The influence of wind on outdoor thermal comfort in the city of Beirut: A theoretical and field study

Abstract

This article studies the outdoor comfort in the city of Beirut to improve the quality of open spaces and better explain the people's tolerance and acceptance of outdoor environmental conditions. Field experiments were conducted to develop statistical correlations for thermal sensation and thermal comfort of people in the outdoors to environmental parameters. A transient bioheat model was developed to study the effect of wind speed and frequency in the physiological responses of the human body and its effect on the overall body thermal sensation and comfort state. The model was experimentally validated and simulated for three different wind frequencies of 0.15, 0.25, and 0.35 Hz, representing a range of wind frequencies encountered during an average summer day. For each of these wind frequencies, simulations were performed for two air velocity ranges: V1 = 0.5 m/s to 2.8 m/s (1.64 ft/s to 9.18 ft/s) and V2 = 0.5 m/s to 1.8 m/s (1.64 ft/s to 5.9 ft/s) at air temperatures of 30°C and 34°C (86°F and 93.2°F) and relative humidity of 40% and 70%. The numerical results showed that for velocity range V1, the overall comfort improved from –1.15 to –0.82 with the increase of wind frequency, while at velocity range V2, comfort improved from –1.27 to –0.99 with wind frequency for the same air temperature and relative humidity. It is concluded that the positive effect of wind frequency and velocity amplitude in making people more tolerant of outdoor conditions decreases with the increase in air temperature and relative humidity.

Acknowledgment

The financial support of the Lebanese National Counsel for Research is highly acknowledged.

K. Ghali, PhD, Associate Member ASHRAE, is Associate Professor. N. Ghaddar, PhD, Member ASHRAE, is Associate Provost and Endowed Qatar Chair in Energy Studies Professor. M. Bizri, is Graduate Student.