Charting Psychrometric
Experts use a Psychrometric Chart to graphically understand the relationship between temperature and humidity. This chart is also a valuable resource for building maintenance and operations personnel because it provides a visual representation of the relationship of moist air and temperature.

Apollo BBC has developed a version of the Psychrometric Chart that includes the most useful information to operators. For a copy of our chart, please refer to Psychrometric Chart.

 

Humidity, or water vapor, can cause indoor spaces to feel uncomfortable--even at a reasonable temperature. Humidity can be the source of water dripping from supply air diffusers, collecting around water pipes, or running down the inside of windows. Humidity can also be the cause of an unseen problem--sweat forming behind walls.

Psychrometrics is the science of the interaction of dry air and water vapor, and the processes that change the temperature or water vapor content of this mixture. The behavior of humidity is difficult to understand without a grasp on a few key concepts and delineations: relative humidity, specific humidity, wet bulb temperature, and dew point temperature.

Water, whether vapor or liquid, can create a host of problems for occupant comfort, building HVAC systems performance, and building enclosure performance.

This article is meant to further explain the technical concepts of humidity and its effects on the indoor environment and the building enclosure.

Psychrometrics Page 1 - Introduction Page 2 - Indoor Comfort Page 3 - HVAC Systems Page 4 - Building Enclosures Page 5 - Definition of Terms