With its sensitive sensor system, the BC25 therefore not only determines common climate parameters such as the air temperature, relative humidity, dew point and wet-bulb temperature, but also the 'heat index' (HI) and the 'apparent temperature' (WBGT index). Both the heat index and the so-called wet-bulb globe temperature provide information on the apparent temperature based on the measured air temperature and in particular the relative humidity and other parameters such as the heat radiation.

Due to the alarm functions of the BC25 for heat index and apparent temperature, thermal damage can be avoided from the start and the limits of stress resistance at high temperatures can be set. The large and easily readable LCD display as well as the functions for automatic switch-off, minimum and maximum value, AVG and HOLD complete the range of features of this innovative measuring device.

The international standard for the climate influence on the human body: wet-bulb globe temperature index (WBGT index)

The wet-bulb globe temperature index is a climate index developed by the US army as early as in the 1950s. It serves to specify the effects of the current climate on the human body.

Unlike the heat index, the WBGT does not only incorporate the air temperature (dry-bulb temperature) and humidity level, but also the wind speed, the wet-bulb and radiation temperature (globe temperature) for assessing the outdoor thermal stress.

The wet-bulb temperature (or theoretical limit of cooling) is the lowest temperature that can be reached through direct evaporative cooling only. It is determined by wrapping a cotton cloth soaked with distilled water around the measuring tip or mercury bulb of a thermometer and then exposing it to the environment. The cooling effect achieved by the evaporated water can thus be measured and simulated for the perspiring human body under these conditions.

The radiation temperature, which is also taken into consideration, is measured inside a thin-walled matt black globe reacting to the infrared heat radiation emitted by the sun. Therefore, the WBGT index is another indicator for determining the climate effects on the human organism. It is, however, even more informative than the heat index since additional parameters are included in the calculation. Established as an international standard, it is described in ISO 7243 and DIN EN 27243.