Thermal conditioning for urban outdoor spaces through the use of evaporative wind towers

The aim of this paper is to study the thermal comfort levels achieved in open spaces by means of evaporative wind towers. These systems have been installed in an urban area characterized by its hot and dry summer climate. Conventional wind tower designs for enclosed and semi-enclosed spaces have been adapted for this new installation. These systems are usually composed of a few number of wind towers, this one however is composed by a group of sixteen, increasing the total dimensions of the installation. To integrate this construction into the urban public area, it was built in a circular arrangement, creating an activity and meeting point for pedestrians. This passive system was monitored during the summer of 2008. Measurements of temperature, solar radiation, humidity and wind speed were analyzed. During the analyzed period, the average cooling efficiency of the system varied from 38% at the exit of the tower, to 32% at 1 m high. At this last position, the average exceeds the wet bulb temperature up to 8 °C with an increase of moisture around 27%. The shading effect produced by the global installation itself has been modeled theoretically to evaluate the incident solar radiation at the pedestrian area. Two indices have been applied to predict the perception of heat and cold in the south pedestrian zone: Heat index and TS index. In this position, both variables approached the thermal sensation to the comfort levels by the use of these passive strategies when ambient conditions are hot and dry.