Why is Dew Point Important for Managing my Environmental Conditions?

1) In practice, the dew point is often the limiting factor of your mechanical system.

A building's mechanical system is designed to modify the outdoor air in order to achieve the appropriate conditions of the indoor air. This task involves adjusting both the temperature and the moisture content of the outside air. In general, it is easier (less energy consuming and more straight forward from a control point of view) for the mechanical system to cool or heat the air than it is to add or remove moisture. In other words, it is easier for the mechanical system to alter the temperature than it is to regulate the absolute moisture content of the air (its dew point).



Therefore, in practice, the goal for improving the preservation quality of your environment can be defined by controlling the dew point. In the winter, you must raise the dew point – to avoid excessive dryness – and, in the summer, you need to lower the dew point – to avoid excessive dampness.


#2) Dew point determines which combinations of temperature and RH will be possible in your environment.

Because Temperature, RH, and Dew Point are interrelated, the dew point that your mechanical system can achieve will determine which combinations of temperature and RH are possible in your environment.

We have come to realize that, in many cases, the preservation quality of the environment depends more on achieving low summertime dew points than any other single factor.


#3) The dew point can reveal a lot of about your mechanical systems.

For larger institutions with mechanical systems that serve several rooms, floors, or even buildings, graphing the dew points (both outdoor and indoor dew points) can reveal valuable information about the performance and design of your mechanical systems.

  1. Overlaying the graphs of indoor and outdoor dew points allows you to evaluate how well your mechanical system is performing.

    In the image below, the yellow line represents the graph of the indoor dew point for the location named “Conservation.” The green line represents the outdoor dew point for the outdoor climate where this institution is located.

  2. Overlaying the graphs of the indoor dew points for several locations, you can see which locations have air from the same air-handling unit (AHU) in the mechanical system.