A solar chimney - often referred to as a thermal chimney - is a way to improve the natural ventilation of buildings using the convection of air heated by passive solar energy.

A simple description of a solar chimney is that of a vertical shaft that uses solar energy to enhance the natural ventilation of the stack of floors in a building.

In its simplest form, a solar chimney consists of a chimney painted black. During the day solar energy heats the chimney and the air inside it, creating an upward draft of air in the chimney.

The suction created at the base of the chimney can be used to ventilate and cool the building.

In much of the world it is simpler to take advantage of the prevailing winds of the site, but on calm, hot days this type of chimney can provide ventilation where there would otherwise be none.

There are however a number of solar chimney variations. The basic elements of the design of a solar chimney are:.

Taking advantage of the same operating principle, solar electric generation systems have been proposed with a large greenhouse at the base to heat the air that then rises at high speed through a high chimney where the wind turbines are located. It is also called a cyclonic power plant.

A technology closely related to the solar chimney is the downdraft evaporative cooling tower. In areas with a hot and arid climate, this system can help provide sustainable air conditioning to buildings.

National Renewable Energy Agency (NREL [1]).