Understanding the relationship between dry bulb temperature, wet bulb temperature, relative humidity, and dew point temperature is essential in all facets of air conditioning. These psychrometric processes play an especially important role in building and materials integrity, occupant health and comfort, and overall indoor air quality.
To evaluate relative humidity, wet bulb temperature, and dew point, HVAC technicians traditionally used a sling psychrometer and psychrometric chart. Nowadays they use "humidity" meters that are accurate, more convenient, and usable in confined locations unsuitable for sling psychrometers.
From dry bulb temperature and relative humidity measurements, temperature humidity meters such as the Fluke 971 can calculate wet bulb temperature and dew point temperature, psychrometric points that are essential for HVAC evaluations and diagnostics.
Many states have adopted ANSI/ ASHRAE Standards 552004 on humidity and 622004 on IAQ into their building codes. Since both standards have been newly updated, inspectors and contractors may need to update practices to meet new requirements.
For standards details and measurement techniques applying to relative comfort, humidity levels, fungus, and condensation, as well as for a description of related terms and resources, please download the complete article »