Plastic Less Efficient Than Paper Evaporative Cooler Pads

The cooling effect of plastic evaporative cooling sheets is not as good as that of paper cooling sheets. This is the conclusion from a thorough comparison of both systems under different environmental conditions. It offers lower cooling, higher initial cost, and/or the necessity of a large number of interior fogging system nozzles to improve cooling.


It might not look like it but significant engineering went into designing and building the modern paper evaporative cooler pads. The pad flute sizes must be optimized for cooling the incoming air. They also need to be small enough to allow airflow to flow freely, which will increase the tunnel fan’s performance. It is a complex balance. It’s a delicate balance. You must design the angles of the flutes so that the water flows through the pad in a way that keeps the surfaces and flutes clean. This is to maximize the tunnel fan’s wind speed. The hardest part about designing a paper pad of quality is engineering the paper.

Evaporative cooling pad papers are infused with resins. After being cured, it becomes soft and porous enough so that water can easily wick throughout the entire pad. To maximize cooling from a pad, it is important to have a wicking mechanism. It prevents dry spots from developing. Second, a paper pad’s wicking properties allow it to absorb large amounts of water.

Same Design Different Cooling Results

While the design of plastic evaporative cooling cushions is similar to traditional papers, there are many differences. One difference between the two is that plastic pads don’t have alternating channels or flutes. They instead use alternating curved, or “U”, shaped flutes. The flutes have tiny holes which allow for more surface area and water flow. This is a critical challenge for any plastic evaporative cooling pad.

Water doesn’t need to be delivered directly onto every square inch of a traditional paper pad. This is because of the paper’s wicking ability. A single stream of water can wet only a few inches on each side of a pad. A plastic pad cannot do the same. The pad must have a significantly higher water flow than a paper pad to keep it wet.

Increased Humidity

It is important not to forget that “evaporative” cooling doesn’t always equal “bird cooling.” If it does, then we use evaporative chilling to lower our house temperatures in hot weather. This allows heat to transfer more efficiently from the birds to the atmosphere (sensible warmth loss). The downside to this cooling is the increased humidity.

The relative humidity is decreasing, even though the air temperature is higher. This decreases the bird’s ability and capacity to cool itself via the evaporation from its own body. Although we are reducing the house’s temperature by using evaporative air cooling, we are increasing humidity which adversely affects the bird’s primary means for cooling itself.

The plastic pad’s higher house temperatures come with lower relative humidity. This makes a bird lose heat faster through the evaporation from its respiratory system. Wind speed is less effective at removing heat because it is closer in temperature to birds, but the relative humidity is higher, so the bird is losing more heat via evaporation. Is the paper pad better for birds? It is how warm a house is during hot summer days that will determine the final answer.