An analysis of the influence of air temperature and humidity on outdoor thermal comfort in Belgrade (Serbia) using a simple heat index

Abstract

The main objective of this paper is to study the outdoor thermal comfort of the central urban zone of Belgrade during summer season in order to examine how different bioclimatic conditions affect human body. For this purposes Humidex, a simple heat index was applied. The research involved analyzing different Humidex values, the so-called "sub-indices" calculated based on hourly (7:00 and 14:00), mean daily and maximum values of meteorological parameters (air temperature and humidity) that were recorded at the meteorological station Belgrade - Vracar.), for the period 1999-2018. Outdoor thermal comfort in Belgrade is generally more adverse in July and August, resulting in most days belonging to the categories of "some discomfort" (30-39) and "great discomfort" (40-44), with periodic recording of the most severe categories of heat stress, as a category "very dangerous"(Humidex>55). Category of "very dangerous" heat stress shows linear increase during July, with positive trend of 0.03 days/10 years. The findings also show that from 1999 to 2018, mean index value gradually rose and values of sub-indices Humidex(14h) and Humidex(Tmax) have exceeded thresholds 40 for great discomfort and 45 for dangerous heat stress more often then in the previous decades.