air movement, thermal sensation and comfort in black tent case study: region of ilam

the functions of shelters are basically the same everywhere: to avoid extreme weather and to provide shelter for a comfortable living and working environment; but the designs and processes for those in different climates are significantly different. to live in the tropical area, olgyay stated two major problems the habitants have to be prepared for: the avoidance of excessive solar radiation and the evaporation of moisture by breezes. one of the regional solutions is, for example, to allow free air movement into the space of the question. this study will try to find the effect of air-movement on black tent design according to human comfort and based on theoretical research and field study, aiming at clarifying the significance of the issue itself and the application which can be employed in the design of built environments. many nomadic families, for example in ilam, pack up their homes and move towards the sun in autumn and away from it in summer. not only are they physically moved from the warmer, lower winter quarters up to cooler, higher pastures in the summer. an example of an adaptable building form is the nomadic tent. in winter the tent is closed right down to keep out the wind and rain but, as spring turns to summer, its cloth opens up, like wings, to form little more than a sun shade for the people inside. by making the envelope of the tent so adaptable, the range of climates in which its occupants can be comfortable, are considerably extended. the tent cloth is raised to let in the warm breezes and in midsummer the tent cloth becomes a sun shade and as a pump to pull the fresh air into space. this paper, however, gives an account of an investigation of the performance of this traditional space in the city of ilam, according to its ability to creating comfortable condition by letting fresh air into tent. the city of ilam is located in the west of iran, and it lies at 1319 meters above sea level on latitude 33? 38? n and 46? 26? e longitude. ilam is in the zagros region which is one of the four major parts of iran. in this city the temperature difference between summer and winter and also between day and night is great, so that is creates an environmental conflict. two months in the winter and five months in the year are periods featuring rather harsh conditions as cold and hot respectively. during the critical summer months many people moved from their place to another for achieving thermal comfort. because of this, they are using tent as a home. it seems that the features of traditional form of black tents reflect the delight of regional and visual/aesthetic values, mainly related to culture and climate. inside the tent, cross ventilation is considered as the main feature to achieving comfort, giving fresh air across the body to reduce perspiration. the movement of air is more noticeable when solar radiation is under consideration.