If you’ve ever wondered why evaporative cooling works extremely well in some locations but less effectively in others, the answer is largely related to humidity.

Evaporation needs capacity

An evaporative cooler relies on water changing from liquid to vapor.

That process absorbs heat.

But air can only accept so much additional moisture.

Dry air has greater capacity for evaporation, while humid air has less.

Temperature alone isn’t enough

Two factories may both experience 35°C outdoor temperatures but have very different evaporative-cooling performance if their outdoor humidity levels are different.

The source material gives an example of approximately 35°C outdoor temperature and 56% relative humidity, under which it reports outlet air around 26–28°C for the particular system discussed. That is a source-specific example, not a universal performance guarantee.

What happens to indoor humidity?

Evaporative cooling adds moisture to the air.

For many industrial applications, that may be acceptable.

But applications requiring tightly controlled humidity may need another type of cooling system.

A practical way to think about it

Evaporative cooling is especially attractive when you want:

Fresh air + cooling + ventilation

rather than:

Precisely controlled temperature + humidity

Before selecting an evaporative cooler, evaluate:

• outdoor temperature
• outdoor relative humidity
• required indoor conditions
• ventilation requirements
• process sensitivity to humidity

The climate should be considered before the equipment.