Wind Towers For Passive Ventilation Cooling In Hot-arid Regions.

In hot-arid regions if the ambient temperature falls within the limits of the comfort zone during the night, day-time thermal comfort conditions can be maintained by careful use of the night-time ventilation. Wind towers or catchers have been in use for centuries have proven to be effective in trapping outside air. Primarily, this study investigates the traditional types of wind towers for the purpose of natural ventilation cooling. Using The University of Michigan Wind Tunnel several experiments testing certain varieties of physical models of wind towers were completed. The tunnel was improved to produce a wind flow with characteristics similar to that of the atmospheric boundary layer wind of both urban and suburban areas. Four traditional types of catching devices were experimentally investigated. These four types are found widely in hot-arid countries and each of them represents a unique concept of wind catching. The effects of both the nearby surroundings and the internal design of the dwelling unit on the performance of wind towers were explored for particular configurations. In addition, the effect of the geometric shapes of the wind towers regarding their performance was thoroughly investigated using abstract models. The proper orientation of wind towers for receiving the maximum available ventilation for a typical hot-arid city, Riyadh, Saudi Arabia, was accomplished by the analysis of its climatic data. The research produced information that has implications on the design of the wind tower system. Several graphs were obtained that can help in selecting the appropriate type of catching device for any wind condition and in estimating the anticipated ventilation flow through the catching devices for any orientation. Charts and regression models were also obtained in order to modify the estimates of ventilation flow due to tower height with respect to nearby surroundings. Charts and graphs were produced to show the differences and similarities between various geometric forms of wind towers, and the effect of both orientation and length-width ratio on the performance of the wind catchers. In addition, a new method, the wind impact factor (WIF) of analyzing climatic data for the appropriate orientation with respect to natural ventilation was developed. (Abstract shortened with permission of author.)Arch.Dr.ArchitectureCommunication and the ArtsUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/127991/2/8712052.pd