What is a Solar Chimney?

A solar chimney is a passive climate control feature on a structure that provides ventilation by generating an updraft to pull air through the building. The basic design can be seen in homes in desert regions of the world, including on very old structures, and it is also suitable for other climates. In addition to the basic solar chimney design, it is also possible to use a modification known as a solar updraft tower to generate electricity by turning turbines with the updraft.

The basic design consists of a chimney extending above the height of the building, with paint and glazing to encourage it to attract heat. As the chimney heats, it creates an updraft, pulling air up from the structure below. This ventilates the structure, promoting the even circulation of air and providing some relief to people inside. The solar chimney can often keep interior temperatures stable and comfortable even in very hot weather, and can also be a useful tool for ventilating particularly smelly areas like bathrooms and kitchens.

In the case of a solar updraft tower, the design remains similar, but the chimney includes turbines inside. As air rushes up the chimney to the outside, it turns the turbines, and they generate electricity. In the case of a tower designed specifically to make electricity, an array of solar collectors below can provide a steady source of warm air to rotate the turbines as it rises through the tower. This modification on the solar chimney is an active solar design, acting to convert the sun's energy into electricity.

Natural ventilation is a pressing concern in any climate, and in hot places it can be a particular issue. The solar chimney design is ancient, as numerous examples at archeological sites can attest, and is very easy to integrate into new construction or add to an existing home. People may combine it with other passive climate control measures like thick insulation to keep the air in a home at a stable temperature.

In climates with cold weather, the solar chimney can still be a useful tool. During the summer months it will cool a home, and in the winter, people can close the flues to prevent the escape of air, or open them partially to ventilate while still retaining warm air inside. Solar chimneys can also be helpful for controlling humidity, as the interior of a structure will naturally become drier with the ventilation and can eliminate the unpleasant feeling of heavy, humid air. This will limit mold and mildew and keep the interior air cleaner.