The aim of this study was to analyze savings in the annual cooling energy need for the FAMENA building using hybrid cooling which includes the combination of passive and mechanical cooling. It was assumed that the passive cooling is achieved solely using cross ventilation due to wind forces. TRNSYS software was used for the calculation of the annual cooling energy needs, while software CoolVent was used for passive cooling simulations. The study includes the description of the programs that were used, as well as the description of mathematical models of a multi-zone building and cross-ventilation. Taking into account the occupancy schedule of the building (every day from 8 AM to 6 PM, excluding weekends and annual vacation leave) and the set temperature of 26°C it was calculated that the annual cooling energy need without the use of passive cooling amounts to 68,386 kWh (14.3 kWh/m2). By using the results of passive cooling simulations the upper limit of outdoor temperature for each month was determined under the condition that the indoor temperature is lower than 26°C and thereby meets the thermal comfort requirements. The passive cooling potential was estimated by comparing calculated outdoor temperatures with the typical meteorological year for the city of Zagreb. The results show that passive cooling can meet 20.1% of annual cooling energy needs assuming the optimal operable window area of 14 m2 by floor and façade.