Poultry Cooling Pads: How They Work, What They Do, and Where They Stop

Cooling pads are standard equipment in Indonesian close house barns. Most producers fit them because that is the standard, without fully understanding what the equipment can and cannot do.

This article covers the mechanism, what drives performance, and where the limits sit.

How a cooling pad works

A cooling pad is porous media — usually corrugated cellulose paper treated with resin — mounted at the house inlet and kept continuously wet. Exhaust fans at the opposite end create negative pressure, pulling outside air through the wet pad.

As air passes through the wet media, some water evaporates. Evaporation absorbs heat from the air itself — roughly 680 Wh per litre evaporated. The air entering the house is therefore cooler than the air outside.

This is adiabatic cooling: no cooling energy is added, heat merely changes form from sensible heat (what a thermometer reads) into latent heat (stored in water vapour). Which is why air leaving the pad is both cooler and more humid.

What determines how cool it gets

The temperature drop a pad achieves is not fixed. What governs it is the humidity of the outside air.

The drier the incoming air, the more water can evaporate, and the larger the drop. In dry air, drops of 10 °C or more are achievable. In already-humid air, there is little room for evaporation and the drop is far smaller.

That is unwelcome news for Indonesia: high humidity is the normal condition, so pads here operate well below their theoretical potential. The same pad delivers very different results in a dry climate.

Other factors:

• Pad thickness. Thicker media gives longer air-water contact and higher efficiency — at the cost of greater airflow resistance.
• Air velocity through the pad. Too fast and contact time is insufficient. Too slow and the air volume will not serve the house.
• Water distribution. Dry patches cool nothing — air passes straight through with no evaporation.

The limits worth understanding

The gradient along the house

This is the decisive limitation. A cooling pad conditions air at one point — the inlet. After entering, that air travels the length of the house picking up heat from the birds, the floor and roof radiation.

The result is that the exhaust end always runs warmer than the inlet end. In a long house the difference can be several degrees. Birds in the hottest zone experience conditions quite different from birds near the inlet — same flock, same house.

No pad setting eliminates this gradient. It is a consequence of geometry, not a configuration error.

The humidity it adds

Air leaving a cooling pad is more humid. In a house where humidity is already high, that addition reduces the birds’ ability to shed heat by panting.

There is a point where further cooling is counterproductive: the air is genuinely cooler, but the birds have lost their main heat-loss pathway. Pad operation should therefore be governed by humidity sensors rather than run continuously.

Maintenance is not optional

A poorly maintained pad stops working, and often creates new problems:

• Mineral scale from hard water blocks the media pores, cutting evaporation and adding airflow resistance.
• Algae and moss grow on media that is damp and lit, introducing a biological risk into the incoming air.
• Uneven water distribution leaves parts of the pad dry; air passes through uncooled.
• Damaged media creates gaps — and air always takes the path of least resistance, which is the gap.

Water quality drives pad life. High mineral content accelerates blockage significantly.

Pads and misting: not an either-or

The question usually gets framed as “cooling pad or misting?” — but the two address different parts of the problem.

	Cooling pad	High-pressure misting
Where cooling happens	At the inlet	Along the house
Addresses the gradient	No	Yes
Principle	Evaporation	Evaporation
Droplet size	No droplets — evaporation in media	Under 10 microns in air
Wet litter risk	Low	Low at 70 bar, high with low-pressure fogging
Main maintenance	Media cleaning, water quality	Nozzle cleaning, water filtration

Pads lower the temperature of incoming air. High-pressure misting adds cooling at points along the house, including the hot zone the pad’s effect never reaches. In long houses the two are often used together.

What should not be done is addressing the gradient with low-pressure fogging. Droplets of 50 microns and up do not evaporate before landing — litter cakes, ammonia rises, and the resulting health problems cost more than the heat problem they solved.

In short

A cooling pad is the right technology for a clearly defined job: cooling air before it enters the house. It cannot remove the temperature gradient along the house, its performance is capped by outside humidity, and without routine maintenance it stops working quietly.

If your exhaust end runs consistently hot while the pad is functioning normally, the pad is not the problem — that is geometry, and the fix is misting along the length of the house. Send house dimensions and a zone layout over WhatsApp and we will size it.