4 Heat Absorbing Materials Common in Solar Chimney Use

rooftop chimney

The solar chimney is just one of many types of alternative power sources being explored in the world right now. Also known as a thermal chimney and solar updraft tower, the solar chimney is now being used by many buildings in order to improve the natural ventilation. Solar chimney works by utilizing convection of air produced by the heat of passive solar energy. This type of chimney looks similar to any traditional chimney. But compared to other chimneys, a solar chimney is a vertical shaft that uses solar energy to improve the ventilation of a house or building.

There are other benefits of using solar chimneys instead of the traditional chimneys. A solar chimney not only improves the ventilation of a building especially during hot days, but it also improves the air quality inside a building; additionally it can minimize the noise coming from outside.


The chimney is basically made of reinforced concrete that can easily absorb heat which can be transformed to usable energy. In fact, the chimney itself acts as a thermal engine. Due to its favorable surface to volume ratio, the chimney acts like a pressure tube with low friction loss.

Solar chimneys made of concrete can be built easily. All you have to do is create a hollow cylinder with large diameter. It is quite simple but it is not particularly slim. In some large cities, such as Toronto and Tokyo, you’ll be able to find tall buildings with solar chimneys.


Solar chimneys can also be made of glass, which is also known to be good heat absorbing material. Glass is extensively used in building the solar collector area of the solar chimney which is usually situated on top of the chimney or sometimes the entire shaft. There are usually three to five vertical shafts needed for the cooling and ventilation process.

Stainless steel

Chimneys made of stainless steel can also absorb heat easily. Moreover, this material is perfect for enhancing the airflow inside a building or house because it is a low friction material. The solar chimney is made of a minimum of three basic stacks, one of which is the round exhaust stack made of stainless steel. The airflow inside the building is improved when the stainless steel chimneys produces “stack ventilation”. This stack effect is necessary for the building; especially during warm days; it facilitates hot air to escape.

Black ceramic gravel

Experts agree that black ceramic gravel is the best material to use as solar collector for a solar chimney. The optimum size of the collector for the solar chimney depends on the amount of ventilation power you would like to produce. Naturally, a collector made from black ceramic gravel absorbs little heat if it is small. Keep in mind that dark materials are good conductors of heat. When the sun’s light strikes a dark object, it is turned to heat power. A solar collector made from black ceramic gravel is also used in conjunction with wind at a sun power plant; great types of alternative energy.