The utilization of energy from renewable sources, Such as wind, is becoming increasingly attractive and is being widely used for the substitution of oil-produced energy, and eventually to minimize atmospheric degradation. Literature shows that commercial/residential buildings in Saudi Arabia consume an estimated 10-40% of the total electric energy generated. In the present study, hourly mean wind-speed data for the period 1986-1997 recorded at the solar radiation and meteorological monitoring station, Dhahran (26degrees 32' N, 50degrees 13' E), Saudi Arabia, have been analyzed to investigate/examine the role of hybrid (wind + diesel) energy conversion systems in meeting the load requirements of a typical commercial building (with annual electrical energy demand of 620,000 kWh). The monthly average wind speeds for Dhahran range from 4.1 to 6.4 m/s. The hybrid systems considered in the present analysis consist of different combinations of the commercial 10 kW wind energy conversion systems (WECS), supplemented with battery storage unit and diesel back-up. The study shows that with thirty 10 kW WECS and 3 days of battery storage, the diesel back-up system has to provide 19% of the load demand. However, in the absence of battery storage, about 40% of the load needs to be provided by the diesel system. (C) 2003 Elsevier Ltd. All rights reserved.