What is eWBGT?
eWBGT is an estimation of Wet Bulb Globe Temperature that can be automatically gathered by SlateSafety BEACON V2s. eWBGT can be viewed, analyzed, and alerted on using SlateSafety's software.
What is Wet Bulb Globe Temperature?
Before we can explain eWBGT, first we must review Wet Bulb Globe Temperature (WBGT). Wet Bulb Globe Temperature is a measure of the heat stress in direct sunlight, which takes into account: temperature, humidity, wind speed, sun angle and cloud cover (solar radiation). It integrates data from three types of thermometers to assess how heat affects the human body. These include:
- Wet Bulb Thermometer: This device is covered with a wet cloth, mimicking the human body's sweat cooling mechanism. The cooling effect on the thermometer as the water evaporates provides a measure of humidity's impact.
- Black Globe Thermometer: Used for assessing solar radiation, it simulates the warming effect of the sun on the human body. Wind helps to cool the globe, indicating the cooling effect of air movement.
- Dry Bulb Thermometer: It measures ambient air temperature in the shade, reflecting the general outdoor temperature.
The WBGT index is thus a comprehensive gauge of environmental factors influencing human heat stress.
Differences between WBGT and eWBGT
| WBGT (Wet Bulb Globe Temperature) | eWBGT (Estimated Wet Bulb Globe Temperature) |
| Measured via WBGT sensors and combined | Estimated via SlateSafety BEACON V2s. eWBGT is based on work done by Thomas Bernard et al (1999) for estimating WBGT using Air Temperature and Relative Humidity. |
| Accurate indoors and outdoors | The estimation has been proven accurate for indoor and shaded outdoor environments |
How is eWBGT calculated?
SlateSafety BEACON V2s measure Air Temperature and Humidity in real time. Using the estimation calculation provided by Thomas Bernard et al (1999), these two measurements can be used to estimate Wet Bulb Globe Temperature. The table below displays the mappings of air temperature and humidity measurements to eWBGT.
Why use estimated WBGT instead of actual WBGT?
- Wet Bulb Globe Thermometers can be very expensive. SlateSafety BEACON V2s are much more affordable.
- BEACON V2s can be installed in multiple places throughout a facility to provide real-time visibility into the environmental conditions using SlateSafety's cloud-based software.
- eWBGT data is recorded in the cloud and a full history can be viewed through SlateSafety's software.
- Alert thresholds can be set, allowing you to receive notifications whenever eWBGT crosses a threshold.
