The Wet Bulb Globe Temperature Index – WBGT Index – is a perceived temperature, which makes statements about the manageable physical strain depending on temperature, wind speed, humidity and solar radiation.
The WBGT Index was developed in the 1950s by the U.S. Marine Corps and is widely used today, particularly in the United States.
Meaning of the WBGT Index
Calculation of the WBGT Index
The WBGT index is expressed in °C and can be determined according to the following formulas
- Inside and outside buildings and without direct exposure to solar radiation:
WBGT = 0.7 * Tnw + 0.3 * Tg
- outside buildings and with direct exposure to solar radiation:
WBGT = 0.7 * Tnw + 0.2 * Tg + 0.1 * Ta
- Tnw Temperature of a naturally ventilated, humidified thermometer in °C
- Tg Globe temperature in [°C]
- Ta Air temperature in [°C]
Globe temperature and temperature of a naturally ventilated humid thermometer are mixed variables. They are influenced by the climatic variables air temperature, humidity (Tnw only), thermal radiation and air velocity.