The aim of this paper is to optimize the energy performance of cylindrical cross section evaporative wind towers as passive systems for thermal conditioning of urban spaces. Two theoretical models, a thermal model and a fluid model, have been developed to characterize the evaporative system and the tower design respectively. The thermal model evaluates the tower operation when the fan and the nozzles are working, giving as result the difference between the outlet temperature and inlet temperature. This model has been used to analyze the thermal response of the system to fluctuations in design parameters (water flow, air flow and absorption coefficient of the plastic). To that effect, three one-parametric and one multi-parametric optimization have been done. The fluid model describes the tower operation when the fan and the nozzles are not working, giving as result the wind behavior through the tower. Additional configurations of the wind tower have been evaluated: changing the number of the wind catcher openings, varying the height of the internal walls of the tower and modifying the geometry of the lower ventilation apertures. (C) 2012 Elsevier Ltd. All rights reserved.