Variations in Estimated WBGT Due to Instrument Differences

Sharp-eyed users of Heat Stress Adviser will notice that the same values, entered into different calculators, give different results.

The reason for this seeming inconsistency is that the inexpensive consumer-grade instruments used to generate data for Heat Stress Adviser vary in their response to environmental conditions. Each of these devices was compared to an industrial-quality logging heat stress monitor. So, Device A might have reported Dry Bulb = 92°F with Wet Bulb 77°F, at the same time that Device B was reporting Dry Bulb = 98°F with Wet Bulb 78°F. (Such large differences were not observed when various industrial-quality devices were compared.)

As a result, each of the instruments used was given its own mathematical model.

When comparable data for each instrument was entered into the various models, the results were usually within ± 1°F. This level of precision is felt to be very good for inexpensive consumer-grade instruments.