A renewable energy system is disclosed for generating electricity that is self-sustaining. In accordance with an important aspect of the present invention, the system takes advantage of the stack effect to create a natural updraft in at least one vertical air column based on the temperature differences of the air in the vertical air column and the temperature of the ambient air adjacent the exhaust port of the vertical column. A wind generator is located in fluid communication with the vertical air column. Once the updraft is created, the blades of the wind generator rotate which causes electricity to be generated.