Understanding Relative Humidity and Mist Pre-Cooling


Quick Facts:

  • It is true that the potential temperature drop from mist cooling is affected by humidity
  • But it is important to know that humidity goes down as the temperature goes up
  • Most people over estimate their actual humidity level during the heat of the day
  • SMARTMIST™ mist pre-cooling works well in all climates


The results are so reliable that we offer the industry's first:

Since the cooling capacity for the SMARTMIST™ 100° Pure Evaporative Air Pre-Cooling System is determined in a large part by the actual humidity during operation, it is important that you understand how humidity works and changes with the rise and fall in the daily temperature.

When checking the below “Potential Temperature Drop” chart, people living in high humidity climates may not realize how much of an actual temperature drop they can expect while using a AC mist pre-cooling system. What they do not know is that, even in a high humidity climate, during the heat of the day (when pre-cooling is needed most) the actual humidity level can be 30° to 50° lower then what is being reported for that day. This is because the humidity level is “Relative” to other conditions, mainly the dew point. So, the farther above the dew point temperature the temperature rises, the lower the humidity becomes.

Below is an example of a random day in Baton Rouge, LA (a very humid climate). You will notice that the highest reported humidity (above 90°) is only during the night and early morning, but by mid morning the humidity level starts to drop and continues to drop in relation to the rising temperature, until it reaches a low of 36°. Then at about 5:00 PM, it starts to increase as the temperature starts to decrease again.

This means that for pre-cooling Dry Cooling Towers or Turbine intake air, you would realize a significant temperature drop of 15 to 25 degrees during the main operating hours for this day even in Baton Rouge, LA

You can check out your area?s Humidity / Temperature history at: www.wunderground.com 

You can check out your area;€™s Humidity / Temperature history at: www.wunderground.com


Note: SMARTMIST™s Evaporative Air & Direct Heat Exchange Pre-Cooling for AC and Refrigeration Pre-Cooling is not affected as much by humidity and can maintain maximum results at any humidity level.




The SMARTMIST systems are a proven technology that will boost the efficiency of most air cooled systems thus significantly increasing their performance and/or lowering energy use and costs.;  After auditing your equipment and needs, we will provide you with a minimum performance contract that will guarantee a minimum average performance increase and/or energy savings.

If your minimum performance increase and/or energy savings is not met during the first 60 days of operation, we will promptly remove our equipment and refund 100° of your money including equipment and labor upon your request.*

*Request must be made within 90 days of initial installation.;  See contract for more details.

Evaporative Air & Direct Heat Exchange Pre-Cooling

This is where we use lower pressure (180 PSI) pumps, larger atomizing nozzles and automated controls to achieve a combination of air cooling and direct Heat Exchange water cooling.;  Meaning we cool the surrounding air of the heat exchanger, as well as get the coils slightly damp (with non-scaling, treated water). This gives us the largest efficiency boost for Air Conditioning and Refrigeration Condensers.