Your pigs and chickens in Vietnam are suffering. The air is hot and sticky. They cannot cool down. Your production drops.
A wet curtain cooling system lowers barn temperature by 5‑10°C using water evaporation. In Vietnam’s hot, humid climate, it is the most cost‑effective way to keep animals comfortable without high electricity bills.
I am Zora Guo from Yichen. My factory makes wet curtain cooling pads and exhaust fans. I have worked with many farms in Vietnam, from the Mekong Delta to the highlands near Da Lat. The problem is real. The solution works. Let me explain how.
Why Do Pig and Poultry Farms in Vietnam Need Wet Curtain Cooling Systems to Beat Heat and Humidity?
You walk into your barn. The air feels heavy. Animals are panting. You see pigs lying in their own waste to cool off. This is not good for them or your business.
Vietnamese farms need wet curtain cooling because the combination of high temperature (35‑38°C) and high humidity (70‑85%) creates deadly heat stress. Pigs stop eating, sows abort, chickens stop laying eggs, and broilers grow slowly. Wet curtains use evaporation to cool incoming air, even in humid conditions, though the effect is less than in dry climates.
Let me explain why Vietnam is a special challenge.
The Vietnamese Climate Problem
Vietnam has two seasons: the rainy season (May to October) and the dry season (November to April). Both are hot. But the rainy season is very humid. In the Mekong Delta, humidity often exceeds 85%. In the dry season, humidity drops to 50‑70%, but temperatures rise.
How heat builds up:
- The sun heats the metal roof.
- The roof radiates heat down to the animals.
- Animals produce their own body heat and moisture.
- Stale, humid air gets trapped inside.
Without cooling, barn temperatures can reach 40‑45°C. At that level, pigs and chickens stop growing.
How Wet Curtain Cooling Works
Wet curtain cooling (also called evaporative cooling) uses a simple principle: water evaporates and takes heat from the air.
Step by step:
- Hot outside air is pulled through wet cooling pads by exhaust fans.
- Water on the pads evaporates into the air.
- Evaporation absorbs heat from the air.
- The air temperature drops.
- Cool air enters the barn and flows over the animals.
Even in humid Vietnam, this works. The air may already be wet, but the pads can still cool it by 5‑7°C. That can be the difference between survival and death.
Effects of Heat Stress on Vietnamese Livestock
| Animal | Signs of heat stress | Economic loss |
|---|---|---|
| Piglets | Diarrhea, reduced feed intake | 20‑30% slower growth |
| Sows | Reduced milk, low conception rates | Fewer piglets born, higher mortality |
| Finishing pigs | Panting, aggression, reduced feed | Longer time to market weight |
| Broiler chickens | Panting, spreading wings, death | Up to 15% lower weight gain |
| Layers | Reduced egg production, thin shells | 10‑20% fewer eggs |
A pig farmer in Dong Nai province told me: “Before we installed wet curtains, our sows would abort in April and May. Now the barn stays cool. We get two more piglets per litter per year.”
Why Wet Curtains Are Better Than Fans Alone
Regular fans just move hot air. They do not cool. In fact, if the air is already hot, fans can make heat stress worse by blowing hot air on animals. Wet curtains actually lower the air temperature. That is why they are essential for serious farms in Vietnam.
How Much Temperature Drop Can You Realistically Expect from a Wet Curtain System in Vietnam’s Hot, Humid Climate?
You see ads that say “cools by 15°C.” That is for dry climates like Australia or the Middle East. Vietnam is different. You need honest numbers.
In Vietnam’s hot, humid conditions, a well‑designed wet curtain system typically drops the incoming air temperature by 5‑8°C. In the drier central highlands (e.g., Da Lat), you may get 8‑10°C. In the humid Mekong Delta, expect 4‑6°C. That drop is still enough to save your animals and improve productivity.
Let me give you real numbers from farms I have worked with.
Expected Cooling by Region
| Region | Typical humidity | Outside temp | Temperature drop | Cool air entering barn |
|---|---|---|---|---|
| Mekong Delta (Can Tho, Vinh Long) | 80‑90% | 33‑36°C | 4‑6°C | 27‑30°C |
| Southeast (Ho Chi Minh, Dong Nai) | 70‑80% | 34‑38°C | 5‑7°C | 27‑31°C |
| Central coast (Da Nang, Nha Trang) | 70‑80% | 33‑37°C | 5‑8°C | 26‑30°C |
| Central highlands (Da Lat, Buon Ma Thuot) | 60‑70% | 28‑33°C | 8‑10°C | 20‑24°C |
| North (Hanoi, Hai Phong) | 75‑85% | 32‑36°C | 5‑7°C | 26‑30°C |
Factors That Affect Your Actual Cooling
- Pad thickness – 100mm pads cool more than 75mm pads. I recommend 150mm for Vietnam.
- Pad condition – Old, clogged pads cool poorly. Replace every 2‑3 years.
- Air speed – Too fast reduces cooling. Keep air speed under 2 m/s through pads.
- Water quality – Hard water leaves mineral deposits. Use filtered or soft water if possible.
- Humidity – On rainy days, cooling is less. But on those days, the outside temperature is also lower.
A Real Example from a Pig Farm in Binh Duong
A farm with 500 sows installed a wet curtain system with 150mm pads and 8 exhaust fans. In April (dry season), outside temperature was 37°C with 60% humidity. The air coming through the pads measured 28°C. That is a 9°C drop.
In September (rainy season), outside was 33°C with 85% humidity. The cool air was 28°C. Only a 5°C drop. But the owner said: “That 5°C is enough. Before the system, the barn was 35°C. Now it is 30°C. The pigs are not panting anymore.”
What If Cooling Is Not Enough?
If you need more cooling, combine wet curtains with roof insulation or sprinklers on the roof. Or use a two‑stage cooling system (first stage wet curtain, second stage chilled water, but that is expensive). For most Vietnamese farms, a single stage wet curtain is enough.
How Do Wet Curtain Cooling Costs Compare to Air Conditioners or Diesel‑Powered Fans for Vietnamese Farms?
You look at the price of a wet curtain system. It might be 50‑100 million VND ($2,000‑4,000). Then you look at air conditioners. They seem cheaper per unit. But you must consider running costs.
Wet curtain cooling costs much less to run than air conditioners or diesel fans. A wet curtain system for a 500m² barn uses about 5‑10 kWh of electricity per day (for fans and water pump). An air conditioner for the same area would use 200‑400 kWh per day. Diesel fans cost even more due to fuel. Over one hot season, wet curtains can save you 70‑90% on cooling energy costs.
Let me break down the numbers.
Initial Investment (Upfront Cost)
| System | Equipment cost for 500m² barn | Installation cost | Total upfront |
|---|---|---|---|
| Wet curtain + exhaust fans | $2,500‑4,000 | $500‑1,000 | $3,000‑5,000 |
| Split AC units (5 units) | $4,000‑6,000 | $1,000‑2,000 | $5,000‑8,000 |
| Diesel fans (6 units) | $1,500‑2,500 | $200‑500 | $1,700‑3,000 |
Diesel fans seem cheapest upfront. But wait.
Daily Operating Cost (Based on 10 hours/day)
| System | Electricity/diesel use | Cost per day | Cost per hot season (90 days) |
|---|---|---|---|
| Wet curtain (fans + pump) | 6 kWh (at 2,500 VND/kWh) | 15,000 VND ($0.65) | 1,350,000 VND ($58) |
| AC units (5 units x 1.5 kW each) | 75 kWh | 187,500 VND ($8.15) | 16,875,000 VND ($733) |
| Diesel fans (6 units x 0.5L/h each) | 30L diesel at 25,000 VND/L | 750,000 VND ($32.60) | 67,500,000 VND ($2,934) |
Savings: Wet curtain saves you 16.5 million VND ($717) per season compared to AC, and 66 million VND ($2,870) compared to diesel.
Payback Time
The extra upfront cost of wet curtain vs diesel fans is about $1,300. But you save $2,870 per season in fuel. So payback is less than half a season.
Additional Benefits
- No noise – Wet curtains are quiet. Diesel fans are loud and stress animals.
- No exhaust fumes – Diesel fumes are bad for animal health.
- Lower maintenance – AC units need regular cleaning of filters and refrigerant refills. Diesel fans need oil changes, filter changes, and engine repairs.
- Better for the environment – Lower carbon footprint.
A Real Example from a Poultry Farm in Long An
A farmer had 20,000 broilers. He used 6 diesel fans. His fuel bill in April was 15 million VND ($650). He switched to a wet curtain system with 4 electric fans. His electricity bill for cooling was 1.2 million VND ($52) per month. He saved 13.8 million VND ($600) per month. The system paid for itself in 3 months.
He told me: “I wish I had switched earlier. The diesel fans also broke down twice. The wet curtain has run every day with no problems.”
What Simple Maintenance (Algae Control, Water Quality, Pad Cleaning) Keeps Wet Curtains Working Efficiently in Vietnam?
You install your wet curtain. It works great for a month. Then you notice green slime on the pads. The water smells. Cooling drops. This is algae, and it grows fast in Vietnam’s warmth.
To keep wet curtains working in Vietnam, flush the pads weekly with clean water, add a small amount of algaecide to the tank monthly, clean the water tank every two weeks, and replace pads every 2‑3 years. Also, use a pre‑filter on the water line to stop sand and debris from clogging the distribution system.
Let me give you a simple schedule that works with local resources.
Maintenance Schedule
| Task | Frequency | Time needed | Tools |
|---|---|---|---|
| Visual check of [pads](https://en.aviagen.com/assets/Tech_Center/BB_Resources_Tools/Ventilation_How_Tos/AAVentHowTo06-CleanEvaporativeCoolingPadsAndSys ... [TRUNCATED, (original length: 140 chars)]") and [water flow](https://en.aviagen.com/assets/Tech_Center/BB_Resources_Tools/Ventilation_How_Tos/AAVentHowTo06-CleanEvaporativeCoolingPadsAndSys ... [TRUNCATED, (original length: 140 chars)]") | Daily | 5 minutes | None |
| Flush [pads](https://en.aviagen.com/assets/Tech_Center/BB_Resources_Tools/Ventilation_How_Tos/AAVentHowTo06-CleanEvaporativeCoolingPadsAndSys ... [TRUNCATED, (original length: 140 chars)]") with clean water | Weekly | 15 minutes | Garden hose |
| Clean water tank (drain, scrub, rinse) | Every 2 weeks | 30 minutes | Brush, bucket |
| Check and clean [water distribution holes](https://en.aviagen.com/assets/Tech_Center/BB_Resources_Tools/Ventilation_How_Tos/AAVentHowTo06-CleanEvaporativeCoolingPadsAndSys ... [TRUNCATED, (original length: 140 chars)]") | Monthly | 20 minutes | Toothbrush or small wire |
| Add algaecide to tank | Monthly | 2 minutes | Measuring cup |
| Check pump and fan belts | Monthly | 10 minutes | Wrench |
| Deep clean pads (remove and rinse) | Every 6 months | 1‑2 hours | Pressure washer (low pressure) |
| [Replace pads](https://en.aviagen.com/assets/Tech_Center/BB_Resources_Tools/Ventilation_How_Tos/AAVentHowTo06-CleanEvaporativeCoolingPadsAndSys ... [TRUNCATED, (original length: 140 chars)]") | Every 2‑3 years | 2‑3 hours | New pads, basic tools |
Algae Control – The Biggest Issue in Vietnam
Algae loves warm, wet, sunny places. Your wet curtain tank and pads are perfect for it. Algae blocks the water flow and reduces cooling.
How to control algae:
- Cover the water tank. Use a dark colored tarp or plastic sheet. Sunlight grows algae. Cover blocks light.
- Use algaecide. Buy from a pool supply or farm store. Add 10‑20ml per 100 liters of water monthly. Do not overdo – too much can irritate animals.
- Keep water moving. Stagnant water grows algae faster. Run the pump for a few minutes even when fans are off.
- Clean regularly. Algae builds up slowly. Weekly flushing removes it before it becomes thick.
Water Quality – Use the Right Source
Vietnam has many water sources: river, well, tap, rainwater. Some are hard (high calcium). Some are soft. Hard water leaves white scale on pads and clogged holes.
What to do:
- If your water is hard, install a simple water softener or use a sediment filter.
- If you use river water, filter it through a fine mesh (100 micron) before the tank. River water contains sand, leaves, and small creatures that clog pads.
- If you use tap water, check the pH. Very acidic or alkaline water can damage pads.
Pad Cleaning – Do It Right
Do not use high pressure water directly on the pads. It can break the cellulose fibers. Use a garden hose with a gentle spray. For stubborn dirt, soak the pad in a mild detergent solution (like dish soap) for 30 minutes, then rinse.
Signs pads need replacement:
- Visible holes or tears.
- Hard, crusty surface from mineral scale.
- Collapsed sections where the pad has sagged.
- Cooling drop more than 20% lower than when new.
A Real Example from a Farm in Tien Giang
A pig farmer had a wet curtain system. After 18 months, cooling dropped from 7°C to 3°C. I visited. The water tank was open to sunlight. Green algae filled the tank and clogged the pump intake. The pads had a thin layer of scale.
We cleaned the tank, added a cover, flushed the pads, and replaced the pump intake screen. Two days later, cooling was back to 6°C. The farmer now covers his tank and adds algaecide monthly. His system has run well for two more years.
Troubleshooting Common Problems
| Problem | Likely cause | Fix |
|---|---|---|
| Pads dry in some areas | Clogged water distribution holes | Clean holes with a toothpick or small wire |
| Water dripping outside the barn | Uneven pad or poor seal | Adjust pad position or add sealant |
| Not enough cooling | Pads dirty, pump not working, or humidity too high | Clean pads, check pump, accept lower cooling on rainy days |
| Bad smell from water | Stagnant water, dead algae | Drain tank, clean, add algaecide |
| Pump runs but no water flow | Pump intake blocked or impeller damaged | Clean intake, replace pump if needed |
Spare Parts to Keep on Hand
- One extra water pump (buy locally, same model).
- One set of spare pads (order from your supplier).
- Extra distribution pipe and nozzles.
- Algaecide (enough for 3‑6 months).
Conclusion
Wet curtain cooling drops barn temperature by 5‑8°C in Vietnam, runs on very low electricity, and needs only simple weekly cleaning. It saves your animals and your money.
