does not have to expend extra energy to stay warm or cool down. For a 150 pound growing pig, that zone sits roughly between 60°F and 75°F. For sows, the upper end is closer to 70°F. For piglets, it is much warmer, around 85°F to 95°F, because they need supplemental heat. When the temperature rises above the upper critical temperature, the pig must work to cool itself, and that work costs energy that would otherwise go into growth, milk production, or fetal development.

Relative humidity matters just as much as air temperature. Pigs cool themselves through evaporation from their lungs and respiratory tract. When humidity is high, evaporation slows down. A pig at 85°F with 40 percent humidity may be uncomfortable but manageable. The same pig at 85°F with 90 percent humidity is in serious trouble. The temperature humidity index (THI) combines both factors into a single number. Many swine specialists consider a THI above 74 to be the start of mild heat stress for finishing pigs and sows. A THI above 84 is considered severe.

The economic impact of heat stress goes far beyond what you can see on a thermometer. Research from commercial swine operations consistently shows that heat stressed finishing pigs eat less feed, gain less weight, and convert feed less efficiently. During the hottest months, average daily gain can drop by 10 to 20 percent compared to cool season performance. Feed conversion can worsen by 5 to 10 percent. For a 1,000 head finishing barn, that adds up to thousands of dollars in lost performance every summer.

Reproduction suffers even more dramatically. Heat stressed sows around breeding time have lower conception rates. Sows that get hot during late gestation produce smaller piglets and may farrow earlier than expected. Milk production drops, which means lighter weaning weights. Boars housed in hot conditions produce semen with lower sperm counts, poorer motility, and more abnormal cells. The effects on semen quality can last for four to six weeks after the heat stress ends.

The good news is that most of this damage is preventable with properly designed and managed cooling systems. The rest of this guide explains exactly how to do that.

Ventilation First: The Foundation of Any Cooling System

Before you invest in evaporative cooling pads, foggers, or drip lines, you must make sure your barn has adequate ventilation. No cooling system can overcome poor air exchange. Pigs produce heat, moisture, and gases like ammonia and carbon dioxide. If those cannot escape, the barn becomes a heat trap regardless of what cooling equipment you install.

Tunnel ventilation is the standard approach for modern swine barns in hot weather. The barn is designed so that air enters at one end through cooling pads or inlets and exits at the other end through high capacity exhaust fans. This creates a continuous airflow that carries heat and moisture out of the building. Air speed at pig level should reach 500 to 700 feet per minute in tunnel mode for finishing pigs. Sows and boars benefit from similar or slightly higher air speeds.

The total ventilation capacity you need depends on the weight of the animals in the barn and the climate where you live. A general guideline for tunnel ventilation is 800 to 1,000 cubic feet per minute (CFM) per sow in a breeding or gestation barn, and 500 to 800 CFM per finishing pig at market weight. Your barn designer or local extension agent can help you calculate the exact requirements for your facility.

Air inlets must be sized and positioned to deliver air where the pigs actually are. In tunnel barns, the inlet area should match the fan capacity so that air speed stays consistent. If inlets are too small, fans work harder and static pressure rises. If inlets are too large, air moves too slowly to create the cooling effect.

Exhaust fans must be kept clean and well maintained. Dirty shutters, worn belts, and dusty blades can cut fan performance by 20 to 30 percent. Check fan belts monthly and replace them when they show signs of cracking or wear. Clean fan blades and shutters at the start of each hot season and again midway through summer.

Evaporative Cooling for Pigs: How It Works

Evaporative cooling is the most common and cost effective method for cooling swine barns in hot, dry climates. The principle is simple: when water evaporates into the air, it absorbs heat and lowers the air temperature. The drier the incoming air, the more cooling you get. In humid climates, evaporative cooling provides less benefit because the air is already holding significant moisture.

There are two main types of evaporative cooling systems used in pig barns: evaporative cooling pads and high pressure fogging systems.

Evaporative Cooling Pads

Cooling pads, also called evaporative cooling cells, are installed at the air inlet end of a tunnel ventilated barn. Air is drawn through the wet pads before it enters the pig space. As the air passes through the moist pad material, water evaporates and the air temperature drops. A well designed pad system can lower incoming air temperature by 10 to 20 degrees Fahrenheit in dry conditions.

The most common pad materials are cellulose and aspen. Cellulose pads are more durable and more efficient, with a typical lifespan of five to ten years. Aspen pads are cheaper but break down faster and need replacement every one to three years. Pad thickness ranges from 4 to 12 inches. Thicker pads provide more cooling but also create more resistance to airflow, so your fans must be sized to handle the added static pressure.

Water is distributed across the top of the pads through a distribution pipe with holes or nozzles. The water flows down through the pad material and collects in a gutter or sump at the bottom. A pump recirculates the water from the sump back to the top. A float valve maintains the water level in the sump, and a bleed-off line removes a portion of the recirculating water to prevent mineral buildup.

The cooling efficiency of a pad system depends on the contact time between the air and the wet pad surface. Air moving too fast through the pads does not have enough time to cool. Air moving too slowly reduces the total volume of cooled air delivered to the barn. Most pad systems are designed for air velocities of 250 to 400 feet per minute through the pad face.

High Pressure Fogging Systems

Fogging systems use high pressure pumps to force water through very small nozzles, creating a fine mist of water droplets. The droplets evaporate in the air before they reach the pigs or the floor. This cools the air directly and also increases humidity, which can be a drawback in already humid conditions.

Fogging systems are typically installed inside the barn, either at the air inlet end or distributed along the length of the building. Nozzles are placed high enough that the mist has time to evaporate before settling on animals or bedding. Operating pressure is usually 800 to 1,200 psi. Nozzle orifices are very small, often 0.005 to 0.010 inches, which means water quality is critical. Any mineral content or particulate matter in the water will clog nozzles quickly.

Fogging systems work best when the air is dry and there is good airflow through the barn. In humid conditions, the mist does not evaporate fully and can wet the pigs and the floor. Wet floors increase the risk of slipping and can promote bacterial growth in the bedding or manure.

Choosing Between Pads and Fogging

The choice between cooling pads and fogging depends on your climate, your barn design, and your budget. Cooling pads are generally more effective at lowering air temperature in hot, dry climates. They also do not add moisture directly to the pig space, since the evaporation happens in the pad before the air enters the barn. Pads require a significant capital investment, however, and they take up space at the inlet end of the barn.

Fogging systems are less expensive to install and can be added to existing barns more easily. They work well in areas with moderate heat and low humidity. They are less effective in humid climates and can cause wet bedding or slippery floors if not managed carefully.

Some producers use both systems together. Pads cool the incoming air, while foggers provide a final boost inside the barn during the hottest part of the day. This approach works well in very hot, dry regions, but it requires careful control to avoid over-humidifying the barn.

Drip Cooling for Sows

Drip cooling is a targeted cooling method designed specifically for sows in gestation stalls and farrowing crates. The system consists of a water line with small drip nozzles or emitters positioned above each sow. Water drips slowly onto the sow's neck and shoulders, where it evaporates and removes body heat. The sow does not need to be soaked. A steady drip that wets the skin is enough to provide significant cooling.

Drip cooling is effective because it targets the sow directly rather than trying to cool the entire barn. Sows are particularly sensitive to heat stress because of their large body mass and high metabolic rate. A sow in a gestation stall cannot move to a cooler spot or wallow in mud. Drip cooling brings the cooling to her.

Flow rates for drip cooling typically range from 0.5 to 1.5 gallons per hour per sow. The water should drip onto the neck and shoulders, not the head or the udder. A single emitter per sow is usually sufficient, though some producers use two emitters for very large sows or in extreme heat.

Drip cooling can run continuously during hot weather, but many producers use an intermittent cycle to conserve water. A common approach is to run the drip system for 10 to 15 minutes, then turn it off for 15 to 20 minutes. The goal is to keep the sow's skin moist without creating puddles on the floor or soaking the bedding.

In farrowing crates, drip cooling must be managed carefully to avoid wetting the piglets. Piglets need warm, dry conditions, and a wet crate floor can chill them. Position the drip emitters so water falls on the sow's neck and shoulders, which are typically at the front of the crate, away from the piglet creep area. Check the system frequently to make sure emitters have not shifted or clogged.

Drip cooling is one of the most cost effective cooling investments you can make for a sow herd. The equipment is inexpensive, installation is simple, and water use is modest. Many producers report that drip cooling alone reduces heat stress symptoms in sows by a significant margin, even in barns that do not have full evaporative cooling.

Sprinkler and Mist Cooling for Finishing Pigs

Finishing pigs in group pens can benefit from sprinkler or mist systems that wet the animals directly. These systems are simpler and less expensive than full evaporative cooling pads. They work on the same principle: water evaporates off the pig's skin and removes body heat.

Sprinklers deliver larger droplets of water, similar to a light rain. They wet the pig's skin more thoroughly but also wet the floor and the pen. Sprinklers are typically mounted above the pens and run on an intermittent cycle. A common schedule is 2 to 5 minutes on, then 20 to 40 minutes off. The off period gives the water time to evaporate and the floor time to dry.

Mist systems deliver much finer droplets that evaporate more quickly. They wet the pigs less but cool the air more effectively. Mists are often used in combination with fans to create a wind chill effect. The fan moves air across the wet pig, accelerating evaporation and heat removal.

Both systems require careful management of water use and drainage. Wet pens can become muddy, which increases the risk of slipping and can harbor bacteria. Floors must have adequate slope and drainage to move excess water out of the pen. Solid floors need a drain or gutter. Slatted floors handle water better because the manure and water fall through the slots.

Sprinkler and mist systems are less efficient with water than drip cooling because they wet a larger area. They also add humidity to the barn air, which can reduce the effectiveness of other cooling systems. Use them only when the barn has strong ventilation to carry away the added moisture.

Cooling Pad Design and Installation Step by Step

If you are installing a new cooling pad system or upgrading an existing barn, follow these steps to get the design right.

Step 1: Calculate your barn's ventilation requirements. Determine the total CFM of exhaust fan capacity needed for your animal type, weight, and stocking density. Work with your barn designer or extension agent if you are unsure.

Step 2: Determine the pad area needed. Divide the total fan CFM by the desired air velocity through the pad, typically 250 to 400 feet per minute. For example, if your barn has 40,000 CFM of tunnel fan capacity and you want 300 feet per minute through the pad, you need 133 square feet of pad face area (40,000 divided by 300).

Step 3: Choose the pad material and thickness. Cellulose pads are the standard choice for permanent installations. A 6 inch pad provides good cooling with moderate static pressure. An 8 inch or 12 inch pad provides more cooling but requires more fan capacity. Consider your climate and how many days per year you will run the system.

Step 4: Position the pads correctly. Pads should be installed at the air inlet end of the barn, covering the full width of the inlet opening. The pad frame must be sealed so that all incoming air passes through the pads. Any gaps or bypass areas will let hot, uncooled air into the barn.

Step 5: Install the water distribution system. The distribution pipe runs along the top of the pads with holes or nozzles spaced to deliver water evenly across the pad face. The sump at the bottom collects the water and connects to the recirculation pump. Install a float valve to maintain water level and a bleed line to control mineral concentration.

Step 6: Connect the controls. The system should run whenever the tunnel fans are running and the outside temperature is above the set point, typically 75 to 80 degrees Fahrenheit. A thermostat or controller can automate this. Manual override switches allow you to run the system when needed.

Step 7: Test the system before the hot season. Run water through the pads and check for even distribution across the entire pad face. Look for dry spots, which indicate clogged distribution holes or an uneven pad surface. Verify that the sump pump delivers adequate flow and that the bleed line is working.

Fogging System Design and Installation

Fogging systems require careful attention to water quality and nozzle placement. Follow these steps for a successful installation.

Step 1: Test your water quality. Fogging nozzles have very small orifices. High mineral content, especially calcium and magnesium, will clog nozzles and leave white scale on surfaces. If your water is hard, install a water softener or reverse osmosis system before the fogging pump.

Step 2: Determine the number and placement of nozzles. Nozzles should be spaced to provide even coverage along the length of the barn. In a tunnel barn, more nozzles near the inlet end help cool the incoming air. In a naturally ventilated barn, distribute nozzles evenly across the ceiling. A general guideline is one nozzle per 100 to 200 square feet of floor area, but the exact spacing depends on nozzle output and ceiling height.

Step 3: Install the high pressure pump and filtration. The pump must deliver the required pressure and flow rate for your nozzle count. Install a main filter and a filter at each zone or line. Use 0.5 micron filters or finer to protect the nozzles.

Step 4: Mount the nozzles high, at least 10 feet above the floor if possible. The mist needs distance to evaporate before reaching the pigs. In barns with low ceilings, fogging may not be practical because the droplets will not have time to evaporate.

Step 5: Set up the control system. A humidistat can prevent the system from running when humidity is already high. A thermostat activates the system when temperature rises above the set point. Many producers run foggers on an intermittent cycle, such as 30 seconds on and 2 to 3 minutes off, to control humidity buildup.

Step 6: Test thoroughly. Run the system and check for even mist distribution. Look for large droplets that fall quickly, which indicate a nozzle problem or insufficient pressure. Adjust the pressure and nozzle placement until you get a fine mist that hangs in the air.

Drip Cooling Installation Step by Step

Drip cooling is the simplest system to install, and you can often do it yourself with basic plumbing skills.

Step 1: Determine your water source and pressure. Drip systems operate at low pressure, typically 10 to 30 psi. If your barn water line runs at higher pressure, install a pressure regulator.

Step 2: Run a supply line along the row of stalls or crates. Use 1/2 inch or 3/4 inch PVC pipe or polyethylene tubing. Position the line so that emitters can reach the sow's neck and shoulders.

Step 3: Install drip emitters at each stall. Emitters come in fixed flow rates, typically 0.5, 1.0, or 2.0 gallons per hour. For most sows, 1.0 gallon per hour is a good starting point. You can adjust later based on the sow's response and the barn conditions.

Step 4: Position the emitter directly above the sow's neck and shoulders. In a gestation stall, this is usually about one third of the way back from the front of the stall. In a farrowing crate, position it so the water falls on the sow's neck, not on the piglet creep area.

Step 5: Install a timer or controller. A simple time clock can run the system on an intermittent schedule. More advanced controllers can integrate with your barn computer to run the drip system based on room temperature.

Step 6: Test each emitter individually. Walk the barn and verify that every emitter is delivering water at the correct rate. Clogged emitters are the most common problem, so check them weekly during the hot season.

Managing Water Quality for Cooling Systems

Water quality is the single most common cause of cooling system failure. Hard water, iron, and other minerals coat pads, clog nozzles, and scale up pipes. Poor water quality can turn a well designed cooling system into an expensive maintenance headache.

Test your water before you install any cooling equipment. Send a sample to a lab and check for total hardness, iron, manganese, and total dissolved solids. Hardness above 100 parts per million (ppm) is a concern for pad systems. Iron above 0.3 ppm will stain pads and clog nozzles. Total dissolved solids above 1,000 ppm can reduce evaporation efficiency.

If your water is hard, install a water softener for the cooling system supply. Softeners exchange calcium and magnesium for sodium, which does not form scale. For very hard water or high iron, consider a reverse osmosis system. These are more expensive but provide the cleanest water and the longest equipment life.

Even with good water, you need a maintenance routine. Cooling pads should be bled continuously to remove dissolved minerals. A bleed rate of 10 to 20 percent of the recirculating water flow is typical. This means that for every 100 gallons of water circulating, 10 to 20 gallons go down the drain and are replaced with fresh water.

Clean pads at the start of each season and again mid season. Use a mild acid cleaner designed for cooling pads. Do not use bleach or harsh chemicals that can damage the pad material. Rinse thoroughly after cleaning.

Fogging nozzles should be cleaned or replaced at the first sign of reduced output. Keep a supply of spare nozzles on hand. Soak clogged nozzles in a descaling solution and rinse before reinstalling.

Controlling the System: Thermostats, Timers, and Automation

A cooling system is only as good as its controls. A system that runs too little leaves pigs hot. A system that runs too much wastes water and can make the barn humid and uncomfortable.

The simplest control is a thermostat that turns the cooling system on when the barn temperature exceeds a set point. For finishing pigs, a common set point is 75 to 80 degrees Fahrenheit. For sows, use a lower set point of 70 to 75 degrees because sows are more sensitive to heat.

Timers add a second layer of control. They cycle the cooling system on and off to prevent over-wetting or over-humidifying. A typical cycle for drip cooling is 10 minutes on and 20 minutes off. For sprinklers, 3 minutes on and 30 minutes off. For foggers, 30 seconds on and 3 minutes off. The exact settings depend on your climate, your barn, and your animals.

Humidistats are valuable in humid climates. They measure the relative humidity and shut off evaporative cooling when humidity gets too high. This prevents the barn from becoming a steam bath. A humidistat set at 80 percent will stop the cooling system when the air reaches that humidity level.

Modern barn controllers can integrate all of these functions. They can monitor temperature, humidity, and animal age, then adjust cooling automatically. They can also send alerts to your phone if the system fails or the barn gets too hot. If you are building a new barn or upgrading an old one, invest in a good controller. It will pay for itself in avoided losses and reduced labor.

Managing Cooling During Different Production Stages

Different pigs have different cooling needs. A one size fits all approach will leave some animals too hot and others too cold.

Gestating Sows

Gestating sows are large, heavy animals with a low surface area to body weight ratio. They lose heat slowly and are very susceptible to heat stress. The critical period is the first 30 days after breeding, when heat stress can reduce embryo survival. Keep gestating sows comfortable throughout the summer with a combination of ventilation, drip cooling, and possibly evaporative cooling.

Farrowing Sows

Farrowing sows face a double challenge. They need to stay cool for their own health and milk production, but their piglets need temperatures of 85 to 95 degrees Fahrenheit. The solution is to cool the sow locally with drip cooling while providing a separate warm creep area for the piglets. Do not cool the entire farrowing room too aggressively, or the piglets will chill.

Nursery Pigs

Nursery pigs are smaller and more sensitive to drafts than finishing pigs. They do not need aggressive cooling in most climates. Good ventilation and moderate air movement are usually sufficient. Avoid using evaporative cooling in nurseries unless the climate is very hot and dry.

Finishing Pigs

Finishing pigs benefit most from tunnel ventilation and evaporative cooling. They have a large body mass and generate significant heat. Air speeds of 500 to 700 feet per minute at pig level make a big difference in their comfort. Sprinklers or misters can provide additional cooling during the hottest part of the day.

Boars

Boars need careful cooling because heat stress affects semen quality for weeks after the exposure. Keep boar studs cool with evaporative cooling or air conditioning in hot climates. Monitor semen quality and be aware that a heat wave this week can affect fertility next month.

Common Mistakes in Swine Barn Cooling

Many producers make the same mistakes when designing and managing cooling systems. Here are the most common ones and how to avoid them.

Mistake 1: Ignoring ventilation. Some producers install expensive cooling equipment in barns with inadequate ventilation. The cooling system cannot overcome poor air exchange. Fix the ventilation first, then add cooling.

Mistake 2: Undersizing the cooling system. A pad system that is too small cannot cool enough air to make a difference. A fogging system with too few nozzles produces spotty cooling. Calculate your needs carefully and add a margin of safety.

Mistake 3: Poor water quality. Hard water ruins pads and clogs nozzles. Test your water and treat it before it becomes a problem.

Mistake 4: Neglecting maintenance. Cooling systems need regular attention. Pads clog, nozzles plug, pumps fail, and belts wear out. Write a maintenance schedule and stick to it.

Mistake 5: Overcooling. Running evaporative cooling when the outside air is humid can make the barn wet and uncomfortable. Use a humidistat to prevent this.

Mistake 6: Wetting the bedding. Sprinklers and misters can soak bedding and create unhealthy conditions. Position nozzles carefully and use intermittent cycles to let things dry out.

Mistake 7: Forgetting about the piglets. In farrowing rooms, aggressive cooling can chill piglets. Always provide a warm, dry creep area separate from the sow's cooling zone.

Mistake 8: No backup plan. When the power goes out or the pump fails, pigs can die quickly. Have a backup generator, spare pumps, and a written emergency plan.

Monitoring and Recordkeeping

You cannot manage what you do not measure. Keep good records of your cooling system performance and your pigs' response to heat.

Track the following daily during the hot season:

• Outside temperature and humidity at the same time each day
• Barn temperature in several locations, not just one sensor
• Barn humidity
• Cooling system run time
• Water use for the cooling system
• Any equipment failures or maintenance performed

Track the following production metrics weekly:

• Feed intake per pig or per pen
• Average daily gain for finishing pigs
• Sow conception rate and farrowing rate
• Litter size and weaning weights
• Mortality and culling rates

Look for patterns. If feed intake drops every afternoon when the barn hits 85 degrees, your cooling system is not keeping up. If sow conception rates drop in August and September, your summer cooling may be inadequate.

Set alarms on your barn controller for high temperature and high humidity. Test the alarm system regularly to make sure it works. A silent alarm is no alarm at all.

Emergency Response for Heat Stress

Even with the best cooling system, emergencies happen. Power outages, pump failures, and extreme weather events can all create dangerous conditions for your herd. Have a written emergency plan before you need it.

The first sign of heat stress in pigs is increased respiration rate. Pigs start panting, breathing rapidly and shallowly. They seek out cool surfaces and lie spread out. As heat stress worsens, pigs become lethargic, refuse to eat, and may vomit. Severe heat stress causes open mouth breathing, reddened skin, and incoordination. Without intervention, pigs can die from heat stroke.

If you see signs of severe heat stress, act immediately:

1. Turn on all ventilation fans. If power is out, use a generator.
2. Wet the pigs with cool water using a hose or sprinkler. Focus on the head, neck, and shoulders.
3. Increase air movement with portable fans if available.
4. Move pigs to a cooler area if possible.
5. Call your veterinarian for guidance.

Prevention is always better than treatment. Before the hot season starts, check your generator, test your alarm system, and stock spare parts for your cooling equipment. Have a plan for how you will respond if the power goes out during a heat wave.

When to Call a Veterinarian or Extension Agent

Most cooling system problems are within the capability of a good farm manager to solve. But there are times when you need professional help.

Call your veterinarian if:

• Pigs show signs of severe respiratory distress that does not improve with cooling
• You see unusual death loss during hot weather
• Sow conception rates or litter sizes drop suddenly
• Pigs have persistent diarrhea or other signs of illness that may be related to heat stress
• You are unsure whether a sick pig has heat stress or an infectious disease

Call your extension agent or a barn design consultant if:

• You are designing a new barn and need help calculating ventilation and cooling requirements
• Your existing cooling system is not performing well and you cannot figure out why
• You are considering a major upgrade and want to evaluate your options
• You need help interpreting your production records and identifying heat related losses

Professional help is an investment, not an expense. A properly designed cooling system can save you thousands of dollars in lost production every summer.

Economic Considerations

Cooling systems cost money, but heat stress costs more. Consider the economics before you decide how much to invest in cooling.

The main costs of a cooling system are:

• Initial equipment cost
• Installation cost
• Water use
• Electricity for pumps and fans
• Maintenance and replacement parts

The main benefits are:

• Increased feed intake and average daily gain in finishing pigs
• Better feed conversion
• Higher sow conception rates and larger litters
• Higher weaning weights
• Better boar semen quality
• Lower mortality and culling rates

A simple way to evaluate an investment is to calculate the payback period. Divide the total cost of the system by the annual savings from improved production. If a drip cooling system costs $2,000 and saves $500 per year in improved sow performance, the payback period is four years. Most cooling systems have payback periods of one to five years in hot climates.

Water use is a real cost, especially in areas with limited water. Drip cooling uses about 0.5 to 1.5 gallons per hour per sow. A 1,000 sow barn running drip cooling 12 hours per day for 90 days uses about 540,000 to 1.6 million gallons per year. At typical rural water rates, this adds up to a few hundred to a few thousand dollars per year. Compare this to the value of the production you save, and the investment is usually justified.

Frequently Asked Questions

What temperature is too hot for pigs?

Pigs start feeling heat stress when the temperature exceeds their upper critical temperature, which is about 75 degrees Fahrenheit for finishing pigs and 70 degrees for sows. The combination of temperature and humidity matters more than temperature alone. When the temperature humidity index exceeds 74, pigs begin to show signs of heat stress. Above 84 is considered severe.

Does a fan alone cool pigs effectively?

Fans help by moving air across the pig's skin, which accelerates evaporative cooling from the respiratory tract and skin surface. Air movement of 500 to 700 feet per minute can make a significant difference in pig comfort. However, fans alone are not enough in extreme heat. When air temperature approaches body temperature, moving air cannot remove enough heat. Combining fans with evaporative cooling, drip cooling, or sprinklers is much more effective.

How much water does a drip cooling system use per sow?

A drip cooling system uses about 0.5 to 1.5 gallons per hour per sow, depending on the emitter flow rate and the operating schedule. A typical system running 12 hours per day uses 6 to 18 gallons per sow per day. This is a small amount of water compared to the value of the production you protect.

Can I use evaporative cooling in a humid climate?

Evaporative cooling is less effective in humid climates because the air already holds significant moisture. However, it can still provide some benefit, especially during the hottest part of the day when humidity is often lower. A humidistat can shut off the system when humidity gets too high. In very humid climates, air conditioning may be the only reliable way to cool pigs, but it is usually too expensive for swine barns.

How often should I clean my cooling pads?

Clean cooling pads at the start of the hot season and again midway through summer. Use a mild acid cleaner designed for cooling pads. Do not use bleach or other harsh chemicals. In addition to cleaning, run a continuous bleed line to remove dissolved minerals from the recirculating water. Check the pads weekly for dry spots, algae growth, or mineral buildup.

What is the best cooling system for a farrowing barn?

Drip cooling is the best choice for farrowing barns because it cools the sow without chilling the piglets. Position the drip emitter over the sow's neck and shoulders, away from the piglet creep area. Provide supplemental heat for the piglets in the creep area. Avoid aggressive evaporative cooling in farrowing rooms because it can make the whole room too cold for piglets.

How quickly do pigs die from heat stress?

Pigs can die from heat stress within hours in extreme conditions. The time depends on the temperature, humidity, pig size, and the pig's health status. Large pigs and sows are more susceptible than small pigs because they have more body mass to cool. Never leave pigs unattended during a heat wave without functioning cooling systems and a backup power plan.

Should I run my cooling system at night?

It depends on the overnight temperature. If the barn cools down below 75 degrees at night, you can often turn off evaporative cooling and rely on ventilation alone. Pigs benefit from a cool period at night to recover from daytime heat stress. If overnight temperatures stay above 80 degrees, continue running your cooling system.

Related Farming Guides

The following guides provide additional information on related swine management topics. They are populated automatically based on the current article category and search intent.

Related Clinical & Scientific Guides

• Pig Enrichment Programs and Behavior Monitoring
• Swine Handling Facility Design for Safe Pig Movement
• Swine Feeding Management for Grow-Finish Pigs

References

• National Pork Board: https://www.pork.org/
• USDA APHIS Swine Health: https://www.aphis.usda.gov/livestock-poultry-disease/swine
• FAO Pig Production: https://www.fao.org/pig-production-and-products/en/
• 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.