Trend Investigation of Thermal Comfort in Different Climates of Iran in Past Decades

Abstract

Regarding climatic diversity in Iran and the dependence of many outdoor activities (occupational, recreational, tourism attraction, etc.) on climatic conditions, this study conducted aiming to evaluate thermal comfort fluctuations in Iran. Thermal comfort fluctuations in different climates of Iran were investigated between 1985 and 2014 using recorded meteorological data in 40 synoptic stations. The Mann-Kendall test and Sen’s Slope were used to analyse the changing trends of the Humidex and to determine the actual slope of a trend over time, respectively. In overall, the southern areas of Iran have the longest period with unfavourable and extremely unfavourable climatic conditions in this study. Conversely, in the northern half of Iran, especially in North West areas, the appropriate summer season provides the best climatic conditions for outdoor activities.

Trend analysis of Humidex as a heat discomfort index using Mann-Kendall and Sen’s slope estimator statistical tests

“…The HD index was first expanded in Europe and the United States where it was used by meteorological organizations to determine the likelihood of heat stress and thermal comfort conditions in a particular area and was reported to the public (27). The interpretation of the range of this index from a value of 20 to above 54 is expressed in Table 1.…”

“…The first principle, based on the equilibrium equation of the human body, states that the thermal equilibrium of the human body when exposed to heat is in the range of 27 to 30°C (if naked and presiding in static air). The second principle states that at humidity higher than 75%, the human body is incapable of enduring temperatures exceeding 32°C (27). Based on the abovementioned issue, it can be stated that HD, a commonly used experimental index based on temperature and relative humidity, does not take into consideration many other factors influencing heat stress such as clothing resistance, rate of metabolism, and air velocity (28).…”