Home Distress Index/Heat Index/Thermal Comfort Index

Distress Index/ Heat Index/ Thermal Comfort Index


The heat index shows "how warm we really feel" by combining the current temperature with the relative humidity. Is that the degree of discomfort/distress of human due to influences of thermal and humidity conditions.

At elevated temperature conditions the human body regulates its temperature through sweating. So, it removes heat by evaporation of sweat. Under conditions of increased humidity, evaporation of sweat is limited, so we feel the temperature higher than it really is.

The following equation is used for the calculation of heat index (° C):

DI = Tα – 0,55 (1 – 0,01 RH) (Tα – 14,5) 


Assessment of discomfort/distress based on the discomfort/distress index values (Giles et al., 1990)


DI (oC)

Distress Type


No distress

21 < DI < 24

< 50% of population feels distress

24 ≤ DI <27

> 50% of population feels distress

27DI <29

The major part of population feels distress

29DI <32

Everyone feels distress

   DI≥ 32

Increased awareness in hospitals