Solar Chimneys

Air conditioning and mechanical ventilation have been for decades the standard method of environmental control in many building types, especially offices, in developed countries. Pollution and reallocating energy supplies have led to a new environmental approach in the building design.

A solar chimney (or a thermal chimney) is a way of improving the natural ventilation of building by using air heated by passive solar energy. Passive solar technologies are means of using sunlight for useful energy without using any active mechanical systems. Such technologies convert sunlight into heat or cause air movement with little use of other energy sources. Simply said, solar chimney is a vertical shaft which utilizes solar energy to enhance the natural ventilation through a building.

In its simplest form, the solar chimney consists of a black-painted chimney. During the day, solar energy heats the chimney and the air within it, creating an updraft of air. The suction created at the chimney’s base can be used to ventilate and cool the building bellow.

Actually, a solar chimney can serve many purposes. Direct gain warms air inside it causing it to rise out the top and drawing air in from the bottom. Secondly, natural ventilation can be created by providing vents in the upper level of a building to allow warm air to rise by convention and escape outside. At the same time, cooler air can be drawn in through vents at the lower level. Now, this natural ventilation process can be augmented by the solar chimney.

To further maximize to cooling effect, the incoming air may be led through underground ducts before it is allowed to enter the building.

There are many benefits of using a solar chimney, such as improved ventilation rated on still, hot days; reduced reliance on wind and wind driven ventilation; improved control of air flow through a building; greater choice of air intake; improved air quality in urban areas; increased night time ventilation rates; allow ventilation of narrow, small spaces with minimal exposure to external elements.